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  • 651.
    Sandlund, Jonas
    et al.
    University of Gävle, Centre for Musculoskeletal Research.
    Röijezon, Ulrik
    University of Gävle, Centre for Musculoskeletal Research.
    Björklund, Martin
    University of Gävle, Centre for Musculoskeletal Research.
    Djupsjöbacka, Mats
    University of Gävle, Centre for Musculoskeletal Research.
    Acuity of goal-directed reaching movements to visible targets in chronic neck disorders2007In: Sixth International Scientific Conference on Prevention of Work-Related Musculoskeletal Disorders, 2007, p. 10-Conference paper (Other academic)
  • 652.
    Sandlund, Jonas
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research. Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
    Srinivasan, Divya
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Heiden, Marina
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Differences in motor variability among individuals performing a standardized short-cycle manual task2017In: Human Movement Science, ISSN 0167-9457, E-ISSN 1872-7646, Vol. 51, p. 17-26Article in journal (Refereed)
    Abstract [en]

    Motor variability (MV) has been suggested to be a determinant of the risk for developing musculoskeletal disorders in repetitive work. In this study we examined whether individuals consistently differed in the extent of motor variability when performing a standardized short-cycle manual task. On three separate days, arm kinematics was recorded in 14 healthy subjects performing a pipetting task, transferring liquid from a pick-up tube to eight target tubes with a cycle time of 2.8 s. Cycle-to-cycle standard deviations (SD) of a large selection of shoulder and elbow kinematic variables, were processed using principal component analysis (PCA). Thereafter, between-subjects and between-days (within-subject) variance components were calculated using a random effects model for each of four extracted principal components. The results showed that MV differed consistently between subjects (95% confidence intervals of the between-subjects variances did not include zero) and that subjects differed consistently in MV between days. Thus, our results support the notion that MV may be a consistent personal trait, even though further research is needed to verify whether individuals rank consistently in MV even across tasks. If so, MV may be a candidate determinant of the risk of developing fatigue and musculoskeletal disorders in repetitive occupational work.

  • 653.
    Sandlund, Jonas
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research. Department for Community Medicine and Rehabilitation, Umeå University.
    Srinivasan, Divya
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Consistency of individual motor variability patterns in repetitive precision work2015In: Physiotherapy, ISSN 0031-9406, E-ISSN 1873-1465, Vol. 101, no Suppl. 1, p. e1334-e1335Article in journal (Other academic)
    Abstract [en]

    Background:

    A longstanding hypothesis in physical therapy and occupational research is that workers repeating a task very stereotypically will be more prone to develop musculoskeletal disorders than workers that manage to vary postures and loads. Increased movement variability (MV), presumably, modify tissue loads, distribute stresses more equally, and thus reduce the cumulative load on any particular tissue. A handful of studies of MV have indicated less overuse injuries and faster recovery from musculoskeletal pain disorders. Even when repeating strictly controlled tasks individuals may differ in motor consistency, some showing higher levels of MV than others. However, whether the extent of MV is indeed a consistent individual trait across different tasks and different days is not known.

    Purpose:

    To investigate whether individual profiles of MV is stabile between days, the consistency of MV patterns from kinematic recordings, repeated across three days, was studied when performing repetitive upper-extremity precision work.

    Methods:

    A laboratory-based simulation of precision work; a 'pipetting' task paradigm, was developed in which liquid was repeatedly transferred from one tube to another, with a cycle time of 2.8s. Fourteen healthy female subjects, aged 20-45 years, right-handed and with experience in pipetting participated on 3 different days under identical conditions. Kinematic data were obtained using an electromagnetic motion capture system (FASTRAK). MV in shoulder elevation, elbow flexion and shoulder-elbow coordination were operationalized using cycle-to-cycle standard deviations across 20 pipetting cycles of kinematics parameters including joint range of motion, average and peak velocities, time to peak velocities, average angle and phase. Multivariate analysis was conducted using principal component analysis (PCA) (SIMCA+P, 12.0) to analyze relationships among variables and individual patterns in the data matrix of the recordings from day1. Thereafter, in order to confirm the observed structure of inter-individual MV patterns, classification of the data from day2 and day3 was performed using the parameters of the model from day1.

    Results:

    Four PCA components (Eigenvalues>1) accounted for 80 percent of the total variance in the model for day1. In the subsequent prediction model where data from day2 and 3 were projected into the model of day1, all subject observations except one could be predicted with 95% confidence (Hotelling T2). And individual data scores from all three days were clustered in relative proximity to each other, indicating consistency in MV between days.

    Conclusion(s):

    The findings indicate, even in this small and homogenous sample of young healthy females, that there may indeed be consistent individual traits in motor variability. A next step would be to answer whether these traits remain consistent if work factors such as work pace or precision are altered, and whether individual profiles of MV are associated with physiological responses related to risk for developing musculoskeletal disorders.

    Implications:

    Consistency of individual MV patterns substantiate previous notions that some people appear prone to repeat themselves while others tend to vary their motor behavior when performing the same task. Assessment of MV by physical therapists in research and practice could be valuable to further explore and address the relation of MV and musculoskeletal health.

  • 654.
    Sato, Tatiana
    et al.
    Physical Therapy Department, Federal University of São Carlos (UFSCar), Brazil.
    Hallman, David
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Kristiansen, Jesper
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    Holtermann, Andreas
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    The association between multisite musculoskeletal pain and cardiac autonomic modulation during work, leisure and sleep - a cross-sectional study2018In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 19, no 1, article id 405Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    The prevention and rehabilitation of multisite musculoskeletal pain would benefit from studies aiming to understand its underlying mechanism. Autonomic imbalance is a suggested mechanism for multisite pain, but hardly been studied during normal daily living. Therefore, the aim of the study is to investigate the association between multisite musculoskeletal pain and cardiac autonomic modulation during work, leisure and sleep.

    METHODS:

    This study is based on data from the "Danish Physical activity cohort with objective measurements" among 568 blue-collar workers. Pain intensity scales were dichotomized according to the median of each scale, and the number of pain sites was calculated. No site was regarded as the pain-free, one site was considered as single-site musculoskeletal pain and pain in two or more sites was regarded as multisite musculoskeletal pain. Heart rate variability (HRV) was measured by an electrocardiogram system (ActiHeart) and physical activity using accelerometers (Actigraph). Crude and adjusted linear mixed models were applied to investigate the association between groups and cardiac autonomic regulation during work, leisure and sleep.

    RESULTS:

    There was no significant difference between groups and no significant interaction between groups and domains in the crude or adjusted models for any HRV index. Significant differences between domains were found in the crude and adjusted model for all indices, except SDNN; sleep time showed higher values than leisure and work time, except for LF and LF/HF, which were higher during work.

    CONCLUSION:

    This cross-sectional study showed that multisite musculoskeletal pain is not associated with imbalanced cardiac autonomic regulation during work, leisure and sleep time.

  • 655.
    Sato, Tatiana
    et al.
    Physical Therapy Department, Federal University of São Carlos (UFSCar), Brazil.
    Hallman, David
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Kristiansen, Jesper
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    Skotte, Jørgen
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    Holtermann, Andreas
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    Different autonomic responses to occupational and leisure time physical activities among blue-collar workers2018In: International Archives of Occupational and Environmental Health, ISSN 0340-0131, E-ISSN 1432-1246, Vol. 91, no 3, p. 293-304Article in journal (Refereed)
    Abstract [en]

    PURPOSE:

    The differential effect of occupational and leisure time physical activity on cardiovascular health is termed the physical activity health paradox. Cardiac autonomic modulation could bring insights about the underlying mechanism behind this differential effect. The aim was to compare heart rate variability (HRV) during different activities (sitting, standing and moving) at work and leisure among blue-collar workers.

    METHODS:

    One hundred thirty-eight workers from the NOMAD cohort were included. Data from physical activity and HRV were obtained for 3-4 days using tri-axial accelerometers (Actigraph GT3X+) and a heart rate monitor (Actiheart). HRV indices were determined during sitting, standing and moving both at work and leisure. Linear mixed-models with two fixed factors (activities and domains) were applied to investigate differences in HRV indices adjusting for individual and occupational factors.

    RESULTS:

    The results showed significant effects of domain (p < 0.01), physical activity type (p < 0.01) and interaction between domain and activity type (p < 0.01) on HRV indices. Mean heart rate (IBI) and parasympathetic measures of HRV (RMSSD and HF) were lower for sitting (p < 0.01) and higher for moving (p < 0.01) during work compared with leisure, while no difference between domains was found for standing (p > 0.05). Sympathovagal balance (LF/HF) was higher during work for sitting and moving (p < 0.01), but showed no difference for standing (p = 0.62).

    CONCLUSIONS:

    Differences in cardiac autonomic modulation between work and leisure were found, indicating sympathetic predominance during work and parasympathetic predominance during leisure for sitting. Autonomic responses can be part of the mechanism that explains the differential effect of occupational and leisure time physical activity on health.

  • 656.
    Sato, Tatiana
    et al.
    Physical Therapy Department, Federal University of São Carlos, São Paulo, Brazil.
    Hallman, David
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Kristiansen, Jesper
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    Skotte, Jørgen
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    Holtermann, Andreas
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    Different autonomic responses to occupational and leisure time physical activity among blue-collar workers2016Conference paper (Refereed)
    Abstract [en]

    Introduction: There is a well-established relationship between high physical activity at leisure time and decreased mortality risk. On the other hand, high physical demands at work seem to increase this risk. However, the underlying mechanism behind this effect remains unknown. Heart rate variability (HRV) measurements may bring some insight into the mechanism. Thus, the aim of this study was to determine whether HRV differs between work and leisure time among blue-collar workers.

    Methods: This study was based on data from the cross-sectional NOMAD study among blue-collar workers from seven workplaces in Denmark. One hundred thirty-eight blue-collar workers, which had at least 7 recording hours during work and leisure time were included in the analysis. Data from physical activity and HRV were obtained for four days using tri-axial accelerometers (Actigraph GT3X+) and heart rate monitor (Actiheart), respectively. Parametric (paired t test) and nonparametric (Wilcoxon signed-ranks test) tests for pairwise comparisons were applied to compare mean HRV indices in time and frequency domains between work and leisure time.

    Results: The mean age of the workers was 45.2 years, 51% were females, 42% were smokers, 18% reported lifetime occurrence of hypertension and 45% reported to perform lifting and carrying for more than half of the work time. A significant higher overall HRV was found during leisure time compared to work. Leisure time showed higher parasympathetic nervous system (PNS) measures of HRV (p<.05), while sympathetic nervous system (SNS) related indices (p<.05) were reduced in comparison to work.

    Conclusions: Leisure time showed high HRV and PNS indices and work time showed high SNS-related indices. The higher SNS modulation during work can be related to a greater risk of developing heart diseases among blue-collar workers.

  • 657.
    Schomburg, Eike D.
    et al.
    Zentrum Physiologie und Pathophysiologie, Universität Göttingen, Göttingen, Germany.
    Steffens, Heinz
    Zentrum Physiologie und Pathophysiologie, Universität Göttingen, Göttingen, Germany.
    Maznychenko, Andrey V.
    Department of Movement Physiology, Bogomoletz Institute of Physiology, National Academy of Sciences, Kiev, Ukraine.
    Pilyavskii, Alexander I.
    Department of Movement Physiology, Bogomoletz Institute of Physiology, National Academy of Sciences, Kiev, Ukraine.
    Hellström, Fredrik
    University of Gävle, Centre for Musculoskeletal Research.
    Kostyukov, Alexander I.
    Department of Movement Physiology, Bogomoletz Institute of Physiology, National Academy of Sciences, Kiev, Ukraine.
    Maisky, Vladimir A.
    Department of Movement Physiology, Bogomoletz Institute of Physiology, National Academy of Sciences, Kiev, Ukraine.
    Acute muscle inflammation enhances the monosynaptic reflexes and c-fos expression in the feline spinal cord2007In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 11, no 5, p. 579-586Article in journal (Refereed)
    Abstract [en]

    The aim of this research was to study the changes of the motor reflex activity (monosynaptic reflex (MSR) of the flexor and extensor muscles) and Fos immunoreactivity in lumbo-sacral spinal cord after acute induced myositis of m. gastrocnemius-soleus (GS). The experiments were carried out on ischaemic decerebrated, spinalized in C1 cats. After infiltration of the GS muscle with carrageenan (2%) MSRs of flexors and extensors showed a significant increase in amplitude +127+/-24.5% and +155+/-28.5%, respectively, p<0.05. The exposed effect was initiated within 30 min and achieved a maximum 2.8h after the intramuscular injections of carrageenan. After analysis of dynamics of the MSRs, animals were perfused and c-fos expression in the spinal segments L6-S1 was evaluated. In comparison to sham-operated animals, the number of Fos-immunoreactive (Fos-ir) cells was noticeably increased in the lumbar cord of cats with carrageenan-induced myositis. The labeled cells were concentrated in the ipsilateral laminae I/II, neck of the dorsal horn (V/VI) and intermediate zone (VII), however, clear predominance of their concentration was found in the deep laminae. The effect of muscle inflammation was also expressed as a significant decline in the number of NADPH-d-reactive cells (p<0.05) in ipsilateral laminae I/II of L6/L7. The results show that the input from acutely inflamed muscles may induce an increase of the reflex responsiveness of flexors and extensors which is not mediated via the gamma-spindle-loop and which coincides with a significant increase in c-fos expression in the deep laminae of the lumbar spinal cord.

  • 658.
    Sjölander, Per
    University of Gävle, Centre for Musculoskeletal Research.
    Samernas hälsa och livssituation2009In: Omvårdnad i mångkulturell rum: frågor om kultur, etik och reflektion / [ed] Björngren Cuadra, Carin, Lund: Studentlitteratur , 2009, p. 181-212Chapter in book (Refereed)
  • 659.
    Sjölander, Per
    et al.
    University of Gävle, Centre for Musculoskeletal Research. Southern Lapland Research Department, Postgatan 7, SE-912 32 Vilhelmina, Sweden.
    Daerga, Laila
    University of Gävle, Centre for Musculoskeletal Research. Southern Lapland Research Department, Vilhelmina, Sweden.
    Edin-Liljegren, Anette
    Southern Lapland Research Department, Vilhelmina, Sweden.
    Jacobsson, L.
    Division of Psychiatry, Department of Clinical Sciences, Umeå University, Umeå, Sweden.
    Musculoskeletal symptoms and perceived work strain among reindeer herders in Sweden2008In: Occupational Medicine, ISSN 0962-7480, E-ISSN 1471-8405, Vol. 58, no 8, p. 572-579Article in journal (Refereed)
    Abstract [en]

    Background There is a shortage of knowledge on the extent of musculoskeletal symptoms in reindeer husbandry.

    Aims To investigate the prevalence and relative risk for musculoskeletal symptoms and perceived psychosocial work strain among reindeer herders.

    Methods The prevalence of self-reported musculoskeletal symptoms during the last week and last year, respectively, were obtained from male reindeer herders (n574) of northern Sweden. Prevalence ratios (PRs) were calculated using two reference groups—women of reindeer-herding families (n5 53) and men in blue-collar occupations (n 5 194). Comparisons were made of perceived job strain between the study and reference groups. Associations between job strain factors and the occurrence of musculoskeletal symptoms from different body regions were analysed with regression statistics.

    Results The PRs for musculoskeletal symptoms from the hand/wrist (PR 3.48, 95% CI 1.86–6.50) and lower back (PR 1.44, 95% CI 1.06–1.95) were significantly higher among the reindeer herders in comparison with men working with other blue-collar occupations. The reindeer herders reported significantly higher work demands and decision latitude compared with both reference groups (P , 0.05). Significant associations were observed between demands and prevalence of symptoms from the lower back (OR 1.42, 95% CI 1.01–2.01) and from at least one body region (OR 1.58, 95% CI 1.07–2.32).

    Conclusions The relative risk for musculoskeletal symptoms, particularly from the hands/wrists and lower back, was high among reindeer herders. It is suggested that musculoskeletal symptoms constitute a considerable health problem in modern reindeer husbandry, which calls for implementation of preventive measures addressing psychosocial, physical and socio-economic risk factors.

  • 660.
    Sjölander, Per
    et al.
    University of Gävle, Centre for Musculoskeletal Research. Southern Lapland Research Department, Vilhelmina, Sweden.
    Hassler, Sven
    Southern Lapland Research Department, Vilhelmina, Sweden; Department of Nursing, Health and Culture, University West, Trollhättan, Sweden.
    Janlert, Urban
    epartment of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
    Stroke and acute myocardial infarction in the Swedish Sami population: incidence and mortality in relation to income and level of education2008In: Scandinavian Journal of Public Health, ISSN 1403-4948, E-ISSN 1651-1905, Vol. 36, no 1, p. 84-91Article in journal (Refereed)
    Abstract [en]

    Background: Gender differences in cardiovascular diseases (CVD) among the Sami have been reported previously. The aim of the present study was to investigate the incidence of and mortality from stroke, subarachnoid haemorrhage (SAH) and acute myocardial infarction (AMI) in the Swedish Sami population between 1985 and 2002, and to analyse the potential impact of income and level of education on the cardiovascular morbidity and mortality.

    Methods: A Sami cohort of 15,914 persons (4,465 reindeer herding and 11,449 non-herding Sami) were followed from 1985 to 2002 with respect to incidence and mortality rates of AMI, stroke and SAH. Incidence and mortality ratios were calculated using a demographically matched non-Sami control population (DMC) as the standard (71,550 persons).

    Results: There was no elevated risk for developing AMI among the Sami compared with the DMC. However, the mortality ratio of AMI was significantly higher for Sami women. Higher incidence rates of stroke and SAH for both Sami men and women was observed, but no differences in mortality rates. Apart from the reindeer herding men who demonstrated lower levels of income and education, the income and education levels among Sami were similar to the DMC.

    Conclusions: High mortality rates from AMI rather than stroke explain the excess mortality for CVD previously shown among Sami women. The results suggest that the differences in incidence of stroke between herding and non-herding Sami men, and between Sami women and non-Sami women, are caused by behavioural and psychosocial risk factors rather than by traditional socioeconomic ones.

  • 661.
    Sjölander, Per
    et al.
    University of Gävle, Centre for Musculoskeletal Research. Southern Lapland Research Department, Vilhelmina, Sweden.
    Michaelson, Peter
    University of Gävle, Centre for Musculoskeletal Research. Department of Surgery and Perioperative Sciences, Division of Sports Medicine, University of Umeå, Sweden; Department of Health Science, Physiotherapy Unit, Luleå University of Technology, Luleå, Sweden.
    Jaric, Slobodan
    University of Gävle, Centre for Musculoskeletal Research. Human Performance Laboratory, University of Delaware, DE, USA.
    Djupsjöbacka, Mats
    University of Gävle, Centre for Musculoskeletal Research.
    Sensorimotor disturbances in chronic neck pain: range of motion, peak velocity, smoothness of movement, and repositioning acuity2008In: Manual Therapy, ISSN 1356-689X, E-ISSN 1532-2769, Vol. 13, no 2, p. 122-131Article in journal (Refereed)
    Abstract [en]

    The purpose of this pilot study was to evaluate sensorimotor functions in patients with chronic neck pain with objective and quantitative methods. A group of 16 patients with chronic idiopathic neck pain of insidious onset or whiplash associated disorders (WAD) was compared to an equally sized group of healthy subjects. Kinematics were investigated during voluntary head rotations by measuring range of motion, variability of range of motion (ROM-Variability), peak velocity, and smoothness of movement (jerk index). Repositioning acuity after cervical rotations was evaluated by analysing constant and variable error (VE). In comparison to the healthy subjects, the patients showed significantly larger jerk index, ROM-Variability and VE. No statistically significant differences were found between insidious neck pain and WAD. It is concluded that jerky and irregular cervical movements and poor position sense acuity are characteristic sensorimotor symptoms in chronic neck pain. The observed individuality in sensorimotor disturbances emphasizes the importance of developing specific rehabilitation programs for specific dysfunctions, and of using objective and quantitative methods for evaluation of rehabilitation.

  • 662. Slijper, H P
    et al.
    Mathiassen, Svend Erik
    University of Gävle, Centre for Musculoskeletal Research.
    Hoozemans, M
    Over, E A B
    Richter, J
    Time aspects of computer use across one year of exposure: metrics and empirical findings2008In: Proceedings of the International Conference on Ambulatory Monitoring of Physical Activity and Movement, 2008Conference paper (Other academic)
  • 663.
    Slijper, Harm
    et al.
    Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Over, E.
    Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands.
    Richter, Janneke
    Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands.
    Frens, Maarten
    Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands.
    Measuring computer use behavior: patterns of variability, within and across days and between different users2008In: Proceedings of Measuring Behavior 2008; 6th International Conference on Methods and Techniques in Behavioral Research / [ed] A.J. Spink, M.R. Ballintijn, N.D. Bogers, F. Grieco, L.W.S. Loijens, L.P.J.J. Noldus, G. Smit, and P.H. Zimmerman, Wageningen: Noldus , 2008, p. 111-112Conference paper (Refereed)
  • 664.
    Srinivasan, Divya
    et al.
    Department of Industrial and Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, USA.
    Barbieri, Dechristian
    Department of Physical Therapy, Federal University of São Carlos, São Paulo, Brazil.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Oliveira, Ana Beatriz
    Department of Physical Therapy, Federal University of São Carlos, São Paulo, Brazil.
    Sit-stand desks with reminder prompts and semi-automated position changes2017Conference paper (Refereed)
  • 665.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Cantu, Hiram
    Department of Kinesiology and Physical Education, McGill University.
    Cote, Julie
    Department of Kinesiology and Physical Education, McGill University.
    Fatigue-induced increase in movement variability does not come at a cost of worse performance in a repetitive pointing task2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203Article in journal (Refereed)
    Abstract [en]

    Neuromuscular strategies employed in multijoint movements during repetitive motion-induced fatigue are still unclear, and movement variability may present a novel way to understand the compensatory control mechanisms that occur during fatigue. The aim of this study was to assess changes in shoulder and elbow joint kinematic variabilities and shoulder-elbow coordination variability associated with neck-shoulder fatigue, and whether these changes affected the spatio-temporal aspects of task performance. Nineteen healthy young adults continuously performed a repetitive pointing task between two targets placed in front of them at shoulder height at 1 Hz until fatigue (Borg CR10 rating of 8). Shoulder and elbow kinematics were recorded and used to compute shoulder abduction-adduction and elbow flexion-extension joint angles, and fingertip trajectories were used to compute the movement time and 3D spatial coordinates of the endpoint in each repetitive pointing movement cycle. Cycle-to-cycle movement variability of the shoulder and elbow joint angles from 15 consecutive forward pointing movements and cycle-to-cycle variability of continuous relative phase between the shoulder and elbow joint angles were compared between the first (baseline) and last (fatigue-terminal) minutes of performance. Shoulder kinematic variability and shoulder-elbow coordination variability were found to significantly increase with fatigue (by 60% and 30% of their respective baseline values). However, movement timing errors and spatial variability of the endpoint were found to be unchanged with fatigue. Results suggest that fatigue-related increase in shoulder variability may have been compensated by changes in shoulder-elbow coordination with an overall task performance objective and associated hierarchical control mechanisms.

  • 666.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Martin, Bernard
    University of Michigan.
    Does the Central Nervous System learn to plan bimanual movements based on its expectation of availability of visual feedback2012In: Human Movement Science, ISSN 0167-9457, E-ISSN 1872-7646, Vol. 31, no 6, p. 1409-1424Article in journal (Refereed)
    Abstract [en]

    The correlation between gaze strategy and kinematics of bimanual movements isassessed using repetitive bimanual object transfers as an experimental paradigm. The hypothesis isthat visual demand in such tasks may be a critical bottleneck determining bimanual coordination.Kinematics and eye-movements were compared before and after practice of this repetitive task.New eye-hand coordination strategies emerged with practice. Also, with practice, a systematicprioritization of the left hand movement to be „primary‟ and the right hand movement to be„secondary‟ emerged. This choice implied that the left hand movement kinematics was similar tounimanual left hand movements, whereas the performance of the right hand task was contingent onsuccessful completion of the primary task. This was revealed by „anticipatory adjustments‟ of theright hand kinematics (Right-hand peak velocity ranged from 100%-70% of the left-hand, and thescaling was dependent on task conditions and the corresponding eye-hand coordination strategiesused). We use this evidence to argue that the CNS, aware of an inherent asymmetry between thetwo hand systems, learns to anticipate the need and availability of visual feedback for successfultask completion, and uses this knowledge to optimize movement coordination - specifically suchthat the right-hand control was modulated to take visual constraints into account.

  • 667.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Martin, Bernard
    University of Michigan, Ann Arbor, USA.
    Emergence of Visuomotor Coordination with Training in Bimanual Movements2012In: Proceedings of the Twelfth International Symposium on the 3D Analysis of Human Movement, 2012Conference paper (Refereed)
  • 668.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Martin, Bernard
    University of Michigan, Ann Arbor, USA.
    Reed, Matthew
    University of Michigan, Ann Arbor, USA.
    Effects of task characteristics on unimanual and bimanual movement times2013In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 56, no 4, p. 612-622Article in journal (Refereed)
    Abstract [en]

    Fitts’ law cannot be used to predict movement times (MTs) of bimanual tasks since no empirical relationships associating task difficulty and bimanual MT have been demonstrated yet. Development of a ‘bimanual task difficulty index’ has been challenged by the complex patterns of coordination involved in simultaneously performing two tasks, one with each hand, under a control system with limited visual and attentional resources. To address this fundamental issue in human motor performance, bimanual object transfers with the left and right hands to targets of various precision requirements and separated by different distances were studied in six healthy subjects. Visual resource allocation during task performance was used to identify ‘primary’ and ‘secondary’ hand movements in bimanual tasks. While the primary movement was similar to a unimanual movement, the secondary MT varied with its own, as well as the contralateral hand’s task constraints. These results, which were stable and consistent across six subjects, provide preliminary evidence that visual behaviour, indicating closed-loop control, can be used to systematically derive bimanual MTs.

  • 669.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Motor variability in occupational health and performance2012In: Clinical Biomechanics, ISSN 0268-0033, E-ISSN 1879-1271, Vol. 27, no 10, p. 979-993Article in journal (Refereed)
    Abstract [en]

    Several recent reviews have reported that 'repetitive movements' is a risk factor for occupational musculoskeletal disorders (MSD) in the neck, shoulder and arm regions. More variation in biomechanical exposure is often suggested as an effective intervention in such settings. Since increasing variation using extrinsic methods like job rotation may not always be possible in an industrial context, the intrinsic variability of the motor system may offer an alternative opportunity to increase variation. Motor variability (MV) refers to the natural variation in postures, movements and muscle activity observed to different extents in all tasks. The current review discusses relevant MV research appearing in motor control, sports sciences and occupational biomechanics literature to answer whether MV is important to consider in an occupational context, and if yes, whether it can be manipulated by training the worker or changing the working conditions so as to increase biomechanical variation without jeopardizing production

  • 670.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Motor variability – an important issue in occupational life2012In: Work: A journal of Prevention, Assesment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, Vol. 41, no Suppl. 1, p. 2527-2534Article in journal (Refereed)
    Abstract [en]

    Several recent reviews have reported that ‘repetitive movements’ is a risk factor for occupational musculoskeletal disorders (MSD) in the neck, shoulder and arm regions. More variation in biomechanical exposure is often suggested as an effective intervention in such settings. While increasing variation using extrinsic methods like job rotation may not always be possible in an industrial context, the intrinsic variability of the motor system may offer an alternative opportunity to increase variation. Motor variability (MV) refers to the natural variation in postures, movements and muscle activity observed to different extents in all tasks. The current review explores the state of the art in MV research from motor control, sports and occupational biomechanics literature to answer whether MV is important to consider in an occupational context, and if yes, whether this literature stimulates further studies to test if MV can be manipulated as a deliberate intervention for increasing biomechanical variation without jeopardizing production.

  • 671.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    The consistency across days of motor variability in repetitive pipetting2013In: Eighth International Conference on Prevention of Work-related Musculoskeletal Disorders; Abstracts, 2013, p. 56-57Conference paper (Refereed)
  • 672.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    The effect of combining physical and cognitive loads on motor variability in a standardised repetitive precision task2015In: Proceedings of the 19th Triennial Congress of the International Ergonomics Association, Melbourne 9-14 August, 2015 / [ed] Gitte Lindgaard & Dave Moore, 2015Conference paper (Refereed)
  • 673.
    Srinivasan, Divya
    et al.
    Grado Department of Industrial and Systems Engineering, Virginia Polytechnic Institute and State University.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Barbieri, Dechristian
    Department of Physical Therapy, Federal University of São Carlos.
    Oliveira, Ana Beatriz
    Department of Physical Therapy, Federal University of São Carlos.
    Do sit-stand workstations increase variation in upper arm postures while performing computer-intensive office work?2017Conference paper (Refereed)
  • 674.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Hallman, David M.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Samani, Afshin
    SMI, Department of Health Science and Technology, Aalborg University, Denmark.
    Madeleine, Pascal
    SMI, Department of Health Science and Technology, Aalborg University, Denmark.
    Lyskov, Eugene
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Effects of concurrent physical and cognitive demands on muscle activity and heart rate variability in a repetitive upper-extremity precision task2016In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, no 1, p. 227-239Article in journal (Refereed)
    Abstract [en]

    Purpose Most previous studies of concurrent physical and cognitive demands have addressed tasks of limited relevance to occupational work, and with dissociated physical and cognitive task components. This study investigated effects on muscle activity and heart rate variability of executing a repetitive occupational task with an added cognitive demand integral to correct task performance.

    Methods Thirty-five healthy females performed 7.5 min of standardized repetitive pipetting work in a baseline condition and a concurrent cognitive condition involving a complex instruction for correct performance. Average levels and variabilities of electromyographic activities in the upper trapezius and extensor carpi radialis (ECR) muscles were compared between these two conditions. Heart rate and heart rate variability were also assessed to measure autonomic nervous system activation. Subjects also rated perceived fatigue in the neck–shoulder region, as well as exertion.

    Results Concurrent cognitive demands increased trapezius muscle activity from 8.2 % of maximum voluntary exertion (MVE) in baseline to 9.0 % MVE (p = 0.0005), but did not significantly affect ECR muscle activity, heart rate, heart rate variability, perceived fatigue or exertion.

    Conclusion Trapezius muscle activity increased by about 10 %, without any accompanying cardiovascular response to indicate increased sympathetic activation. We suggest this slight increase in trapezius muscle activity to be due to changed muscle activation patterns within or among shoulder muscles. The results suggest that it may be possible to introduce modest cognitive demands necessary for correct performance in repetitive precision work without any major physiological effects, at least in the short term.

  • 675.
    Srinivasan, Divya
    et al.
    Grado Department of Industrial and Systems Engineering, Virginia Polytechnic Institute and State University.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Huysmans, Maaike
    Department of Public & Occupational Health; EMGO Institute for Health & Care Research, VU University Medical Center, Amsterdam.
    Between-subjects and between-days variance in occupational sitting time among seasoned users of sit-stand workstations2017Conference paper (Refereed)
  • 676.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Samani, Afshin
    Department of Health Science and Technology, Aalborg University.
    Madeleine, Pascal
    Department of Health Science and Technology, Aalborg University.
    Effects of concurrent physical and cognitive demands on arm movement kinematics in a repetitive upper-extremity precision task2015In: Human Movement Science, ISSN 0167-9457, E-ISSN 1872-7646, Vol. 42, p. 89-99Article in journal (Refereed)
    Abstract [en]

    The effect of concurrent physical and cognitive demands on arm motor control is poorly understood. This exploratory study compared movement kinematics in a repetitive high-precision pipetting task with and without additional concurrent cognitive demands in the form of instructions necessary to locate the correct target tube. Thirty-five healthy female subjects performed a standardized pipetting task, transferring liquid repeatedly from one pick-up tube to different target tubes. In the reference condition, lights indicated the target tube in each movement cycle, while the target tube had to be deciphered from a row and column number on a computer screen in the condition with additional cognitive demands. Kinematics of the dominant arm was assessed using the central tendency and variability of the pipette-tip end-point trajectory and joint kinematics properties of the shoulder and elbow. Movements slowed down (lower velocities and higher area under the movement curves) and end point trajectory variability increased in the condition with additional cognitive demands, but there were no changes in the kinematics properties such as joint range of motion, times of acceleration and deceleration (as indicated by the time to peak velocity), average angles, or phase relationships between angle and angular velocity of shoulder or elbow movements between the two conditions. Further, there were also no differences in the size or structure of variability of the shoulder and elbow joint angles, suggesting that subjects could maintain the motor repertoire unaltered in the presence of these specific additional cognitive demands. Further studies should address motor control at other levels of concurrent cognitive demands, and with motor tasks that are less automated than the pipetting task used in the present study, so as to gain an increased understanding of the effect of concurrent cognitive demands for other activities of relevance to daily life.

  • 677.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Samani, Afshin
    Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Denmark.
    Madeleine, Pascal
    Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Denmark.
    The combined influence of task accuracy and pace on motor variability in a standardised repetitive precision task2015In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 58, no 8, p. 1388-1397Article in journal (Refereed)
    Abstract [en]

    Thirty-five healthy women, experienced in pipetting, each performed four pipetting sessions at different pace and accuracy levels relevant to occupational tasks. The size and structure of motor variability of shoulder and elbow joint angles were quantified using cycle-to-cycle standard deviations of several kinematics properties, and indices based on sample entropy and recurrence quantification analysis. Decreasing accuracy demands increased both the size and structure of motor variability. However, when simultaneously lowering the accuracy demand and increasing pace, motor variability decreased to values comparable to those found when pace alone was increased without changing accuracy. Thus, motor variability showed some speed-accuracy trade-off, but the pace effect dominated the accuracy effect. Hence, this trade-off was different from that described for end-point performance by Fitts’ law. The combined effect of accuracy and pace and the resultant decrease in motor variability are important to consider when designing sustainable work systems comprising repetitive precision tasks.

  • 678.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Rudolfsson, Thomas
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research. Department of Community Medicine and Rehabilitation, Umeå University, Umeå, Sweden.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Between- and within-subject variance of motor variability metrics in females performing repetitive upper-extremity precision work2015In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 25, no 1, p. 121-129Article in journal (Refereed)
    Abstract [en]

    Kinematic motor variability is extensively studied in occupational, clinical and sports biomechanics, but the consistency of most motor variability metrics have never been reported. In this study, fourteen subjects performed a repetitive pipetting task on three separate days. Movements of hand, arm and pipette tip were recorded in 3D and used to compute shoulder elevation, elbow flexion and shoulder-arm coordination angles, as well as pipette-tip endpoint precision. Cycle-to-cycle motor variability was quantified using linear dispersion measures of standard kinematics properties such as peak velocity, range of motion, and inter-segmental relative phase. Between- and within-subject consistencies of these variability metrics were quantified by variance components estimated using a nested random effects model. For most metrics, the variance between subjects was larger than that between days and cycles. Entering the variance components in statistical power equations showed that for most metrics, a total of 80-100 subjects will be required to detect a 20% difference between two groups with sufficient power, while this difference can typically be detected  in repeated-measures (paired) designs using 25 subjects. The reported between- and within-subject variance components can be used as a data base to facilitate efficient designs of future studies of kinematic motor variability.

  • 679.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Samani, Afshin
    Center for Sensorimotor Interaction, Department of Health Science and Technology, Aalborg University.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Madeleine, Pascal
    Center for Sensorimotor Interaction, Department of Health Science and Technology, Aalborg University.
    The size and structure of arm movement variability decreased with work pace in a standardised repetitive precision task2015In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 58, no 1, p. 128-139Article in journal (Refereed)
    Abstract [en]

    Increased movement variability has been suggested to reduce the risk of developing musculoskeletal disorders caused by repetitive work. This study investigated the effects of work pace on arm movement variability in a standardized repetitive pipetting task performed by 35 healthy women. During pipetting at slow and fast paces differing by 15%, movements of arm, hand and pipette were tracked in 3D, and used to derive shoulder and elbow joint angles. The size of cycle-to-cycle motor variability was quantified using standard deviations of several kinematics properties, while the structure of variability was quantified using indices of sample entropy and recurrence quantification analysis. When pace increased, both the size and structure of motor variability in the shoulder and elbow decreased. These results suggest that motor variability drops when repetitive movements are performed at increased paces, which may in the long run lead to undesirable outcomes such as muscle fatigue or over-use.

  • 680.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Sandlund, Jonas
    Umeå University, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Motor variability traits among individuals performing repetitive precision work2014In: Proceedings of the 11th International Symposium on Human Factors in Organizational Design and Management (ODAM), and 46th Annual Nordic Ergonomics Society Conference (NES): Selected and peer reviewed papers / [ed] Ole Broberg et al., Santa Monica, CA: The IEA Press , 2014, p. 987-989Conference paper (Refereed)
    Abstract [en]

    Motor variability (MV) refers to the intrinsic variability naturally present in the motor control system. Occurring even in the simplest movements, it is usually manifested as a difference in joint movements, joint coordination and/or muscle activities between successive repeats of a task which are identical in performance. Contrary to the traditional view that MV is detrimental to performance, it is now widely accepted that MV may actually have an important functional role in skill acquisition, and that skilled performance may, actually, be associated with increased MV. Further, MV is related to pain and fatigue, and may play a decisive role in rehabilitation (reviewed in Srinivasan & Mathiassen 2012). Hypothetically, individuals with a larger MV would be better protected against overuse injuries, and recover faster after disorders affecting motor performance. However, whether the extent of MV is, indeed, a consistent individual trait across different tasks is not known.    

    The purpose of this study was to let individuals perform a laboratory-based simulation of repetitive upper-extremity precision work and determine:

    (i)             Whether it is possible to systematically classify individuals according to the size of their MV in repetitive work;

    (ii)            Whether classification of individuals in one working condition on one day persists even when some work-factors are slightly changed, and between different days when they perform the same work.

    Repetitive pipetting with a cycle time of 2.8s was performed in the laboratory by a group of 14 healthy female subjects, aged 20-45 years, right-handed and experienced in pipetting, on 3 different days under identical protocol and experimental conditions. Work factors such as work-pace, precision and cognitive load (on top of the pipetting work) were manipulated within each day. Kinematic data were obtained using electromagnetic motion capture systems (FASTRAK).

    MV in shoulder elevation, elbow flexion and shoulder-elbow coordination were operationalized using cycle-to-cycle standard deviations of motor parameters such as peak velocities, time lag of peak velocities, phase angle and inter-segmental phase angle. The resulting traits in individuals and the consistency of those traits across tasks and days will be presented.

  • 681.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Sinden, Kathryn
    Department of Kinesiology and Physical Education, McGill University, Montréal.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Coté, Julie
    Department of Kinesiology and Physical Education, McGill University, Montréal.
    Gender differences in muscle activity responses to a fatiguing short-cycle repetitive task2016Conference paper (Refereed)
    Abstract [en]

    Background. More women suffer from musculoskeletal disorders (MSDs) in the neck-shoulder and hand-arm regions than men, even when they are performing similar jobs. Fatigue is a known predictor of MSDs, and gender differences in fatigue responses could help explain the difference in MSD occurrence. This study aimed to assess the extent to which genders differ in fatigability by examining muscle-activity responses when perform-ing a low-force, repetitive arm-task leading to muscle fatigue in the neck-shoulder region.

    Methods. 108 healthy individuals (55 males, 53 females) repeatedly touched two targets placed at shoulder height in front of them. The targets were placed at 30% and 100% of arm’s length and touched at a rate established by a 1Hz metronome until the subjects reported a perceived exertion of 8 on the Borg CR-10 scale for the neck-shoulder region. Bipolar surface EMG was recorded from the upper trapezius, anterior deltoid, biceps and triceps. Task duration and EMG amplitude (average and cycle-to-cycle variability) during the first minute (baseline) and last minute (fatigue-terminal) were compared between men and women.

    Results. There were no gender differences in task duration, EMG variability at baseline, or change in average EMG amplitude with fatigue. Change in EMG variability from baseline to fatigue-terminal was lower for women than men in the upper trapezius (7.2% vs. 30.6% increase, p=0.02), and higher for women than men in the biceps (11.8% increase vs. 23.2% decrease, p=0.0006).

    Discussion.This is the first study to report gender differences in muscle-activity responses to a fatiguing, dynamic manual task relevant to working life based on a comprehensive sample of healthy individuals. Despite no differences in task duration, there may be gen-der differences in the physiological mechanisms behind fatigue adaptations: while women may use compensatory mechanisms mainly involving the elbow, men may use more shoulder-driven strategies. These gender differences in muscle-activity responses may contribute to explaining why women suffer more from neck-shoulder MSDs than men.

  • 682.
    Srinivasan, Divya
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research. Grado Department of Industrial and Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, United States.
    Sinden, Kathryn
    McGill University, Montreal, Canada; CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, Canada.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Côté, Julie
    McGill University, Montreal, Canada; CRIR Research Centre, Jewish Rehabilitation Hospital, Laval, Canada.
    Gender differences in muscle activity responses and fatigability to a short-cycle repetitive task2016In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, no 11-12, p. 2357-2365Article in journal (Refereed)
    Abstract [en]

    Purpose: Epidemiological research has identified women to be more susceptible to developing neck-shoulder musculoskeletal disorders when performing low-force, repetitive work tasks. Whether this is attributable to gender differences in fatigability and motor control is currently unclear. This study investigated the extent to which women differ from men in fatigability and motor control while performing a short-cycle repetitive task.

    Methods: 113 healthy young adults (58 women, 55 men) performed a standardized repetitive pointing task. The task was terminated when the subject's perceived exertion reached 8 on the Borg scale. Time to task termination, and changes in means and cycle-to-cycle variabilities of surface electromyography signals from start to end of the task were compared between women and men, for the upper trapezius, anterior deltoid, biceps and triceps muscles.

    Results: Women and men terminated the task after 6.5 (SD 3.75) and 7 (SD 4) min on average (p>0.05). All 4 muscles showed an increase of 25-35% in average muscle activity with fatigue (no significant sex differences). However, men exhibited a higher increase than women in trapezius muscle variability with fatigue (31% vs. 7%; p<0.05), and a decrease in biceps muscle variability where women had an increase (-23% vs. 12%; p<0.05).

    Conclusions: Our results suggest that women and men may not differ in the ability to perform repetitive tasks at low-to-moderate force levels. However, differences in motor control strategies employed in task performance may explain gender differences in susceptibility to developing musculoskeletal disorders when performing repetitive work for prolonged periods in occupational life.

  • 683.
    Staats, Henk
    et al.
    Department of Social and Organizational Psychology, Leiden University, Leiden, The Netherlands.
    Jahncke, Helena
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Herzog, Tom
    Department of Psychology, Grand Valley State University, Allendale, MichiganUSA.
    Hartig, Terry
    Institute for Housing and Urban Research, Uppsala University, Uppsala, Sweden.
    Urban options for psychological restoration: common strategies in everyday situations2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 1, article id e0146213Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES:Given the need for knowledge on the restorative potential of urban settings, we sought to estimate the effects of personal and contextual factors on preferences and restoration likelihood assessments for different urban activities-in-environments. We also sought to study the generality of these effects across different countries.

    METHODS:We conducted a true experiment with convenience samples of university students in the Netherlands (n = 80), Sweden (n = 100), and the USA (n = 316). In each country, the experiment had a mixed design with activities-in-environments (sitting in a park, sitting in a cafe, walking in a shopping mall, walking along a busy street) manipulated within-subjects and the need for restoration (attentional fatigue, no attentional fatigue) and immediate social context (in company, alone) manipulated between-subjects. The manipulations relied on previously tested scenarios describing everyday situations that participants were instructed to remember and imagine themselves being in. For each imagined situation (activity-in-environment with antecedent fatigue condition and immediate social context), subjects provided two criterion measures: general preference and the likelihood of achieving psychological restoration.

    RESULTS:The settings received different preference and restoration likelihood ratings as expected, affirming that a busy street, often used in comparisons with natural settings, is not representative of the restorative potential of urban settings. Being with a close friend and attentional fatigue both moderated ratings for specific settings. Findings of additional moderation by country of residence caution against broad generalizations regarding preferences for and the expected restorative effects of different urban settings.

    CONCLUSIONS:Preferences and restoration likelihood ratings for urban activity-environment combinations are subject to multiple personal and contextual determinants, including level of attentional fatigue, being alone versus in company, and broader aspects of the urban context that vary across cities and countries. Claims regarding a lack of restorative quality in urban environments are problematic.

  • 684.
    Stensdotter, Ann-Katrin
    et al.
    Umeå University, Umeå, Sweden; Sør-Trøndelag University College, Trondheim, Norway.
    Bjerke, Joakim
    Umeå University, Umeå, Sweden; Sør-Trøndelag University College, Trondheim, Norway.
    Djupsjöbacka, Mats
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Postural sway in single-limb and bilateral quiet standing after unilateral total knee arthroplasty2015In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 41, no 3, p. 769-773Article in journal (Refereed)
    Abstract [en]

    Aim: To investigate whether total knee arthroplasty (TKA) was associated with stability in single-limb stance and whether reduced stability in single-limb stance was associated with increased postural sway in bilateral quiet standing. Methods: 3D kinematics for center of mass was used to assess postural sway in 23 subjects with TKA and 23 controls. Tests included bilateral quiet standing with and without vision and on a compliant surface, and single-limb stance. Results: 30% of the subjects in the TKA group were unable to maintain single-limb stance for 20. s on any leg. Of the 70% in the TKA group able to stand on one leg, mean sway velocity in the medio-lateral direction was marginally higher for the prosthetic side (p = .02), but no differences were found between the TKA and the control group in single-limb stance. Performance in bilateral quiet standing was similar in TKA-subjects, able as well as unable to stand on one leg, and controls. Reduced quadriceps strength in the contralateral leg, higher BMI, and older age predicted failure to maintain single-limb stance. Conclusion: In subjects able to stand on one leg, performance was considered comparable between the prosthetic and contralateral side and between groups. Inability to stand on one leg did not affect postural sway in bilateral quiet standing. The results suggest that inability to maintain single-limb stance is explained by reduced physical capacity rather than the knee condition in itself. The present study emphasizes the importance of physical activity to improve strength and functional capacity.

  • 685. Stensdotter, Ann-Katrin
    et al.
    Lorås, Håvard W.
    Fløvig, John Christian
    Djupsjöbacka, Mats
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Postural control in quiet standing in patients with psychotic disorders2013In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 38, no 4, p. 918-922Article in journal (Refereed)
    Abstract [en]

    There is evidence that patients with psychotic conditions display greater center of pressure (CoP) displacement during quite standing than healthy subjects, but the underlying impairments in the control mechanisms are uncertain. The aim of this study was to identify the nature of possible impairments in the control of posture by modulation of visual and kinesthetic information during quiet standing. Center of pressure (CoP) data and whole-body kinematics of the center of mass (CoM) were recorded during quite standing on a firm surface with eyes open and with eyes closed, and standing with eyes open on a yielding surface. During all three conditions, patients displayed greater migration of CoM and CoP-CoM, a measure related to ankle joint torque, whereas CoP-frequency (MPF) was similar in patients and healthy subjects. Our results suggested that greater postural sway in patients may depend on disproportionally large ankle joint torque without corresponding increase in frequency. Furthermore, interactions between groups and conditions suggested that the patients made less use of visual information for postural control than the healthy subjects.

  • 686.
    Stevens, Matthew
    et al.
    The National Research Centre for the Working Environment, Denmark.
    Crowley, Patrick
    The National Research Centre for the Working Environment, Denmark.
    Lund Rasmussen, Charlotte
    National research centre for the working environment, Denmark.
    Hallman, David
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational Health Science and Psychology, Occupational Health Science. University of Gävle, Centre for Musculoskeletal Research.
    Mortensen, Ole
    Section of Social Medicine, Department of Public Health, University of Copenhagen, Denmark.
    Nygård, Clas-Håkan
    Unit of Health Sciences, Faculty of Social Science, Tampere University, Finland.
    Holtermann, Andreas
    The National Research Centre for the Working Environment, Denmark.
    Accelerometer-measured physical activity at work and need for recovery: A compositional analysis of cross-sectional data2019In: Annals of Work Exposures and Health, ISSN 2398-7308Article in journal (Refereed)
    Abstract [en]

    Objectives

    Previous research has shown strong associations between occupational physical activity (OPA) and need for recovery (NFR). However this research has only utilized self-reported measures of OPA which may be biased. Thus, there is a need for investigating if the previously documented association between self-reported OPA and NFR can be found when using technical measures of OPA. There is also the need to investigate whether older workers are particularly susceptible to increased NFR, since age-related declines in physical capacity mean that it is likely these workers will have a higher NFR for a given physical activity. The aim of this study was to investigate the association between technically measured OPA and NFR, and whether this relationship is modified by age.

    Methods

    This study utilized data from the Danish Physical Activity Cohort with Objective Measurements cohort—comprising Danish workers (n = 840) from the cleaning, manufacturing, and transportation sectors. OPA was measured by accelerometers attached to the thigh and upper back for at least one work day and classified into four physical behaviour categories (sedentary, standing, light, or moderate/vigorous). NFR was measured using a shortened version of the Danish NFR scale. Analysis was conducted using linear regression and isotemporal substitution analyses for compositional data.

    Results

    The overall association between OPA and NFR was statistically significant in the unadjusted model (P < 0.001), but not when adjusted for age, sex, occupation, and shift work (P = 0.166). Isotemporal substitution showed small but significant reductions in NFR when increasing sedentary time relative to other behaviours (adjusted: ΔNFR = −0.010 [−0.019; −0.001]). There were no significant interactions between age and OPA (P = 0.409).

    Conclusions

    This study found significant associations between OPA and NFR, but the effect sizes were small. Reallocating 30 min to sedentary behaviours from other behaviours was associated with a reduced NFR, but the effect size may not be practically relevant. Moreover, no clear modifying effects of age were identified.

  • 687.
    Straker, Leon
    et al.
    Curtin University, Perth.
    Abbott, Rebecca
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Heiden, Marina
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Toomingas, Allan
    Institute of Environmental Medicine, Karolinska Institutet.
    Sit-stand desks and sedentary behavior in Swedish call centre workers2012In: Be active 2012, 2012, p. S94-Conference paper (Refereed)
    Abstract [en]

    Introduction: Adults spend approximately 8 to 9 hours of the day in sedentary behavior and much of this is gathered at work. The rising level of occupational sedentary behavior is both a public health and occupational health concern due to the emerging evidence regarding the deleterious effect that sedentary behavior has on health, independent of physical activity. In the occupational setting, sit-stand desks have been purported to offer a means of reducing sedentariness. This study aimed to investigate whether or not use of sit-stand desks and awareness of the importance of postural variation and breaks are associated with the pattern of sedentary behavior in call centre workers.

    Method: The data came from a cross-sectional observation study of fifteen Swedish call centres, carried out in 2002–2003. Ten operators were randomly selected from each of the call centres and invited to participate. Inclinometers recorded ‘seated’ or ‘standing/walking’ episodes of the operators over a full work shift. Differences in sedentary behavior based on desk type (categorized as ‘sit-stand’ or ‘sit’) and awareness of the importance of posture variation and breaking up seated computer work within those using a sit-stand desk were assessed by non-parametric analyses.

    Results: Four operators declined to participate and 15 operators had inclinometer recordings that were not of sufficient quality. Of the remaining 131 operators, 90 (68.7%) worked at a sit-stand desk. Working at a sit-stand desk, as opposed to a sit desk, was associated with a modest reduction in the time seated (78.5 vs 83.8%, p = 0.010), and less time taken to accumulate 5 minutes of standing/walking (36.2 vs 46.3 minutes, p = 0.022), but no significant difference to sitting episode length or the number of switches between sitting and standing/walking per hour. Ergonomics awareness had no significant association with any sedentary behavior pattern variable among those using a sit-stand desk.

    Conclusion: Use of sit-stand desks was associated with better sedentary behavior in call centre workers, however ergonomics awareness did not enhance the effect. The growing number of people in occupations dominated by sedentary work and the clear evidence of the importance of sedentary behavior as a key lifestyle risk factor support the need to develop effective interventions. Sit-stand desks may be an important remedy in this endeavor, particularly in office settings, while ergonomics awareness may be able to contribute to further changes in sedentary behavior if improved and supported by the work organization.

  • 688.
    Straker, Leon
    et al.
    School of Physiotherapy, Curtin University, Perth.
    Abbott, Rebecca
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Heiden, Marina
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Toomingas, Allan
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Sit-stand desks, ergonomics awareness and sedentariness in Swedish call centres2012Conference paper (Refereed)
  • 689.
    Straker, Leon
    et al.
    School of Physiotherapy, Curtin University, Perth, Australia.
    Abbott, Rebecca
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Heiden, Marina
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Toomingas, Allan
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Sit-stand desks in call centres: associations of use and ergonomics awareness with sedentary behavior2013In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 44, no 4, p. 517-522Article in journal (Refereed)
    Abstract [en]

    Objective. Sedentary behavior is an independent risk factor for obesity, diabetes, and all cause mortality. With adults in occupational settings spending two thirds or more of their time in sedentary behavior, novel strategies are required to intervene with occupational sitting. To investigate whether or not use of sit-stand desks and awareness of the importance of postural variation and breaks are associated with the pattern of sedentary behavior in office workers.

    Method. The data came from a cross-sectional observation study of Swedish call centre workers. Inclinometers recorded ‘seated’ or ‘standing/walking’ episodes of 131 operators over a full work shift. Differences in sedentary behavior based on desk type and awareness of the importance of posture variation and breaks were assessed by non-parametric analyses.

    Results. 90 (68.7%) operators worked at a sit-stand desk. Working at a sit-stand desk, as opposed to a sit desk, was associated with less time seated (78.5 vs 83.8%, p=0.010), and less time taken to accumulate 5 minutes of standing/walking (36.2 vs 46.3 minutes, p=0.022), but no significant difference to sitting episode length or the number of switches between sitting and standing/walking per hour. Ergonomics awareness was not associated with any sedentary pattern variable among those using a sit-stand desk.

    Conclusion. Use of sit-stand desks was associated with better sedentary behavior in call centre workers, however ergonomics awareness did not enhance the effect. Further investigation into how best to intervene with occupational sitting is required.

  • 690.
    Straker, Leon
    et al.
    Curtin University, Perth.
    Abbott, Rebecca
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Teaching our children to sit or be active? Sedentary behavior, light activity and moderate/vigorous activity at and away from school2012In: 4th International Congress on Physical Activity and Public Health, Australian Conference of Science and Medicine in Sport, National Sports Injury Prevention Conference Abstracts, 2012, p. S280-Conference paper (Refereed)
    Abstract [en]

    Introduction: Sedentary behavior in children is associated with poor health whilst moderate/vigorous activity is associated with better health. The school setting may be an opportunity to reduce sedentariness and enhance physical activity, yet concerns have been raised that children may be more sedentary at school. This paper examined activity patterns, including both sedentary time and time in health enhancing physical activity, in children across their typical week.

    Methods: Sixty-six 10–12 year old children were recruited from 48 schools in the Perth metropolitan area as part of a randomized controlled study (Australia and New Zealand Clinical Trials Registry ACTRN 12609000279224) investigating the effects of electronic games on physical activity. The data for this paper come from their baseline assessment, which all occurred during school term time. Children wore an Actical accelerometer on their hip for one week. Time spent in sedentary, light, moderate and vigorous physical activity was assessed. School day and weekend day activity patterns were examined along with activity patterns both in (school time) and out of school (non-school-time) on school days.

    Results: Valid (at least 4 days) accelerometer data were available on 53 children (28 girls). The average time of accelerometer recording per day was 822 ± 71 minutes (13.7 hours). Accumulated time in sedentary behavior was similar on school days and weekend days (mean [SD]: 64.4%[5.3] vs 64.9%[9.0], p = 0.686). Children were more likely to reach physical activity guidelines on school days than at the weekend (47.7% v 22.2%, p < 0.001) and spend more time in brief–less than 5 minutes–bursts of activity of any intensity (35.3%[5.1] vs 32.6%[6.9], p = 0.002). However, children spent a higher proportion of time in sedentary behavior (66.8%[7.3] vs 62.4%[5.2], p < 0.001), and significantly more time in extended sedentariness–sedentary for more than thirty minutes or more (75.6mins[45.8] vs 45.0 mins[26.8], p < 0.002)–within school time compared to non-school time.

    Discussion: Children spent a considerable proportion of their school or non-school day in sedentary behavior, and routinely spent over two hours of each day in extended sedentary behavior. School should be a place where children learn healthful habits, and whilst it appears to be associated with better moderate/vigorous physical activity exposure it was associated with poorer extended sedentary exposure. Increasing moderate/vigorous physical activity and reducing time spent in sedentary behavior both in and out of school remains an important challenge.

  • 691.
    Straker, Leon
    et al.
    Curtin University, Perth.
    Campbell, Amity
    Curtin University, Perth.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Abbott, Rebecca
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Parry, Sharon
    Curtin University, Perth.
    Davey, Paul
    Curtin University, Perth.
    Capturing the pattern of activity: Exposure variation analysis of accelerometer data2012In: 4th International Congress on Physical Activity and Public Health, Australian Conference of Science and Medicine in Sport, National Sports Injury Prevention Conference Abstracts, 2012, p. S94-S94Conference paper (Refereed)
    Abstract [en]

    Purpose: Physical activity, in particular moderate to vigorous physical activity (MVPA), sedentary behaviour (SB) are known to impact on health. Less well established is how patterning of activity affects health. Capturing the complex time pattern of activity using accelerometry remains a challenge. Occupational health research suggests Exposure Variation Analysis (EVA) could provide a useful tool. The purpose of this paper is to 1) explain the application of EVA to accelerometer data, 2) demonstrate how EVA thresholds, derivatives could be chosen, used to examine adherence to MVPA, SB guidelines, 3) explore the validity of EVA outputs.

    Methods: EVA reduces a complex time-line of exposure into a two-dimensional matrix showing combinations of exposure level (in categories) and duration of uninterrupted sequences (in categories). Data from 4 individuals with different daily activity patterns were collected to demonstrate the applicability of EVA. EVA outputs were also compared for accelerometer data collected from 3 occupational groups with known different activity patterns: seated workstation office workers, standing workstation office workers and teachers. Standard accelerometer data collection procedures were used. Data processing by a custom LabVIEW program calculated EVA matrices and derivatives aligned to common guidelines.

    Results: Data from one individual is presented in a time-based line graph form in conjunction with the resultant EVA matrix and EVA graph. Line graphs and related EVA graphs for 3 further individuals highlight the use of EVA derivatives for examining compliance with MVPA and SB guidelines. For the seated office workers, standing office workers and teachers, analyses confirm no difference in bouts of MVPA but very clear differences as expected in extended bouts of SB and brief bursts of activity, thus providing evidence of construct validity of the EVA approach.

    Conclusion: The major advantage of EVA is its ability in a single analysis to simultaneously capture the time pattern of activity at various levels of intensity according to the choice of the researcher. Whilst presented here with four levels of intensity, sedentary, light, moderate and vigorous, EVA could be utilised with dichotomous data such as sitting vs standing, or adjusted to match future refinements of activity guidelines. EVA offers a unique and comprehensive generic method that is ideal for processing large quantities of accelerometer data. EVA is able, for the first time, to concisely capture the time pattern (both frequency and intensity) of activity, and can be tailored for both occupational and public health research.

  • 692.
    Straker, Leon
    et al.
    Curtin University, Perth.
    Campbell, Amity
    Curtin University, Perth.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Abbott, Rebecca
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Parry, Sharon
    Curtin University, Perth.
    Davey, Paul
    Curtin University of Technology, Perth.
    Capturing the pattern of physical activity and sedentary behavior: Exposure Variation Analysis of accelerometer data2014In: Journal of Physical Activity and Health, ISSN 1543-3080, E-ISSN 1543-5474, Vol. 11, no 3, p. 614-625Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Capturing the complex time pattern of physical activity (PA) and sedentary behavior (SB) using accelerometry remains a challenge. Research from occupational health suggests exposure variation analysis (EVA) could provide a meaningful tool. This paper (1) explains the application of EVA to accelerometer data, (2) demonstrates how EVA thresholds and derivatives could be chosen and used to examine adherence to PA and SB guidelines, and (3) explores the validity of EVA outputs.

    METHODS: EVA outputs are compared with accelerometer data from 4 individuals (Study 1a and1b) and 3 occupational groups (Study 2): seated workstation office workers (n = 8), standing workstation office workers (n = 8), and teachers (n = 8).

    RESULTS: Line graphs and related EVA graphs highlight the use of EVA derivatives for examining compliance with guidelines. EVA derivatives of occupational groups confirm no difference in bouts of activity but clear differences as expected in extended bouts of SB and brief bursts of activity, thus providing evidence of construct validity.

    CONCLUSIONS: EVA offers a unique and comprehensive generic method that is able, for the first time, to capture the time pattern (both frequency and intensity) of PA and SB, which can be tailored for both occupational and public health research.

  • 693.
    Straker, Leon
    et al.
    School of Physiotherapy and Exercise Science, Curtin University, Perth.
    Hall, Caitlin
    The University of Queensland, School of Human Movement and Nutrition Sciences, Brisbane.
    Holtermann, Andreas
    National Research Centre for the Working Environment, Copenhagen.
    van der Beek, Allard
    Department of Public and Occupational Health, Amsterdam Public Health Research Institute, VU University Medical Centre, Amsterdam.
    Huijsmans, Maaike
    Department of Public and Occupational Health, Amsterdam Public Health Research Institute, VU University Medical Centre, Amsterdam.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Gilson, Nicholas
    The University of Queensland, School of Human Movement and Nutrition Sciences, Brisbane.
    Blue‐collar worker sedentary exposure at work and non‐work: systematic review of studies using objective measurement2018Conference paper (Refereed)
  • 694.
    Straker, Leon
    et al.
    School of Physiotherapy and Exercise Science, Curtin University, Perth.
    Hallman, David
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Gupta, Nidhi
    National Research Centre for the Working Environment, Copenhagen.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Holtermann, Andreas
    National Research Centre for the Working Environment, Copenhagen.
    The Goldilocks Principle: Innovative work design for improved health2018Conference paper (Refereed)
  • 695.
    Straker, Leon
    et al.
    School of Physiotherapy, Curtin University of Technology, Perth Australia.
    Mathiassen, Svend Erik
    University of Gävle, Centre for Musculoskeletal Research. University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences.
    Increased physical work loads in modern work - a necessity for better health and performance?2009In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 52, no 10, p. 1215-1225Article in journal (Refereed)
    Abstract [en]

    Shifting workforce proportions to sedentary occupations and technology developments in traditionally physically demanding occupations have resulted in low physical workloads for many workers. Insufficient physical stress is known to have detrimental short- and long-term effects on health and physical capacity. It is argued herein that many modern workers are at risk of insufficient physical workload. Further, it is argued that the traditional physical ergonomics paradigm of reducing risk by reducing physical loads ('less is better') is not appropriate for many modern occupations. It is proposed that a new paradigm is required, where 'more can be better'. The potential for work to be seen as an arena for improving physical health and capability is discussed and the types of changes to work that may be required are outlined. The paper also discusses challenges and responsibilities presented by this new paradigm for ergonomists, employers, health and safety authorities and the community. The majority of workers in affluent communities now face the significant threat to health of insufficient physical workload. Ergonomics can design work to a prescription that can not only reduce injury risk but enhance health and capacity. However, this will require a change in paradigm.

  • 696.
    Straker, Leon
    et al.
    School of Physiotherapy, Curtin University, Perth, Australia.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Holtermann, Andreas
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    The ‘Goldilocks Principle’: designing physical activity at work to be ‘just right’ for promoting health2018In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 52, no 13, p. 818-819Article in journal (Refereed)
  • 697.
    Stratimirovic, Dj.
    et al.
    Faculty of Stomatology, Department of Physics, University of Belgrade, Belgrade, Serbia and Montenegro.
    Milosevic, S.
    Faculty of Physics, University of Belgrade, Belgrade, Serbia and Montenegro.
    Blesic, S.
    Institute for Medical Research, Laboratory for Neurophysiology, Belgrade, Serbia and Montenegro.
    Ljubisavljevic, M.
    University of Gävle, Centre for Musculoskeletal Research.
    Wavelet transform analysis of time series generated by the stimulated neuronal activity2007In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 374, no 2, p. 699-706Article in journal (Refereed)
    Abstract [en]

    We have studied the stimulated discharge dynamics of fusimotor neurons by applying the wavelet transform technique and by adopting that the neuronal discharge dynamics is manifested by the random time series of interspike intervals. We found two different power-law type behaviors along interspike intervals (ISI) time scale (which implies existence of two different types of neuronal noise), which are separated by a crossover region. Our results reveal that complex neuronal dynamics, in the presence of external stimulation, is manifested with long-range correlated noise in the region before the crossover, on the ISI time scale.

  • 698.
    Strömberg, Annika
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational Health Science and Psychology, Occupational Health Science. University of Gävle, Centre for Musculoskeletal Research.
    Engström, Maria
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Science, Caring Science.
    Hagerman, Heidi
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Science, Caring Science.
    Skytt, Bernice
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Science, Caring Science.
    First-line managers dealing with different management approaches2019In: Leadership in Health Services, ISSN 1751-1879, E-ISSN 1751-1887, Vol. 32, no 4, p. 543-557Article in journal (Refereed)
    Abstract [en]

    Purpose – The purpose of this paper is to contribute new knowledge about how first line managers (FLMs) in elderly care perceive their situation, with a focus on differences in management approaches at the intersection of the central and local parts of the organization.

    Design/methodology/approach – The present study has a qualitative approach and is part of a larger project on FLMs in elderly care. The results presented here are based on a secondary analysis of 15 of the totalof 28 interviews carried out in the project.

    Findings – Themain results are twofold: the majority of FLMs perceived differences in management approaches between local and central management; the differences caused some struggle because FLMs perceived that the management system did not support the differences. The two main aspects that caused the FLMs to struggle were differences in the foci of the management levels and difficulties in influencing the conditions ofmanagement.

    Originality/value – The results contribute to the debate on what aspects are important to sustainable management of elderly care. It is common knowledge that FLMs have a complex position, intermediate to the central, upper level management and their subordinates at the local level – levels with different foci and interests. The study contributes new knowledge about what these differences consist of and the dilemmas they cause and offers suggestions as to what can be done to reduce both energy waste and the risk of low job satisfaction.

  • 699.
    Svedberg, Pia
    et al.
    Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    Mather, Lisa
    Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    Bergström, Gunnar
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research. Division of Intervention and Implementation Research for Worker Health, The Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Lindfors, Petra
    Department of Psychology, Stockholm University, Stockholm, Sweden.
    Blom, Victoria
    Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Department of Psychology, Stockholm University, Stockholm, Sweden; The Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Time pressure and sleep problems due to thoughts about work as risk factors for future sickness absence2018In: International Archives of Occupational and Environmental Health, ISSN 0340-0131, E-ISSN 1432-1246, Vol. 91, no 8, p. 1051-1059Article in journal (Refereed)
    Abstract [en]

    PURPOSE: This study investigated whether time pressure or sleep problems due to thoughts about work are associated with future sickness absence (SA) among women and men employed in different sectors, also when adjusting for confounders including familial factors (genetics and shared environment).

    METHODS: The study sample included 16,127 twin individuals (52% women), aged 19-47 years who in 2005 participated in an online survey including questions regarding time pressure, sleep, work and health. Register data on SA (> 14 days) were obtained from the National Social Insurance Agency and individuals were followed from date of survey response until 12/31/2013. Associations between time pressure, sleep problems due to thoughts about work and future SA were investigated using logistic regression analyses to assess odds ratios (OR) with 95% confidence intervals (CI).

    RESULTS: In total 5723 (35%) individuals had an incident SA spell during follow-up. Sleep problems due to thoughts about work were associated with SA in the fully adjusted model (OR 1.22, CI 1.10-1.36). Stratified by sector, the highest estimate was found for state employees (OR 1.54, CI 1.11-2.13). Familial factors did not seem to influence the associations. We found no statistically significant associations between time pressure and SA. No sex differences were found.

    CONCLUSIONS: Results indicated that sleep problems due to thoughts about work is a risk factor for future SA. This follows previous research showing that sleep length and sleep disturbances, regardless of reason, are associated with SA. But, experiences of work-related time pressure seem to have no effect on SA.

  • 700.
    Svedmark, Åsa
    et al.
    Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
    Björklund, Martin
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research. Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
    Häger, Charlotte K.
    Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
    Nilsson Sommar, Johan
    Department of Public Health & Clinical Medicine, Occupational and Environmental Medicine, Umeå University, Umeå, Sweden.
    Wahlström, Jens
    Department of Public Health & Clinical Medicine, Occupational and Environmental Medicine, Umeå University, Umeå, Sweden.
    Impact of Workplace Exposure and Stress on Neck Pain and Disabilities in Women: A Longitudinal Follow-up After a Rehabilitation Intervention2018In: Annals of Work Exposures and Health, ISSN 2398-7316, Vol. 62, no 5, p. 591-603Article in journal (Refereed)
    Abstract [en]

    Introduction: The aim was to evaluate if pain, disability, and work productivity are influenced by physical and psychosocial work exposures as well as by stress, up to 1 year after a randomized controlled trial treatment intervention, and to determine whether any such association differed between treatment and control groups.

    Methods: Ninety-seven working women suffering non-specific neck pain (n = 67 treatment group, n = 30 control group) were followed from end of treatment intervention and at 9- and 15-month follow-ups, respectively. Physical and psychosocial exposures, as well as perceived stress, were assessed after the treatment intervention. Pain, neck disability, and work productivity were assessed at baseline, after intervention 3 months later and at 9- and 15-month follow-ups. Longitudinal assessment was conducted using the exposure level at 3 months as predictor of pain, disability, and work productivity at 3, 9, and 15 months, respectively. Mixed models were used to estimate longitudinal associations, accounting for within-individual correlation of repeated outcome measures by incorporation of a random intercept. Age and duration of neck pain were adjusted for in all models. To evaluate group differences, interactions between exposures and treatment groups were estimated.

    Results: High perceived stress was associated with more neck pain, more neck disability, and decreased work productivity in both cross-sectional and longitudinal analyses. High 'control of decision' was associated with less neck pain, less neck disability, and higher work productivity in cross-sectional analyses but only to less disability and higher productivity in longitudinal analyses. Shoulder/arm load was the only physical exposure variable that was significantly associated with work productivity in the univariate analyses. Only small differences were observed between treatment and control groups.

    Conclusion: High perceived stress and low 'control of decision' were associated with more neck pain, increased neck disability, and decreased work productivity. Treatment interventions for individuals with neck pain should take into account psychosocial workplace exposures and stress to improve intermediate and long-term results.

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