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  • 1.
    Aasa, Ulrika
    University of Gävle, Belastningsskadecentrum.
    Ambulance work: relationships between occupational demands, individual characteristics and health-related outcomes2005Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Although musculoskeletal disorders (MSDs) and other health cornplaints are an occupational problem for ambulance personnel, there is a lack ofknowJedge regarding work-related factors associated with MSDs and other health cornplaints. The overall aim ofthis thesis was to investigate the relationships between occupational demands, individual characteristics and health-related outcornes among ambulance personnel.

    A random sarnple of 234 female and 953 male ambulance personnel participated in a national questionnaire suTVey on work-related factors, and musculoskeletal and other health cornplaints. Physical demands was associated with activity limitation due to neck-shoulder and low-back complaints among the female personnel. Among the male personnel, physical demands was associated with low-back cornplaints and activity limitation due to low-back cornplaints. Psychological demands was significantly associated with neck-shoulder complaints, sleeping problerns, headache and stomach syrnptorns among both female and male ambulance personnel. Worry about work conditions was associated with musculoskeletal disorders and sleeping problerns, headache and stomach symptoms.

    A local sample of 26 ambulance personnel was followed during a 24-hour work shift and for the next two work-free days. Subjective stress- and energy levels, and cortisol levels were measured at regular inteTYals, and heart rate was registered continuously by electrocardiogram (ECG). Autonomic reactivity to standardized tests before (pre-work) and at the end of the work shift (post-work) was also investigated. For the whole group, baseline values of heart rate were higher pre-work than post-work, but autonomic reactivity did not differ. lncreased reactivity to the mental test, modest deviation in heart rate variability (HRV) pattem during the Jate night hours at work and higher moming cortisol values during work than during leisure time were obseTVed in personnel with many health cornplaints, but not among their co-workers without or with few complaints. Ambulance personnel with many health complaints also reported higher psychological demands and tended to be more worried about work conditions.

    Heart rate (HR), lactate level (LL) and perceived exertion (RPE) were investigated in 17 female and 48 male ambulance personnel during a simulated standardized work task "carry a loaded stretcher". The ambulance personnel had to carry the loaded stretcher (920 N) up and down three tlights of stairs twice. The high physiological strain (HR, LL, RPE) for the male, and near or at maximal strain for the female ambulance personnel, implied the importance to identify what kind of physical capacity is most important for ambulance personnel. Therefore, the explained variance of developed fatigue by tests of cardiorespiratory capacity, muscular strength and endurance, and coordination was investigated. The results showed that VO2max and isometric back endurance were important predictors for development of fatigue when carrying a loaded stretcher .

    The influence of body size on the relationships between maximal strength and functional performance was investigated in a methodological study. The results confirm that the assessment ofphysical performance could be confounded by the body weight. Therefore, the models for explaining development of fatigue when carrying the loaded stretcher were adjusted for height and weight. lncluding height in the models significantly increased the exp1ained variance of accumulated lactate among female, but not among male personnel. Lactate levels were higher among short cornpared to tall female personnel. Weight had no effect on any of the models.

    In conclusion, the national suTVey showed that self-reported physical demands was a risk factor of having MSDs, and that self-reported psychological demands and worry about work were important risk factors of having MSDs and other health complaints. Stress monitoring of ambulance personnel during work and leisure time showed that physiological and subjective stress markers did not show any differences between the 24-hour ambulance work shift and leisure time afterwards. However, ambulance personnel with many health cornplaints had certain physiological changes during the work shift in cornparison with the next two work-free days. The physiological and subjective responses during carrying a loaded stretcher, especially among the female ambulance personnel, showed that female and male ambulance personnel could be exposed to intemal exposures at different levels when performing the same work task. A better understanding of the relationships between occupational demands and health-related ou tcomes require further studies on age- and gender matched groups in long-term perspective studies.

  • 2.
    Aasa, Ulrika
    et al.
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Angquist, Karl-Axel
    Brulin, Christine
    Relationships between work-related factors and disorders in the neck-shoulder and low-back region among female and male ambulance personnel2005In: Journal of Occupational Health, ISSN 1341-9145, Vol. 47, no 6, 481-489 p.Article in journal (Refereed)
    Abstract [en]

    This cross-sectional study on a random sample of 1,500 ambulance personnel investigated the relationships between self-reported work-related physical and psychosocial factors, worry about work conditions, and musculoskeletal disorders among female and male ambulance personnel. Three different outcomes, complaints, activity limitation, and sick leave, for the neck-shoulder and low-back region, respectively, were chosen. Among the female personnel, physical demands was significantly associated with activity limitation in the neck-shoulder (OR 4.13) and low-back region (OR 2.17), and psychological demands with neck-shoulder (OR 2.37) and low-back (OR 2.28) complaints. Among the male personnel, physical demands was significantly associated with low-back complaints (OR 1.41) and activity limitation (OR 1.62). Psychological demands and lack of social support were significantly associated with neck-shoulder complaints (OR 1.86 and OR 1.58, respectively) and activity limitation (OR 3.46 and OR 1.71) as well as activity limitation due to low-back complaints (OR 2.22 and OR 1.63). Worry about work conditions was independently associated with activity limitation due to low-back complaints among the female (OR 5.28), and to both neck-shoulder and low-back complaints (OR 1.79 and OR 2.04, respectively) and activity limitation (OR 2.32 and OR 1.95) among the male personnel. In conclusion, the association patterns between physical and psychological demands and MSDs suggest opportunities for intervention.

  • 3.
    Aasa, Ulrika
    et al.
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Jaric, Slobodan
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Normalisation of muscle strength for body size: The role of the function assessed2004In: Journal of Human Movement Studies, ISSN 0306-7297, Vol. 46, no 2, 105-116 p.Article in journal (Refereed)
    Abstract [en]

    The role of body size has often been neglected in routine tests of muscle strength and movement performance. The aim of the present study was to test the hypothesis that different types of functional movement performance require different normalisations in order to assess muscle strength. Twenty-one right-handed male university students were tested on the following functional movement tasks: vertical jump, standing soccer ball kick, seated medicine ball throw and standing maximal isometric lift. Isokinetic strength of active muscle \, groups was also recorded. The performance of the vertical jump and standing s9ccer ball kick demonstrated stronger relationship with the strength of active muscles normalised for body size, while the performance of the s~ated medicine ball throw and standing maximal

    Iisometric lift demonstrated stronger relationship with the non- normalised strength.

    It was concluded that the ability of performing functional movements based on overcoming gravitational and/or inertial resistance of subject's own body (such as keeping certain body postures, or various body movements) should be assessed by the tested muscle strength normalised for body size, while the functional performance based on muscle action performed against external objects (e.g. manual material handling, or lifting heavy objects) should be assessed by the non-normalised muscle strength. The obtained f"mdings proved to be in line with our recently proposed classification of muscle strength and functional movement tests based on the role of body size in the re~orded performance.

  • 4.
    Aasa, Ulrika
    et al.
    University of Gävle, Belastningsskadecentrum.
    Brulin, Christine
    Angquist, Karl-Axel
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Work-related psychosocial factors, worry about work conditions and health complaints among female and male ambulance personnel.2005In: Scandinavian Journal of Caring Sciences, ISSN 0283-9318, E-ISSN 1471-6712, Vol. 19, no 3, 251-258 p.Article in journal (Refereed)
    Abstract [en]

    This study aimed at investigating the relationships between work-related psychosocial factors, worry about work conditions and health complaints (sleeping problems, headache and stomach symptoms) among female and male ambulance personnel. Out of 4000 ambulance personnel in Sweden, 1500 (300 female and 1200 male personnel) were randomly selected. They answered a questionnaire including items on self-reported health complaints, individual characteristics, work-related psychological demands, decision latitude, social support and worry about work conditions. Twenty-five per cent of the female and 20% of the male ambulance personnel reported two or more health complaints sometimes or often. According to the demand-control-support questionnaire, ambulance personnel reported a generally positive psychosocial work environment, although psychological demands were associated with sleeping problems, headache and stomach symptoms among both female and male ambulance personnel. Another factor that was significantly associated with health complaints among both genders was worry about work conditions. When worry about work conditions was added to the regression models, this variable took over the role from psychological demands as a predictor for health complaints among the female ambulance personnel. The prevalence of sleeping problems, headache and stomach symptoms were significantly associated with psychological demands among both female and male ambulance personnel. Notably, worry about work conditions seems to be an important risk factor for health complaints. This suggests that worry about work conditions should not be neglected when considering risk factors among ambulance personnel.

  • 5.
    Aasa, Ulrika
    et al.
    University of Gävle, Belastningsskadecentrum.
    Kalezic, Nebojsa
    University of Gävle, Belastningsskadecentrum.
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Samband mellan självrapporterad stress, salivkortisol och musculoskelettala besvär: Självrapporteringsmetoder i stressforskning2004In: Stress-conference, 2004Conference paper (Other (popular science, discussion, etc.))
  • 6. Albert, Frederic
    et al.
    Ribot-Ciscar, Edith
    Fiocchi, Michel
    Bergenheim, Mikael
    University of Gävle, Belastningsskadecentrum.
    Roll, Jean-Pierre
    Proprioceptive feedback in humans expresses motor invariants during writing.2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 164, no 2, 242-9 p.Article in journal (Refereed)
    Abstract [en]

    Proprioceptive feedback from populations of muscle spindle afferents feeds the brain with information relating to the instantaneous velocity and direction of ongoing movements. In this paper, we investigate whether the invariant relationship between the velocity and curvature of a trajectory, i.e. the two-thirds power law, is reflected in this muscle spindle feedback. Sixty unitary muscle spindle afferents from six ankle muscle groups were recorded using intraneural microelectrodes during imposed "writing-like" movements. The movements had kinematic parameters obeying the two-thirds power law and were imposed so that the tip of the foot followed trajectories forming four different letters and six numbers. The responses of the muscle spindle afferent populations were analysed using the population vector model. The results demonstrate that the neuronal trajectories attained from populations of muscle spindles clearly depict the path and kinematic parameters and express the movement invariants, i.e. the trajectory segmentation into units of action and the two-thirds power law. The central vs peripheral origin of such constraints involved in the motor system is discussed.

  • 7. Arvidsson, Inger
    et al.
    Hansson, Gert-Åke
    Mathiassen, Svend Erik
    University of Gävle, Belastningsskadecentrum.
    Skerfving, Staffan
    "Gamnacke" och nackbesvär vid datorarbete: finns det något samband?2005In: Svenska Läkaresällskapets Riksstämma, 2005Conference paper (Other academic)
  • 8.
    Barnekow-Bergkvist, Margareta
    et al.
    University of Gävle, Belastningsskadecentrum.
    Aasa, Ulrika
    University of Gävle, Belastningsskadecentrum.
    Ängquist, K-A
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Prediction of development of fatigue during a simulated ambulance work task from physical performance tests2004In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847, Vol. 47, no 11, 1238-1250 p.Article in journal (Refereed)
    Abstract [en]

    The aims of this study were (1) to identify which physical performance tests could best explain the development of fatigue during a simulated ambulance work task, (2) to investigate the effect of height and weight and (3) to investigate in what respects these findings differ between female and male ambulance personnel. Forty-eight male and 17 female ambulance personnel completed a test battery assessing cardio-respiratory capacity, muscular strength and endurance, and co-ordination. The subjects also completed a simulated ambulance work task -- carrying a loaded stretcher. The work task was evaluated by development of fatigue. Univariate and multiple regression analyses were used to investigate to what extent the tests in the test battery were able to explain the variance of developed fatigue. The explained variance was higher for female than for male ambulance personnel (time > 70% of HRpeak: R2 = 0.75 vs 0.10, accumulated lactate: R2 = 0.62 vs 0.42, perceived exertion: R2 = 0.75 vs 0.10). Significant predictors in the models were VO2max, isometric back endurance, one-leg rising, isokinetic knee flexion and shoulder extension strength. Height, but not weight, could further explain the variance. The high physical strain during carrying the loaded stretcher implies the importance of investigating whether improved performance, matching the occupational demands, could decrease the development of fatigue during strenuous tasks.

  • 9. Bechtereva, N P
    et al.
    Korotkov, A D
    University of Gävle, Belastningsskadecentrum.
    Pakhomov, S V
    Roudas, M S
    Starchenko, M G
    Medvedev, S V
    PET study of brain maintenance of verbal creative activity.2004In: International Journal of Psychophysiology, ISSN 0167-8760, E-ISSN 1872-7697, Vol. 53, no 1, 11-20 p.Article in journal (Refereed)
    Abstract [en]

    This paper deals with the investigation of the brain organization of verbal creativity. Psychological tasks were designed in accordance with two main strategies used by volunteers in solving creative tasks. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) when performing two types of creative tasks in two groups of subjects, each type of the task organizing the creativity process in its own way. Brain correlates of creativity were revealed in the left parieto-temporal regions (Brodmann areas 39 and 40).

  • 10.
    Bergenheim, Mikael
    et al.
    University of Gävle, Belastningsskadecentrum.
    Ribot-Ciscar, E
    Roll, J-P
    Thunberg, Johan
    University of Gävle, Belastningsskadecentrum.
    Spontaneous bursting neuronal discharges recorded from peripheral nerve in human: injury discharges or not?2004In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 359, no 1-2, 1-4 p.Article in journal (Refereed)
    Abstract [en]

    This paper deals with a spontaneous, bursting neuronal activity which can not be altered by any stimulation in the periphery or voluntary actions or by cognitive tasks. An initial description of such units led to the conclusion that this activity was generated ectopically at the site of a previous or present impalement of a nerve fibre. The aim of the current study was to record a larger number of these units by using microneurography, in order to characterise their firing properties and particularly, see if any subtypes of units could be identified. In conclusion, this paper suggests that some of these discharges could be related to an injury of the nerve fibre, however most of them could not. Some hypothesis regarding the nature of these bursting activities are suggested.

  • 11. Bergfors, M
    et al.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Kalezic, Nebojsa
    University of Gävle, Belastningsskadecentrum.
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Eriksson, J W
    Short-term effects of repetitive arm work and dynamic exercise on glucose metabolism and insulin sensitivity.2005In: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 183, no 4, 345-356 p.Article in journal (Refereed)
    Abstract [en]

    Aim: To detennine whether repetitive ann work, with a large component of static muscle contraction alters glucose metabolism and insulin sensitivity.

    Methad: Euglycemic clamps (2h) were started in ten healthy individuals 15 minutes after 37 minute periods of: 1) repetitive ann work in a simulated occupational setting; 2) dynamic concentric exercise on a cycle ergometer at 60% OfVO2 max and 3) a resting regime as a control. During the experimental periods, blood samples were collected, blood pressure was measured repeatedly and electrocardiogram (ECG) wasrecorded continuously. During the clamps, euglycemia was maintained at 5 mmo1/l and insulin was infused at 56 mU/m2/min for 120 min.

    Results: The insulin-mediated glucose disposal rate (M-value) for the steady state period (60- 120 min) of the clamp, tended to be lower following ann work than for both cycling and resting regimes. When dividing the steady state period into 20-minute intervals, the insulin sensitivity index, (ISI) was significantly lower for ann work compared with the resting control situation between 60-80 minutes (p=0.04) and 80-100 minutes (p=0.01) respectively.

    Catecholamines increased significantly for ann work and cycling compared with resting regime. .Data from heart rate variability (HRV) me asurements indicated significant sympathetic activation during repetitive ann work test.

    Canelusian: The results indicate that repetitive ann work might acutely promote insulin resistance, whereas no such effect on insulin resistance was produced by dynamic concentric exercise.

  • 12.
    Bergström, Sten Sture
    University of Gävle, Belastningsskadecentrum.
    The AMBEGUJAS phenomenon and colour constancy2004In: Perception, ISSN 0301-0066, E-ISSN 1468-4233, Vol. 33, no 7, 831-835 p.Article in journal (Refereed)
    Abstract [en]

    The AMBEGUJAS phenomenon is a reversible flat figure that is spontaneously shifting between two apparent 3-0 shapes-'tile' and 'roor. 2-0 perceptions have very rarely been reported. Tied to the shifts between the tile and roof shapes are remarkable changes of perceived colour. In our example, the tile appears to have orange (top half) and blue-green (bottom half) surface colours in white light. The roof appears grey but in an orange illumination and with a blue -green shadow. This phenomenon appears whether a grey display is presented in two coloured illuminations, or a chromatic display with two surface colours (orange and blue -green) is presented in white light. In the coloured illuminations the tile is an example of non-constancy, since its colours are non-veridical colour perceptions. The centre stripe of the display appears to have the same orange and blue -green colours as the lateral stripes but in a shadow. This seems like a colour constancy in a non-constancy situation. An alternative to the classical definition of colour constancy is discussed.

  • 13.
    Björklund, Martin
    University of Gävle, Belastningsskadecentrum.
    Effects of Repetitive Work on Proprioception and of Stretching on Sensory Mechanisms: Implications for Work-related Neuromuscular Disorders2004Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Repetitive low-intensïty work constitutes an important risk factor for Chronic Wark Related Neuromuscular Disorders (CWRND)· Derangemcnt of motor control, provoked by loaded or fati ued muscles, has been suggested as one of the underlying mechanisms behind these disorders. Faàgue-induced reduetion of proprioceptive acuity may be one of the factors accounting for the deranged motor eontrol. In contrast to high-intensity work, little ïs known about the effect of repetitive low-intensity work on proprioceptive acuity. Muscle stretching has becn proposed as a rocedure that can prevcnt, alleviate and/or treat CWRND· Before the importance of stretching can be adequately assessed for this purpose, a better understanding of the effects of stretching and the pathophysiological mechanisms behind thc work-related disorders are needed. The aims of the thesis were (i) to investigate the impact of repetitive low-intensity work exposure on proprioception and (ü) to examine effects of muscle stretching (especially sensory effects and effects on muscle nociception) and to relate its application to the prevention, alleviation and/or treatment of CWRND A simulated occupational setting was used to test the effects of low-intensity repetitive work on the shoulder proprioception in healthy subjècts. The effect of working time on the retention of subjective fatigue and their relation to changes in proprioception, and the immediate effect of stretching on shoulder proprioception were investìgated. A new method to test the stretchability of the rectus femoris muscle was investigated for reliability and validity and used to assess the effects of a 2-week stretching regimen on range of motion and an subjecàve stretch sensation. Finally, the interactions between innocuous musclc stretch and naciceptive chemical stimulaàon on discharge behavior of nociceptive dorsal horn neurons in the feline spinal cord were explored. The main findings wcre as follows: 1) The repctiàve low-intensity work to fatigue diminished the shoulder proprioceptian; the working time as well as the retention of subjective fatigue were partly related to the extent of changed praprioception: 2) There was no effect of acute muscle stretching on the proprioccpàon. 3) The ncw method for tesàng musele stretchability proved valid and reliable. A two-week stretching regimen inereased the tolerance to stretch torque, but the range of moàon remained unchanged. 4) Half of the nociceptive dorsal horn neurons that responded to close arterial injections of bradykinin were modulated by muscle stretching applied directly aftér thc injections. h thcsis of an involvement of sensory Altogether, the results give credence to the hypo information distonion due to repeàtive low.intensity work exposure in the development of CWRND· Increased toleranee to stretch torque may be an imponant mechanism i explaining improvements followin stretch treatment. The spinal interactions between innocuaus stretch and nociceptive muscle af erent inputs indicate a possible mrchanism involved in stretching-induced pain alleviaàon.

  • 14.
    Björklund, Martin
    et al.
    University of Gävle, Belastningsskadecentrum.
    Crenshaw, Albert
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Position sense acuity is diminished following repetitive low-intensity work to fatigue in a simulated occupational setting. A critical comment2003In: European Journal of Applied Physiology and Occupational Physiology, ISSN 0301-5548, E-ISSN 1432-1025, Vol. 88, no 4-5, 485-486 p.Article in journal (Refereed)
  • 15.
    Björklund, Martin
    et al.
    University of Gävle, Belastningsskadecentrum.
    Radovanovic, Sasa
    University of Gävle, Belastningsskadecentrum.
    Ljubisavljevic, Milos
    University of Gävle, Belastningsskadecentrum.
    Windhorst, Uwe
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Muscle stretch-induced modulation of noxiously activated dorsal horn neurons of feline spinal cord.2004In: Neuroscience research, ISSN 0168-0102, E-ISSN 1872-8111, Vol. 48, no 2, 175-184 p.Article in journal (Refereed)
    Abstract [en]

    The present work was designed to check for the possibility of interactions between mechanical innocuous and chemically induced noxious muscle afferent inputs on discharge behavior of nociceptive superficial dorsal horn neurons (SDHNs) of the spinal cord in decerebrated cats. The innocuous and noxious stimuli were applied separately and in combination, so that the effects of the innocuous stimulus on nociceptive processing could be evaluated. The innocuous stimulus consisted of ramp-and-hold stretches of the gastrocnemius muscles, whereas the noxious stimulus consisted of i.a. injections of bradykinin (BK; 0.5-1 ml, 50 microg/ml) into the arterial circulation of same muscles. Only neurons up to approximately 1mm depth and those that responded to noxious pinch of the gastrocnemius muscles were selected for further analysis. The activity of 16 dorsal horn neurons was recorded extracellularly with high-impedance glass microelectrodes, out of which seven responded to stretch, while 12 neurons responded to bradykinin injections. The bradykinin injections induced three types of responses: excitatory, inhibitory and mixed. The majority of the neurons that showed excitatory and mixed responses to bradykinin were also influenced by stretches applied directly after the bradykinin injection. In these neurons, the stretch usually counteracted the bradykinin-induced response, i.e. shortening and reducing bradykinin-induced excitation and re-exciting the cells after bradykinin-induced inhibition. The mechanism of the stretch modulation is proposed to reside in a segmental spinal control of the nociceptive transmission.

  • 16.
    Crenshaw, Albert G
    et al.
    University of Gävle, Belastningsskadecentrum.
    Heiden, Marina
    University of Gävle, Belastningsskadecentrum.
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Reduced muscular oxygenation during computer mouse use with time pressure and precision demands2004In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 35, no 5, S221-S222 p.Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Monitoring oxidative metabolic states may provide information on the mechanism behind computer use related musculoskeletal disorders. PURPOSE: To compare tissue oxygen saturation (Sat-O2) profiles in the forearm extensor carpi radialis (ECR) during computer mouse use with and without time pressure and precision demands. METHODS: Twenty-four healthy, right-handed subjects (12 females, 12 males; age 19-28 years) participated in the study. Subjects performed a 45-min mouse operated computer task on two occasions, separated by 3-5 days. The task consisted of painting squares that were presented on the screen. On one occasion, time pressure and precision demands were imposed by limiting the time available for painting a square and introducing a scoring system based on precision of painting (STRESS). On the other occasion, no such restraints were added (NON-STRESS). The order of the two task versions was randomized. During the task, Sat-O2 in the right ECR muscle was measured by near-infrared spectroscopy – NIRS (Inspectra, Hutchinson Technology). In addition, subjective ratings of tenseness and strain, and painting performance measures were recorded. RESULTS: A repeated measures ANOVA revealed a significant decline in Sat-O2 during the STRESS condition (p < 0.05), but no change for the NON-STRESS condition. A gender difference was apparent as females exhibited an overall lower Sat-O2 than males (p < 0.05); however, no interaction was found. Subjectsメ ratings of tenseness and strain were significantly higher during the STRESS as compared to the NON-STRESS condition (p < 0.001). These data were paralleled by work pace (i.e. squares painted during STRESS = 119; NON-STRESS = 84, p < 0.001). Furthermore, accuracy of painting was greater for the STRESS as compared to the NON-STRESS condition (p < 0.01), i.e., number of times outside the square, STRESS = 2, NON-STRESS = 4. No gender differences in subjective ratings or performance variables were detected. CONCLUSIONS: Our finding of a change in local metabolic states under stressful conditions may shed light on the mechanism behind computer mouse related forearm muscular disorders. Furthermore, that females demonstrate a lower ECR Sat-O2 could give precedence to their higher incidence of disorders than males

  • 17.
    Crenshaw, Albert G.
    et al.
    University of Gävle, Belastningsskadecentrum.
    Heiden, Marina
    University of Gävle, Belastningsskadecentrum.
    Svedmark, Åsa
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Reliability Of Oxygen Saturation Of Forearm Extensor And Trapezius Muscles Of Males And Females (Poster)2005Conference paper (Refereed)
  • 18.
    Crenshaw, Albert G
    et al.
    University of Gävle, Belastningsskadecentrum.
    Jensen, B R
    Near infrared spectroscopy for measuring muscle oxygenation2005In: Proceedings of the International Federation for Medical and Biological Engineering. 13th Nordic Baltic Conference Biomedical Engineering and Medical Physics. 13 NBC 2005, 2005Conference paper (Refereed)
    Abstract [en]

    The advent of near infrared spectroscopy (NIRS) as a tool for monitoring muscle oxygenation has allowed for important physiological data in sports training and rehabilitation. Commercial methods are generally user-friendly and the technique is non- invasive. By projecting a light beam in to the muscle concentrations of haemoglobin/myoglobin (with and without oxygen) in the vascular bed consisting of small arterioles, capillaries and venules can be determined. Despite its appeal methodological improvements to account for varying muscle depths, and to distinguish between arteriolar and venular contributions separatelyare desired.

  • 19.
    Daerga, Laila
    et al.
    University of Gävle, Belastningsskadecentrum.
    Edin-Liljegren, Anette
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Work-related musculoskeletal pain among reindeer herding Sami in Sweden: a pilot study on causes and prevention2004In: International Journal of Circumpolar Health, ISSN 1239-9736, Vol. 63 Suppl 2, 343-348 p.Article in journal (Refereed)
    Abstract [en]

    Objective. To investigate the prevalence and to identify causes of musculoskeletal pain (MSP) among reindeer herding Sami, and to evaluate the impact on the MSP symptoms elicited by an intervention-pre- vention programme (lP programme). Study Design. A prospective cohort study in which alterations in MSP symptoms were documented over a two-year period. Methods. Data were collected from 51 rein- deer herders (26 men, 25 w omen) before and af ter a two-year lP programme. Information on MSP cha- racteristics (affected body regions, pain duration and pain intensity) and exposure to a number of phy- sical and psychosocial risk factors were collected as part of comprehensive health examinations. Cli- nical examinations and interviews complemented self-reported data collected through questionnaires. Results. MSP symptoms were prevalent, both among w omen and men. High exposure to physical risk factors, to a large extent related to extensive use of snowmobiles and motorcycles, was the main cau- se of MSP among men, while psychosocial risk factors were suggested to be more important among wo- men. About one-third of the reindeer herders reported fewer MSP symptoms as a resull of the lP programme. Conclusions. This pilot study suggests that it is possible to reduce the number and the se- verity of the MSP symptoms among reindeer herders by implementing suitably tailored intervention- prevention measures.

  • 20. Daerga, Laila
    et al.
    Hassler, Sven
    Edin-Liljegren, Anette
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Arbetsrelaterade dödsolyckor och belastningsskador bland renskötande samer2005In: Glesbygdsmedicinska föreningens årsmöte, Arvidsjaur, 2005Conference paper (Other (popular science, discussion, etc.))
  • 21.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Effects of physical work exposure on proprioception2003In: Chronic work-related myalgia: neuromuscular mechanisms behind work-related chronic muscle pain syndromes, Gävle: Gävle University Press , 2003, 175-183 p.Chapter in book (Other academic)
  • 22.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Proprioception in chronic neck pain patients2004In: International Congress on Chronic Pain and Dysfunction after Whiplash and other Traumatic Neck Injuries, 2004, 7-10 p.Conference paper (Refereed)
  • 23.
    Djupsjöbacka, Mats
    et al.
    University of Gävle, Belastningsskadecentrum.
    Domkin, Dmitry
    University of Gävle, Belastningsskadecentrum.
    Correlation analysis of proprioceptive acuity in ipsilateral position-matching and velocity-discrimination2005In: Somatosensory & motor research, ISSN 0899-0220, E-ISSN 1369-1651, Vol. 22, no 1-2, 85-93 p.Article in journal (Refereed)
    Abstract [en]

    In order to plan and control movements the central nervous system (CNS) needs to continuously keep track of the state of the musculoskeletal system. Therefore the CNS constantly uses sensory input from mechanoreceptors in muscles, joints and skin to update information about body configuration on different levels of the CNS. On the conscious level, such representations constitute proprioception. Different tests for assessment of proprioceptive acuity have been described. However, it is unclear if the proprioceptive acuity measurements in these tests correlate within subjects. By using both uni- and multivariate analysis we compared proprioceptive acuity in different variants of ipsilateral active and passive limb position-matching and ipsilateral passive limb movement velocity-discrimination in a group of healthy subjects. The analysis of the position-matching data revealed a higher acuity of matching for active movements in comparison to passive ones. The acuity of matching was negatively correlated to movement extent. There was a lack of correlation between proprioceptive acuity measurements in position-matching and velocity-discrimination.

  • 24.
    Djupsjöbacka, Mats
    et al.
    University of Gävle, Belastningsskadecentrum.
    Gellerstedt, Sten
    Stenberg, Leif
    University of Gävle, Belastningsskadecentrum.
    Muskelvärk?: Långvarig muskelsmärta vid arbete - risker, uppkomst och åtgärder2004Book (Other (popular science, discussion, etc.))
  • 25.
    Djupsjöbacka, Mats
    et al.
    University of Gävle, Belastningsskadecentrum.
    Johansson, Bengt HUniversity of Gävle, Belastningsskadecentrum.Mathiassen, Svend ErikUniversity of Gävle, Belastningsskadecentrum.Sjölander, PerUniversity of Gävle, Belastningsskadecentrum.
    International Congress on Chronic Pain and Dysfunction after Whiplash and other Traumatic Neck Injuries: October 28-29, 2004.2004Conference proceedings (editor) (Other (popular science, discussion, etc.))
  • 26.
    Domkin, Dmitry
    University of Gävle, Belastningsskadecentrum.
    Perception and control of upper limb movement: Insights gained by analysis of sensory and motor variability2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Clinical research has presented evidence that chronic neck-shoulder pain is associated with impairments ofproprioception (perception oflimb position and movement without vision and touch) and motor control. Thus, assessment ofproprioceptive and motor function of the upper limb may be powerful tools both for research and clinical practice. However, insufficient knowledge of certain features of human sensorimotor control haropers both development and interpretation of results of clinically relevant tests. For example, evidence is lacking which proprioception submodalities (position and movement sense) are reflected in common tests of shoulder proprioception. With respect to testing of upper limb motor function, a better understanding of the control of goal directed arm movements would be needed.

    The overall purpose of the thesis was to gain further insights into the sensorimotor control of the upper limb in healthy subjects, with implications for clinical testing and ergonomics. The main aims were: ( 1) to study relationships of outcomes of different psychophysical tests for assessment ofproprioceptive acuity in the shoulder joint and (2) to study control strategies in repetitive bimanual pointing tasks by analysis of the structure ofjoint angle variability.

    Proprioceptive acuity was assessed in several variants of ipsilateral position- matching and velocity-discrimination by testing subjects' ability to repeat a memorized arm location and to discriminate between two different velocities of arm movement, respectively. Sensory discrimination thresholds were represented by Yariable Errors (YEs) for position-matching and by Just Noticeable Differences (JNDs) for velocity-discrimination. The pattem of correlations of the YEs and JNDs was analyzed by Principal Component Analysis. The main finding was that two uncorrelated mechanisms based either on perception of position or movement might underlie perception of limb location in ipsilateral position-matching. This depended on the extent of arm movement and on association of the memorized arm location with an active location-focused searching task. The results provided important information for interpretation of common tests of shoulder proprioception with implications for design of novel tests allowing for specific proprioception submodalities to be addressed.

    Control strategies in bimanual pointing in 2D and 3D space were studied within the Uncontrolled Manifold (U CM) hypothesis. The structure of joint angle variance was computed wjth respect to the vectorial distance between the endpoints of the arms and with respect to the endpoint coordinates of each arm separately (selected task variables). Joint angle variability was decomposed in variance affecting (YUN) and not affecting (Y COMP) a task variable. The U CM hypothesis predicts that the central nervous system stabilizes a task variable by minimizing Y UN, while allowing Y COMP to be high. Thus, the ratio of these variance components quantifies the degree of control of the task variable. The results showed that the variance in joint space was structured according to the predictions of the U CM hypothesis. It was also shown that the arms were united into one synergy to significantly larger degree than joints within each arm were united into single-arm synergies. It was concluded that the U CM method might quantify components ofmotor variability during repetitive motor tasks, which are not detectable by conventional performance measures.

  • 27.
    Domkin, Dmitry
    et al.
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Outcomes of ipsilateral position matching and velocity discrimination are uncorrelated2003In: Sensorimotor Coordination, behavioural modes and neural mechanisms, Fraser Island, Australia, 2003Conference paper (Refereed)
    Abstract [en]

    The central nervous system processes sensory input from proprioceptors to form a state estimate of body configuration, which represents proprioception on theconscious level. Proprioception can be divided in two submodalities: sense of movement and sense of position. It is unclear whether tests, involving psychophysical methods and assessing proprioceptive acuity, can separate between perception of movement and position and thus, measure specific proprioception submodalities. In order to investigate if position matching and velocity discrimination tests can separate perception of position and perception of movement, correlations between outcomes of these tests were analyzed. Sixteen young healthy right-handed and gender balanced subjects performed movements in the right glenohumeral joint in all tests. In the ipsilateral position matching test subjects replicated an arm location, achieved in a criterion movement. Movements were performed from positions Q, 4Q and 80- degrees to target positions 16, 32, 48 and 64 degrees with respect to the body sagittal plane. Four conditions, different in terms of movement mode to the target position during criterion and replication movement, were used: passive-active, passive-passive, active-active, semipassive-semipassive. In the latter condition subjects slightly resisted the passive movement. In the ipsilateral velocity discrimination test subjects assessed if a latter comparison arm movement was faster or slower than a previous criterion movement. Criterion movements were performed at velocities of 3Q and 5Q deg/s. T wo conditions were used: passive-passive and semipassive-semipassive. Variable errors (VE) andjust noticeable differences (JND) were measures of proprioceptive acuity in the position matching and velocity discrimination, respectively. Hierarchical cluster analysis (H CA) and principal component analysis (PCA) were applied to study correlations between outcomes in conditions of both tests. In the H CA solution, the position matchi ng and velocity discrimination conditions were located in clusters on opposite poles of the cluster structure. The PCA results were interpreted for six significant components. The position matching and velocity discrimination conditions loaded mainly on components one to five and on component six, respectively. Both the H CA and the PCA separated all test conditions in t wo groups: one contained the position matching and another the velocity discrimination conditions. There were no clear differences between conditions within each group. The study showed that the outcomes VE and JND of the position matching and velocity discrimination, respectively, are mainly uncorrelated. This implies that these tests likely measure different proprioceptive perceptual components or their different combinations. The position matching and velocity discrimination tests could in general separate between perception of position and movement, although no direct evidence was obtained for ex act match of each test with specific proprioception submodality. Much clearer separation of the measured outcomes could be achieved in subjects, heterogeneous with respect to proprioceptive acuity, i.e. with larger variability of performance.

  • 28.
    Domkin, Dmitry
    et al.
    University of Gävle, Belastningsskadecentrum.
    Laczko, Jozsef
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Jaric, Slobodan
    Latash, Mark L
    Joint angle variability in 3D bimanual pointing: uncontrolled manifold analysis.2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 163, no 1, 44-57 p.Article in journal (Refereed)
    Abstract [en]

    The structure of joint angle variability and its changes with practice were investigated using the uncontrolled manifold (UCM) computational approach. Subjects performed fast and accurate bimanual pointing movements in 3D space, trying to match the tip of a pointer, held in the right hand, with the tip of one of three different targets, held in the left hand during a pre-test, several practice sessions and a post-test. The prediction of the UCM approach about the structuring of joint angle variance for selective stabilization of important task variables was tested with respect to selective stabilization of time series of the vectorial distance between the pointer and aimed target tips (bimanual control hypothesis) and with respect to selective stabilization of the endpoint trajectory of each arm (unimanual control hypothesis). The components of the total joint angle variance not affecting (V(COMP)) and affecting (V(UN)) the value of a selected task variable were computed for each 10% of the normalized movement time. The ratio of these two components R(V)=V(COMP)/V(UN) served as a quantitative index of selective stabilization. Both the bimanual and unimanual control hypotheses were supported, however the R(V) values for the bimanual hypothesis were significantly higher than those for the unimanual hypothesis applied to the left and right arm both prior to and after practice. This suggests that the CNS stabilizes the relative trajectory of one endpoint with respect to the other more than it stabilizes the trajectories of each of the endpoints in the external space. Practice-associated improvement in both movement speed and accuracy was accompanied by counter-intuitive lack of changes in R(V). Both V(COMP) and V(UN) variance components decreased such that their ratio remained constant prior to and after practice. We conclude that the UCM approach offers a unique and under-explored opportunity to track changes in the organization of multi-effector systems with practice and allows quantitative assessment of the degree of stabilization of selected performance variables.

  • 29.
    Domkin, Dmitry
    et al.
    University of Gävle, Belastningsskadecentrum.
    Laczko, Jozsef
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Jaric, Slobodan
    Latash, Mark L
    Joint angle variability in 3D bimanual pointing: uncontrolled manifold analysis2004In: Motor Control 2004, 2004Conference paper (Other (popular science, discussion, etc.))
  • 30.
    Domkin, Dmitry
    et al.
    University of Gävle, Belastningsskadecentrum.
    Laczko, Jozsef
    Department of Biomechanics, Semmelweis University, Budapest, Hungary.
    Jaric, Slobodan
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Latash, Mark L.
    Department of Kinesiology, The Pennsylvanaia State University, University Park, USA.
    Structure of joint variability in bimanual pointing tasks2002In: Experimental Brain Research, Vol. 143, 11-23 p.Article in journal (Refereed)
    Abstract [en]

    Changes in the structure of motor variability during practicing a bimanual pointing task were investigated using the framework of the uncontrolled manifold (UCM) hypothesis. The subjects performed fast and accurate planar movements with both arms, one moving the pointer and the other moving the target. The UCM hypothesis predicts that joint kinematic variability will be structured to selectively stabilize important task variables. This prediction was tested with respect to selective stabilization of the trajectory of the endpoint of each arm (unimanual control hypotheses) and with respect to selective stabilization of the timecourse of the vectorial distance between the target and the pointer tip (bimanual control hypothesis). Components of joint position variance not affecting and affecting a mean value of a selected variable were computed at each 10% of normalized movement time. The ratio of these two components (RV) served as a quantitative index of selective stabilization. Both unimanual control hypotheses and the bimanual control hypothesis were supported both prior to and after practice. However, the RV values for the bimanual control hypothesis were significantly higher than for either of the unimanual control hypothesis, suggesting that the bimanual synergy was not simply a simultaneous execution of two unimanual synergies. After practice, an improvement in both movement speed and accuracy was accompanied by counterintuitive changes in the structure of kinematic variability. Components of joint position variance affecting and not affecting a mean value of a selected variable decreased, but there was a significantly larger drop in the latter when applied on each of the three selected task variables corresponding to the three control hypotheses. We conclude that the UCM hypothesis allows quantitative assessment of the degree of stabilization of selected performance variables and provides information on changes in the structure of a multijoint synergy that may not be reflected in its overall performance. Keywords. Coordination - Variability - Voluntary movement - Bimanual - Human

  • 31. Edin-Liljegren, Anette
    et al.
    Hassler, Sven
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Daerga, Laila
    University of Gävle, Belastningsskadecentrum.
    Risk factors for cardiovascular diseases among Swedish Sami: a controlled cohort study2004In: International Journal of Circumpolar Health, ISSN 1239-9736, Vol. 63 Suppl 2, 292-297 p.Article in journal (Refereed)
    Abstract [en]

    Objective. To investigate the occurrence of clinical, psychosocial and behavioural risk factors for cardiovascular di seases (C VD) among reindeer herding (RS) and non-reindeer herding Sami (NRS). Study Design. A retrospective cohort study, comparing risk factors behind C VD between Sami and non-Sami, RS and NRS, and Sami men and w omen. Methods. A cohort of 611 Swedish Sami (276 men and 335 w omen) was constructed from national population registers. A twice as large control co- hort of non-Sami was created, matched by age, gender and area of residence. Information on risk factors was obtained from a database containing clinical and psychosocial-behavioural data from a regional C VD preventive programme for the period 1990-2001. Results. The Sami and thenon-Sa- mi showed similar risk factor patterns. The main differences were related to working conditions and lifestyle factors of the RS. The RS men had lower blood pressure, were more physically active and had higher job demand and decision latitude. The RS w omen showed more negative scores on the in- dices of the job strain model. Conclusions. Previously reported differences in C VD mortality between Sami and non-Sami, and Sami men and w omen, can only partly be explained by different exposure to the psychosocial and behaviour risk factors investigated in this study.

  • 32. Eriksson, A
    et al.
    Kadi, F
    Thornell, Lars-Eric
    University of Gävle, Belastningsskadecentrum.
    Mechanisms Related to Muscle Fiber Hypertrophy in Undoped and Doped Power Lifters2004In: APS Intersociety Meeting, The Integrative Biology of Exercise: Austin Texas, October 6-9, 2004Conference paper (Other (popular science, discussion, etc.))
  • 33.
    Eriksson, Anders
    et al.
    University of Gävle, Belastningsskadecentrum.
    Kadi, Fawzi
    Malm, Christer
    Thornell, Lars-Eric
    University of Gävle, Belastningsskadecentrum.
    Skeletal muscle morphology in power-lifters with and without anabolic steroids.2005In: Histochemistry and Cell Biology, ISSN 0948-6143, E-ISSN 1432-119X, Vol. 124, no 2, 167-175 p.Article in journal (Refereed)
    Abstract [en]

    The morphological appearance of the vastus lateralis (VL) muscle from high-level power-lifters on long-term anabolic steroid supplementation (PAS) and power-lifters never taking anabolic steroids (P) was compared. The effects of long- and short-term supplementation were compared. Enzyme-immunohistochemical investigations were performed to assess muscle fiber type composition, fiber area, number of myonuclei per fiber, internal myonuclei, myonuclear domains and proportion of satellite cells. The PAS group had larger type I, IIA, IIAB and IIC fiber areas (p<0.05). The number of myonuclei/fiber and the proportion of central nuclei were significantly higher in the PAS group (p<0.05). Similar results were seen in the trapezius muscle (T) but additionally, in T the proportion of fibers expressing developmental myosin isoforms was higher in the PAS group compared to the P group. Further, in VL, the PAS group had significantly larger nuclear domains in fibers containing > or = 5 myonuclei. The results of AS on VL morphology in this study were similar to previously reported short-term effects of AS on VL. The initial effects from AS appear to be maintained for several years

  • 34.
    Eriksson, Per-Olof
    University of Gävle, Belastningsskadecentrum.
    Can neck injury disturb eating behaviour2004In: International Congress on Chronic Pain and Dysfunction after Whiplash and other Traumatic Neck Injuries, 2004, 32-34 p.Conference paper (Refereed)
  • 35.
    Eriksson, Per-Olof
    et al.
    University of Gävle, Belastningsskadecentrum.
    Zafar, Hamayun
    Backén, Mattias
    Association between jaw function and postural control in neck-related musculoskelal disorders2004In: Proceedings of the 5th International Scientific Conference on Prevention of Work-Related Musculoskeletal Disorders (PREMUS): Zurich, Switzerland, July 11-15, 2004Conference paper (Other academic)
  • 36.
    Eriksson, Per-Olof
    et al.
    University of Gävle, Belastningsskadecentrum.
    Zafar, Hamayun
    Häggman-Henrikson, Birgitta
    Deranged jaw-neck motor control in whiplash-associated disorders2004In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 112, no 1, 25-32 p.Article in journal (Refereed)
    Abstract [en]

    Recent findings of simultaneous and well coordinated head-neck movements during single as well as rhythmic jaw opening-closing tasks has led to the conclusion that 'functional jaw movements' are the result of activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital and cervical spine joints. It can therefore be assumed that disease or injury to any of these joint systems would disturb natural jaw function. To test this hypothesis, amplitudes, temporal coordination, and spatiotemporal consistency of concomitant mandibular and head-neck movements during single maximal jaw opening-closing tasks were analysed in 25 individuals suffering from whiplash-associated disorders (WAD) using optoelectronic movement recording technique. In addition, the relative durations for which the head position was equal to, leading ahead of, or lagging behind the mandibular position during the entire jaw opening-closing cycle were determined. Compared with healthy individuals, the WAD group showed smaller amplitudes, and changed temporal coordination between mandibular and head-neck movements. No divergence from healthy individuals was found for the spatiotemporal consistency or for the analysis during the entire jaw opening-closing cycle. These findings in the WAD group of a 'faulty', but yet consistent, jaw-neck behavior may reflect a basic importance of linked control of the jaw and neck sensory-motor systems. In conclusion, the present results suggest that neck injury is associated with deranged control of mandibular and head-neck movements during jaw opening-closing tasks, and therefore might compromise natural jaw function.

  • 37.
    Flodgren, Gerd
    et al.
    University of Gävle, Belastningsskadecentrum.
    Crenshaw, Albert
    University of Gävle, Belastningsskadecentrum.
    Alfredson, Håkan
    Fahlström, Martin
    Hellström, Fredrik
    University of Gävle, Belastningsskadecentrum.
    Bronemo, Lars
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Interstitial PGE2 and glutamate levels in the trapezius muscle of females - determined by microdialysis (poster)2004In: Medicine & Science in Sports & Exercise: May 2004 - Volume 36 - Issue 5 - p S332, 2004Conference paper (Other (popular science, discussion, etc.))
  • 38.
    Flodgren, Gerd M
    et al.
    University of Gävle, Belastningsskadecentrum.
    Crenshaw, Albert G
    University of Gävle, Belastningsskadecentrum.
    Alfredson, Håkan
    Fahlström, Martin
    Hellström, Fredrik B
    University of Gävle, Belastningsskadecentrum.
    Bronemo, Lars
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Glutamate and prostaglandin E2 in the trapezius muscle of female subjects with chronic muscle pain and controls determined by microdialysis.2005In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 9, no 5, 511-515 p.Article in journal (Refereed)
    Abstract [en]

    Much is still unknown concerning the mechanisms underlying the development of chronic muscle pain. The presence and magnitude of inflammatory substances and neurotransmitters in chronic painful conditions is not clear. The aims of the present study were to determine, with the use of microdialysis, the interstitial concentrations and the equilibration times for PGE(2) and glutamate in the trapezius muscles of nine female subjects with chronic muscle pain, and nine pain-free age-matched controls. A microdialysis probe was implanted in the upper part of the trapezius muscle and perfused with Ringer-acetate solution at a flow rate of 0.3 muL/min. Samples were obtained every 30 min, during a 4-h rest period. At equilibration, the mean concentrations (+/-SE) of PGE(2) were 0.71 (+/-0.11) ng/mL for the pain-group and 0.97 (+/-0.35) ng/mL for the controls. For glutamate the mean concentrations for the pain-group were 66.3 (+/-13.3) mumol/L and 60.6 (+/-22.9) mumol/L for the controls. For the pain group and the control group, respectively, equilibration for PGE(2) was reached at 180 and 150 min, and for glutamate at 150 and 120 min. The present study showed no differences between groups in the concentrations of PGE(2) and glutamate in the trapezius muscle. Further, it revealed that when using the slow-flow method, a period of at least 2.0-2.5 h is needed, after probe insertion, to reach steady state for glutamate and PGE(2).

  • 39. Garkavenko, V V
    et al.
    Gorkovenko, A V
    Man'kovskaya, E P
    Shevko, A N
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Kostyukov, A I
    University of Gävle, Belastningsskadecentrum.
    Change in the Power of EEG Activity in the a Range in Response to Tonic Nociceptive Stimulation of the Distal Joint of the Little Finger2005In: Human Physiology, ISSN 0362-1197, E-ISSN 1608-3164, Vol. 31, no 2, 188-94 p.Article in journal (Refereed)
    Abstract [en]

    Examination of 12 healthy volunteers aged 20–56 years was performed to study the EEG changes caused by a tonic squeeze of the distal joint of the little finger of the left and then the right hand. This stimulation caused painful sensations of different intensity (pain on the right was stronger). Spectral power was measured in the alfa1 (8–10.5 Hz) and alfa2 ranges (10.5–13 Hz) under different conditions. Weak pain led to an increase in the power of the alfa1 and alfa2 ranges in the occipital regions. With strong pain, the power of alfa1 waves increased bilaterally in the posterior regions (O1,O2,T6), as well as in the left frontal region (F3,F7). The powers of the alfa1and alfa2 ranges substantially increased relative to the background level after the strong nociceptive stimulation ceased. This finding testified to a latent and inertial character of its effect on the wave parameters.

  • 40. Grönqvist, J
    et al.
    Häggman-Henrikson, B
    Eriksson, Per-Olov
    University of Gävle, Belastningsskadecentrum.
    Eating behavior in Whiplash Associated Disorders2004In: Odontologisk Riksstämma: Älvsjö, 2004Conference paper (Other (popular science, discussion, etc.))
  • 41. Hassler, Sven
    et al.
    Johansson, Robert
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Grönberg, Henrik
    Damber, Lena
    Causes of death in the Sami population of Sweden, 1961-2000.2005In: International Journal of Epidemiology, ISSN 0300-5771, E-ISSN 1464-3685, Vol. 34, no 3, 623-629 p.Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Indigenous people often have a pattern of mortality that is disadvantageous in comparison with the general population. The knowledge on causes of death among the Sami, the natives of northern Scandinavia, is limited. The aim of the present study was to compare gender and cause specific mortality patterns for reindeer herding Sami, non-herding Sami, and non-Sami between 1961 and 2000. METHODS: A Sami cohort was constructed departing from a group of index-Sami identified as either reindeer herding Sami or Sami eligible to vote for the Sami parliament. Relatives of index-Sami were identified in the National Kinship Register and added to the cohort. The cohort contained a total of 41 721 people (7482 reindeer herding Sami and 34 239 non-herding Sami). A demographically matched non-Sami reference population four times as large, was compiled in the same way. Relative mortality risks were analysed by calculating standardized mortality ratios (SMRs). RESULTS: The differences in overall mortality and life expectancy of the Sami, both reindeer herding and non-herding, compared with the reference population were relatively small. However, Sami men showed significantly lower SMR for cancers but higher for external causes of injury. For Sami women, significantly higher SMR was found for diseases of the circulatory system and diseases of the respiratory system. An increased risk of dying from subarachnoid haemorrhage was observed among both Sami men and women. CONCLUSIONS: The similarities in mortality patterns are probably a result of centuries of close interaction between the Sami and the non-Sami, while the observed differences might be due to lifestyle, psychosocial and/or genetic factors.

  • 42.
    Hassler, Sven
    et al.
    University of Gävle, Belastningsskadecentrum.
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Vetenskapliga studier av samernas hälsosituation under senare delen av 1900-talet: en litteraturöversikt2005In: Igår, idag imorgon: Samerna, politiken och vetenskapen / [ed] Peter Sköld och Per Axelsson, Umeå: Centrum för samisk forskning, Umeå universitet , 2005, 93-120 p.Chapter in book (Other (popular science, discussion, etc.))
  • 43. Hassler, Sven
    et al.
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Edin-Liljegren, A
    Daerga, L
    Hjärt-kärlsjukdomar och cancer i den samiska befolkningen2005In: Glesbygdsmedicinska föreningens årsmöte, Arvidsjaur, 2005Conference paper (Other (popular science, discussion, etc.))
  • 44.
    Hassler, Sven
    et al.
    University of Gävle, Belastningsskadecentrum.
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Ericsson, AnnJessica
    Construction of a database on health and living conditions of the Swedish Sami population2004In: Befolkning och bosättning i norr: Etnicitet, identitet och gränser i historiens sken / [ed] Patrik Lantto och Peter Sköld, Umeå: Miscellaneous publications Centre for Sami Research, Umeå University , 2004, 107-124 p.Chapter in book (Refereed)
    Abstract [en]

    Research on the health and living conditions of the Swedish Sami population was initiated at the Southeffi Lapland Research Department in 1998 with the objective to collect and analyse data on lifestyle,environmental exposure, and incidence of various diseases and risk factors that could be used to promote a healthy Sami population. In order to analyse the epidemio.logical data on the Sami population that already exists in national demographic and health registers, a specific database has been constructed containing Swedish Sami. The basis for the construction of the database is the two definitions of Sami identity that are found in Swedish law and are used to regulate the right to register to the electoral register of the Sami parliament, and to regulate the right to breed reindeers. The registers that are connected to these defInitions functions as index registers in the creation of the database. That is, they serve as the starting point from which the expansion of the database takes place. By flnding all household members of the same household as the index persons, the database has expanded from 10 000 individuals in the index registers to a total of more than 150 000 individuals. Local kinship register within the database has also been established making the database more functional in forming Sami cohorts bUilt on family relations. A control part of the database consisting of non-Sami individuals was also formed. The Sami index regi~ters were matched with regard to sex, age and living area to form an index register of non Sami controls which then was extended in a similar way as for the Sami part of the database. An example on how the database can be used is the reconstruction of a Sami population, built on family relations that produced a Sami population that for 1998 amounted to about 44 000 individuals. By opening up new possibilities in seeking information and knowledge, the database can hopefully be come a important tool in the work to improve the health and living conditions of the Sami population of Sweden.

  • 45. Hassler, Sven
    et al.
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Johansson, Robert
    Grönberg, Henrik
    Damber, Lena
    Fatal accidents and suicide among reindeer-herding Sami in Sweden2004In: International Journal of Circumpolar Health, ISSN 1239-9736, Vol. 63 Suppl 2, 384-388 p.Article in journal (Refereed)
    Abstract [en]

    Objective. Over the last decades, reindeer-herding management has experienced drarnatic changes, e.g. increased motorization and socio-econornic pressure. The airn of the present study was to investigate whether these changes have increased the risk of fatal, work-related accidents and suicide between 1961 and 2000. Study design and methods. A c oh ort containing 7,482 members of reindeer-herding Sami families was extracted from national population registers. Information on fatal accidents and suicide was obtained from the Swedish Causes of Death Register, and compared to the expected number of deaths in a dernographica11y matched control population of non-Sami. Results. The ffiale reindeer her- ding Sami showed a significantly increased risk of dying from accidents such as vehicle accidents and poisoning. No significant increased risk of suicide was observed. A comparison between the periods of 1961-1980 and 1981- 2000 showed non-significant differences in risk, although a trend towards incre- ased risks was observed for most types of external causes of death except suicide. Conclusions. It is suggested that the increased socio-econornic pressure and the extensive use of terrain vehicles have increased the risk for fatal accidents arnong Swedish reindeer herders, and that commercial reindeer ma- nagement is one of the most dangerous occupations in Sweden

  • 46.
    Heiden, Marina
    et al.
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Nakata, Minori
    University of Gävle, Belastningsskadecentrum.
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Autonomic activity, pain, and perceived health in patients on sick leave due to stress-related illnesses2005In: Integrative Physiological & Behavioral Science, ISSN 1053-881X, E-ISSN 2168-7846, Vol. 40, no 1, 3-16 p.Article in journal (Refereed)
    Abstract [en]

    Objective: The aim of the present study was to compare autonomic activity, pressure-pain thresholds, and subjective assessments of health and behavior between patients with stress-related illnesses and healthy control subjects. Methods: Twenty sick-listed patients with stress-related disorders and 20 age- and gender-matched healthy subjects performed tests of autonomic regulation and algometric tests, and completed questionnaires about physical and mental health and behavioral patterns. Results: Patients exhibited higher autonomic reactivity to cognitive and physical laboratory tasks (p<0.05), and had lower pressure-pain thresholds in the shoulders and lower back than healthy control subjects (p<0.05). Furthermore, the patients rated considerably poorer health and health behavior than the control subjects (p<0.05). Conclusions: The results indicate an engagement of the autonomic nervous system in stress-related illnesses. Furthermore, they show that patients with stress-related illnesses experience strong symptoms of musculoskeletal pain, and it is therefore recommended that assessments of musculoskeletal pain be incorporated in the clinical examinations and the rehabilitation of patients with stress-related illnesses.

  • 47.
    Heiden, Marina
    et al.
    University of Gävle, Belastningsskadecentrum.
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Hellström, Fredrik
    University of Gävle, Belastningsskadecentrum.
    Crenshaw, Albert G
    Effects of time pressure and precision demands during computer mouse work on muscle oxygenation and position sense.2005In: European journal of applied physiology, ISSN 1439-6319, Vol. 94, no 1-2, 97-106 p.Article in journal (Refereed)
    Abstract [en]

    The present study investigated the effects of time pressure and precision demands during computer mouse work on muscle oxygenation and position sense in the upper extremity. Twenty-four healthy subjects (12 males and 12 females) performed a 45-min standardized mouse operated computer task on two occasions. The task consisted of painting rectangles that were presented on the screen. On one occasion, time pressure and precision demands were imposed (more demanding task, MDT) whereas, on the other occasion, no such restraints were added (less demanding task, LDT). The order of the two task versions was randomized. Tissue oxygen saturation in the trapezius and extensor carpi radialis muscles was recorded throughout, and the position matching ability of the wrist was measured before and after the tasks. In addition, measurements of autonomic nervous system reactivity and subjective ratings of tenseness and physical fatigue were obtained. Performance was measured in terms of the number of rectangles that were painted during the task. During MDT, oxygen saturation in extensor carpi radialis decreased (p<0.05) compared to LDT. These data were paralleled by increased electrodermal activity (p<0.05), skin blood flow (p<0.05), ratings of tenseness and fatigue (p<0.01), and increased performance (p<0.01) during MDT. Females exhibited lower oxygen saturation than males, during rest as well as during the computer tasks (p<0.01). Wrist repositioning error increased following LDT as compared to MDT (p<0.05). In conclusion, computer mouse work under time pressure and precision demands caused a decrease in forearm muscle oxygenation, but did not affect wrist position sense accuracy. We attribute our changes in oxygenation more to increased oxygen consumption as a result of enhanced performance, than to vasoconstriction.

  • 48.
    Heiden, Marina
    et al.
    University of Gävle, Belastningsskadecentrum.
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Nakata, Minori
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Evaluation of Cognitive Behavioral Group Treatment and Physical Activity for People with Stress-related Illnesses2005In: Second ICOH International Conference on Psychosocial Factors at Work, 2005Conference paper (Other academic)
    Abstract [en]

    The aim of the present study was to examine the effects of cognitive behavioral group treatment and physical activity for patients with stress-related illnesses. Sixty patients were randomly allocated to one of three groups, so that each group contained twenty patients. Group A received cognitive behavioral group treatment, group B participated in physical activity, and group C constituted a control group thus receiving no treatment during the course of the study. Measurements of autonomic activity, pain sensitivity, and subjective health assessments were performed before and after a 10-week intervention period, consisting of two gatherings per week for the cognitive behavioral treatment group, and two exercise sessions per week for the physical activity group. Each of the two treatment groups assembled at 1.5, 3, and 6 months after the intervention, and follow-up measurements on all participants were performed at 6 and 12 months after the intervention. For comparison, measurements were performed at one occasion on healthy subjects of the same age and gender distribution as the patients. Patients exhibited higher autonomic reactivity to cognitive and physical laboratory tasks (p<0.05), had lower pressure-pain thresholds in the shoulders and lower back (p<0.05), and rated poorer health than healthy subjects (p<0.01). No overall effect of cognitive behavioral group treatment or physical activity was found on autonomic activity (p>0.06) or pressure-pain thresholds (p>0.71), although patients who received cognitive behavioral group treatment reported improved health (p<0.05). The results suggest little difference in effect of cognitive behavioral group treatment and physical activity on patients with stress-related illnesses

  • 49.
    Hellström, Fredrik
    et al.
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    How to explain the pain: the Brussels model2005In: 6th Physiatric Summer School. Fibromyalgia / [ed] Karl-August Lindgren, Helsinki: Rehabilitation ORTON Invalid Foundation , 2005Conference paper (Other academic)
  • 50.
    Hellström, Fredrik
    et al.
    University of Gävle, Belastningsskadecentrum.
    Roatta, S
    Thunberg, Johan
    University of Gävle, Belastningsskadecentrum.
    Passatore, Magda
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Responses of muscle spindles in feline dorsal neck muscles to electrical stimulation of the cervical sympathetic nerve.2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 165, no 3, 328-42 p.Article in journal (Refereed)
    Abstract [en]

    Previous studies performed in jaw muscles of rabbits and rats have demonstrated that sympathetic outflow may affect the activity of muscle spindle afferents (MSAs). The resulting impairment of MSA information has been suggested to be involved in the genesis and spread of chronic muscle pain. The present study was designed to investigate sympathetic influences on muscle spindles in feline trapezius and splenius muscles (TrSp), as these muscles are commonly affected by chronic pain in humans. Experiments were carried out in cats anesthetized with alpha-chloralose. The effect of electrical stimulation (10 Hz for 90 s or 3 Hz for 5 min) of the peripheral stump of the cervical sympathetic nerve (CSN) was investigated on the discharge of TrSp MSAs (units classified as Ia-like and II-like) and on their responses to sinusoidal stretching of these muscles. In some of the experiments, the local microcirculation of the muscles was monitored by laser Doppler flowmetry. In total, 46 MSAs were recorded. Stimulation of the CSN at 10 Hz powerfully depressed the mean discharge rate of the majority of the tested MSAs (73%) and also affected the sensitivity of MSAs to sinusoidal changes of muscle length, which were evaluated in terms of amplitude and phase of the sinusoidal fitting of unitary activity. The amplitude was significantly reduced in Ia-like units and variably affected in II-like units, while in general the phase was affected little and not changed significantly in either group. The discharge of a smaller percentage of tested units was also modulated by 3-Hz CSN stimulation. Blockade of the neuromuscular junctions by pancuronium did not induce any changes in MSA responses to CSN stimulation, showing that these responses were not secondary to changes in extrafusal or fusimotor activity. Further data showed that the sympathetically induced modulation of MSA discharge was not secondary to the concomitant reduction of muscle blood flow induced by the stimulation. Hence, changes in sympathetic outflow can modulate the afferent signals from muscle spindles through an action exerted directly on the spindles, independent of changes in blood flow. It is suggested that such an action may be one of the mechanisms mediating the onset of chronic muscle pain in these muscles in humans.

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