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  • 51.
    Holmström, Stefan
    et al.
    University of Gävle, Belastningsskadecentrum.
    Molander, Bo
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Job Stress Survey and self-reported health: Evaluating survey stability through repeated measurements in metal-industry workplaces2004In: Proceedings from 36th Annual Conference of the Nordic Ergonomics Society. (NES): Kolding, Denmark, 2004Conference paper (Other academic)
    Abstract [en]

    Level of stress and muskuloskeletal complaints was studied in t wo metal- industry workplaces. Measurements were obtained twice with a 6-month inteIVa!. Level of stress was measured by the Job Stress Survey (Spieiberger & Vagg, 1999). Level of muskuloskeletal complaints was measured by 5-point rating scales. Results showed that the JSS sca!e values, as weil as the muskuloskeletal ratings, were quite stable over the six-month inteIVal. The three JSS scales showed high reliability. The two factories differed with respect to the patteffi of scale values, but these patteros remained over the six months, suggesting that the JSS instrument reflects major stress structures in the factory , rather than occasional changes in production.

  • 52.
    Holmström, Stefan
    et al.
    University of Gävle, Belastningsskadecentrum.
    Molander, Bo
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist,, Margareta
    University of Gävle, Belastningsskadecentrum.
    Job Stress Survey and self-reported health: Repeated measurements in metal-industry2004In: Proceedings from 36th Annual Conference of the Nordic Ergonomics Society. (NES), 2004Conference paper (Other academic)
    Abstract [en]

    Occupational stress and muskuloskeletal complaints was studied in t wo metal-industry workplaces. Measurements were obtained twice with a 6-month interval. Occupational stress was measured by the lob Stress Survey (SpieIberger & Vagg, 1999) and muskuloskeletal complaints was measured by 5-point rating scales. Results showed that the lSS scale values, as weIl as the musculoskeletal pain ratings, were quite stable over the six-month interval. The three lSS scales showed high reliability. The t wo factories differed with respect to the pattern of scale values, but the se patterns remained over the six months, suggesting that the lSS instrument reflects major stress structures in the factory , rather than occasional changes in production.

  • 53.
    Hovelius, Lennart
    et al.
    University of Gävle, Belastningsskadecentrum (t.o.m. 051231).
    Sandström, Björn
    Sundgren, Kent
    Saebö, Modolv
    One hundred eighteen Bristow-Latarjet repairs for recurrent anterior dislocation of the shoulder prospectively followed for fifteen years: Study I - clinical results2004In: Journal of shoulder and elbow surgery, ISSN 1058-2746, E-ISSN 1532-6500, Vol. 13, no 5, p. 509-16Article in journal (Refereed)
    Abstract [en]

    In this prospective study on the Bristow-Latarjet repair, which started in 1980 and ended in 2001, we report the outcome in 118 shoulders where the patients have been followed up for 15 years (mean, 15.2 years; range, 14.3-20.8 years). The study was based on a physical examination, scoring with the system of Rowe et al, and the patients' subjective assessment of the operative result. After 2 years, 1 of 118 shoulders had redislocated and 98% of patients were satisfied with the operative repair. At 15 years' follow-up, 1 patient had undergone revision surgery as a result of recurrence of instability. One patient had had one redislocation during the follow-up period, and one patient reported three recurrences 3 years postoperatively.

    This patient has had no redislocations during the last 12 years. Furthermore, one more patient had had two recurrences 9 and 12 years after surgery but was very satisfied at follow-up. Subluxations occurred once in 4 patients and several times in 7 patients. These patients were, however, satisfied with the procedures at follow-up. One patient reported posterior subluxations at follow-up. Apprehension was significantly more common in patients with bilateral instability (P =.04) and was found in 19 of 109 shoulders. Of the patients, 90 (76%) were very satisfied with the operative result, 26 were satisfied (22%), and 1 did not know. The patient with revision surgery was considered to be dissatisfied. The incidence of bilateral shoulder instability increased from 22 of 118 (19%) at the time of surgery to 41 of 117 (35%) at 15 years after surgery. We conclude that the overall clinical results, with a satisfaction rate of 98% 15 years after the Bristow-Latarjet repair, were as good as the results reported after any operative method for recurrent anterior shoulder dislocation. However, until the radiologic part of this study is completed, we recommend the procedure only for shoulders with revision because of failed previous surgery and to surgeons familiar with the method.

  • 54.
    Häggman-Henrikson, Birgitta
    University of Gävle, Belastningsskadecentrum.
    Neck function in rhythmic jaw activities2004Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Previous studies in animals and humans show anatomic and physiological connections between the trigeminal and cervical regions. This investigation tested the hypothesis of a functional integration between the human jaw and neck motor systems in rhythmic jaw activities. By means of a wireless optoelectronic 3-D movement recording system, spatiotemporal characteristics of mandibular and head-neck movements were studied during rhythmic jaw opening-closing and chewing tasks, in healthy and in individuals with pain and dysfunction in the jaw and neck region following neck trauma, Whiplash-associated Disorders (W AD). As a basis, a methodological study evaluated the applicability of skin and teeth attached reflex markers fixed to the lower jaw and to the head in optoelectronic recording of chewing movements. The results showed concomitant and coordinated mandibular and head movements during rhythmic jaw tasks. The start of the head movement generally preceded the start of the mandibular movement. For chewing, larger size and harder texture of bolus were associated with larger head extension and larger amplitude of both mandibular and head movements. Immobilization of the head by mechanical fixation deranged jaw motor behaviour with regard to speed and amplitude of mandibular movements. Even with head fixation, muscle activity was present in neck muscles during activities. Compared to healthy subjects, WAD individuals show ed smaller amplitudes and disturbed coordination of mandibular and head movements. Furthermore, a dynamic load test showed a reduced endurance during chewing in the W AD group. In conclusion, the results suggest that optimal jaw function requires free unrestricted head-neck movements and support the hypothesis of a close functional relationship between the jaw and the neck regions in rhythmic jaw activities. A new concept for human jaw function is proposed, in which "functional jaw movements" are the result of activation of jaw as weil as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital and cervical spine joints. The finding of an association between neck injury and disturbed jaw behaviour suggest that assessment and management of neck injured patients should include jaw function.

  • 55.
    Häggman-Henrikson, Birgitta
    et al.
    University of Gävle, Belastningsskadecentrum.
    Eriksson, Per-Olof
    University of Gävle, Belastningsskadecentrum.
    Head movements during chewing: relation to size and texture of bolus.2004In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 83, no 11, p. 864-868Article in journal (Refereed)
    Abstract [en]

    Coordinated manibular and head-neck movements during jaw opening-closing activities suggest a close functionallinkage between the jaw (Th and the neck regions. The present study al., investigated whether size and texture of bolus can texl intluence head-neck behavior during chewing. Ho' Using an optoelectronic 3-D recording technique, et , we analyzed concomitant mandibular and head- and neck movements in 12 healthy adults chewing small (3 g) and large (9 g) boluses of chewing resl gum and Optosil. The main finding was a head sim extension during chewing, the amount of which cer' was related mainly to bolus size. Furthermore, suc each chewing cycle was accompanied not only by ya" mandibular movements, but a1so by head mol extension-flexion movements. Larger head the movement amplitudes were correlated with larger but size and, to some extent, also with harder texture yet of the bolus. The results suggest that head-neck of t behavior during chewing is modulated in response acCI to changes in jaw sensory-motor input.

  • 56.
    Häggman-Henrikson, Birgitta
    et al.
    University of Gävle, Belastningsskadecentrum.
    Österlund, C
    Eriksson, Per-Olof
    University of Gävle, Belastningsskadecentrum.
    Endurance during chewing in whiplash-associated disorders and TMD.2004In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 83, no 12, p. 946-50Article in journal (Refereed)
    Abstract [en]

    We have previously shown an association between ncck injury and disturbed jaw function. This study tested the hypothesis of a relationship between neck injury and impaired endurance during chewing. Fifty patients with whiplash-associated disorders (\VAD) were compared with 50 tcmporomandibular disorders (TMD) patients and 50 healthy subjects. Endurance was evaluated during unilateral chewing of gum for 5 min when participants reported fatigue and pain. Whereas aH healthy suhjects complcted the task, 1/4 of the TMD and a majority of the \VAD patients discontinued the task. A majority of the WAD patients also reported fatigue and paln. These ndings suggest an association between neck injury and reduced functional capacity of the jaw motor system. From the results, we propose that routinc cxamination of ‘VAD patients should include jaw function and that an endurance test as described in this study could also be a useful tool for nondental professionals.

  • 57. Jarebrant, C
    et al.
    Öjmertz, B
    Mathiassen, Svend Erik
    University of Gävle, Belastningsskadecentrum.
    Winkel, J
    Ergonova: ergonomisk värdeflödesanalys: verktyget som förenar effektiv produktion och god arbetsmiljö. Arbetsbok2005 (ed. 1)Book (Other academic)
  • 58. Jarebrant, C
    et al.
    Öjmertz, B
    Mathiassen, Svend Erik
    University of Gävle, Belastningsskadecentrum.
    Winkel, Jörgen
    Lunds Tekniska Högskola, Inst för designvetenskap, Lund.
    Ergonova: ergonomisk värdeflödesanalys: verktyget som förenar effektiv produktion och god arbetsmiljö. Handledning2005 (ed. 1. uppl.)Book (Other academic)
  • 59.
    Johansson, Håkan
    et al.
    University of Gävle, Belastningsskadecentrum.
    Windhorst, UweUniversity of Gävle, Belastningsskadecentrum.Djupsjöbacka, MatsUniversity of Gävle, Belastningsskadecentrum.Passatore, MagdaUniversity of Gävle, Belastningsskadecentrum.
    Chronic Work-Related Myalgia: Neuromuscular Mechanisms behind Work-Related Chronic Muscle Pain Syndromes2003Collection (editor) (Other academic)
  • 60.
    Johansson, Håkan
    et al.
    University of Gävle, Belastningsskadecentrum.
    Windhorst, Uwe
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Passatore, Magda
    University of Gävle, Belastningsskadecentrum.
    Kronisk arbetsrelaterad muskelsmärta: Neuromuskulära mekanismer bakom arbetsrelaterade kroniska muskulära smärtsyndrom2004Report (Other academic)
  • 61. Johansson, Åsa
    et al.
    Vavruch-Nilsson, Veronika
    Edin-Liljegren, Anette
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Gyllensten, Ulf
    Linkage disequilibrium between microsatellite markers in the Swedish Sami relative to a worldwide selection of populations2005In: Human Genetics, ISSN 0340-6717, E-ISSN 1432-1203, Vol. 116, no 1-2, p. 105-13Article in journal (Refereed)
    Abstract [en]

    The pattern of linkage disequilibriurn (LD) is affected by a number of factors, including population dernography. High LD is seen in populations with a relatively limited and constant size, presurnably due to genetic drift. We have examined the extent of LD arnong over 300 genome-wide pattern microsatellite loci in 29 populations from around the world. The pattern of LD vari ed between populations, with larger extent of LO in populations with limited size relative to larger populations. In addition, the LD between 88 less spaced microsatellite ffiarkers from 10 different genornic regions were examined in the Sami compared to the general Swedish population. For the se ffiarkers increased LD extending up to 5 Mb was detected in the Sami. The arnount of LD also differed between the chrornosornal regions. The arnount of LD in the Sami makes this population suited for mapping ofcornplex genetic traits

  • 62.
    J:son Lönn, Eva
    University of Gävle, Belastningsskadecentrum.
    Jobb(iga) nyheter: Om dagstidningars bevakning av arbetsmiljöfrågor2005Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    In the beginning of this millennium the increasing level of work related illness was de-scribed, in the public debate, as one of the most serious and costly social problems of our times. An important question in the present study is whether or not the newspapers contributed to make their readers, the politicians and other social actors aware of this vast and growing problem.

    Thus, the main purpose was to find out the extent of the news media coverage on occupational health/ill-health in Swedish newspapers in the end of the 1990s, and the ways in which the topic was framed. Furthermore the intent was to produce a better and deeper understanding of the factors influencing the coverage.

    Theoretically the study draws on framing theory. Framing here refers to the process through which complex issues are reduced to journalistically manageable dimensions in the construction of news stories, resulting in a text, a news story that presents and high-lights some aspects and perspectives of the perceived reality but not others.

    A combination of research methods was used - A content and frame analysis of six months of occupational health coverage in seven newspapers; an interview study with journalists and their scientific sources about the news production; a one week’s news-room study aimed at observing the everyday production of news; and finally, a short email survey directed to the editorial staff at the examined news papers, with the purpose to get some indication on how the coverage of occupational health was organised and prioritized at the different newspapers.

    In the empirical analysis the newspapers´ picturing of occupational health/ill-health was compared with picture emerging from official statistics on occupational sickness and injury. In many respects a deviation was found between the two. Furthermore, simi-larities and differences in content between different newspapers, between different news sections and between news stories written by journalists of different sex, were examined.

    A key finding is that the Swedish newspapers did not draw their readers’ attention to the extensive and growing problem at the places of work. A majority of the stories related to occupational health/ill-health were episodic, and treated the issues as isolated and random events rather than predictable and preventable problems, although there were also more thematic articles written during special circumstances. The results indicate that a primary cause of the topics low priority in the newspapers was that the coverage of occupational health/ill-health had not been integrated into the journalistic routines.

  • 63.
    Kalezic, Ivana
    University of Gävle, Belastningsskadecentrum.
    Experimental studies of spinal mechanisms associated with muscle fatigue2004Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Title Experimental stodies of spinal mechanisms associated with muscle fatigue Abstract Muscle fatigue is ubiquitous in every day life.Muscle fatigue might be considered as an altered state of motor behaviour, which impairs motor performance. By contrast, muscle fatigue could also be considered a positive phenomenon, which protects muscle tissue from damage that might be incurred to it by overose.

    The principal aim of the thesis was to explore some of the mechanisms ofmuscle fatigue at the spinallevel in animal models. The activation of multiple motor units of a single calf muscle may influence contractile properties of its neighbouring, otherwise inactive units, providing evidence for spatial spreading of fatigue between different muscle parts. The release of metabolites, their action on inactive muscle units and the effects oflocal hypoxia are the most likely causes. Fatigue-induced metabolite shift in the interstitium provokes excitation and/or sensitisation of high-threshold afferent fibers, with complex effects on the spinal premotoneuronal network involved in the modulation of motoneuronal output. This was examined by stoding the intrasegmentallamellar distribution of the lumbar spinal intemeurons following fatiguing contractions of the triceps surae muscle. Furthermore, fatigue ofcalfmuscles enhanced the activity of fusimotor neurons to these muscles irrespective of the regime of muscle activity (isometric vs. lengthening) in conditions that simulate locomotion. Altered fusimotor activity, through increased or maintained muscle spindIe arrerent responsiveness may be advantageous, providing support to the skeletomotor activity and enhanced information about muscle periphery to higher nervous centres. The particular effects of intemeuronal network at motor input (presynaptic inhibition system) and output (recurrent inhibition system) stages were then addressed. Fatigue of triceps surae muscle induced a suppression of the monosynaptic reflex. The intensity ofpresynaptic inhibition increased, while the intensity of recurrent inhibition decreased. Post fatigue-evoked changes in monosynaptic reflexes and presynaptic inhibition indicate the possibility that high-threshold afferents inhibit group la terminals pre-synaptically, which would allow fatigue-induced signals from the muscle to reduce the relevance of proprioceptive feedback. Besides intrasegmental, intersegmental spreading of nociceptive signals was explored. Activation of sensory arrerents from dorsal neck muscles by capsaicin induces powerful activation ofintemeurons located in the cervical spinal cord, as weIl as a widespre ad activation of cells in lumbar spinal cord segments.

    The results confirm the pivotal role of small diameter muscle afferents in the orchestration of segmental responses to fatigue and show complex interactions that may lead to limited accuracy of motor output. They also depict processes that may be related to, and even become precursors of chronic muscle pain.

  • 64.
    Kalezic, Ivana
    et al.
    University of Gävle, Belastningsskadecentrum.
    Bugaychenko, Larisa A
    Kostyukov, Alexander I
    Pilyavskii, Alexander I
    Ljubisavljevic, Milos
    University of Gävle, Belastningsskadecentrum.
    Windhorst, Uwe
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Fatigue-related depression of the feline monosynaptic gastrocnemius-soleus reflex2004In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 556, no 1, p. 283-296Article in journal (Refereed)
    Abstract [en]

    In decerebrate cats, changes in the monosynaptic reflex (MSR) of gastrocnemius-soleus (G-S) motoneurones were studied after fatiguing stimulation (FST) of the G-S muscles. Monosynaptic reflexes were evoked by stimulation of Ia fibres in the G-S nerve and recorded from a filament of ventral root (VR) L7. FST (intermittent 40 s(-1) stimulation for 10-12 min) was applied to the distal part of the cut VR S1. FST reduced MSR amplitudes to 0.64 +/- 0.04 (mean +/-s.e.m.) of the prefatigue values. The suppression remained stable for approximately 25 min and then MSR amplitudes gradually returned towards the normal. To test for the involvement of presynaptic and recurrent inhibition, MSRs were conditioned by stimulation of the nerve to the posterior biceps and semitendinosus (PBSt) muscles or a filament of VR L7, respectively. The intensity of presynaptic inhibition (reduction of the normalized value of MSR amplitude during conditioning) increased from 0.19 +/- 0.02 in prefatigue to 0.44 +/- 0.04 within a 5.3-18.2 min interval after FST, followed by a recovery. In contrast, the intensity of recurrent inhibition first diminished from 0.23 +/- 0.02 in prefatigue to 0.15 +/- 0.01 within 15.6-30.1 min after FST and then gradually recovered. Both primary afferent depolarization and the intensity of antidromic discharges in primary afferents increased with the presynaptic inhibition intensity. These results demonstrate a fatigue-related suppression of Ia excitation of synergistic motoneurones, probably arising from the activation of group III and IV afferents. The effects could in part be due to increased presynaptic inhibition, while recurrent inhibition plays a minor role.

  • 65.
    Kalezic, Ivana
    et al.
    University of Gävle, Belastningsskadecentrum.
    Pilyavskii, A I
    Maisky, V A
    Kostyukov, A I
    University of Gävle, Belastningsskadecentrum.
    Windhorst, Uwe
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Distinctive pattern of c-fos expression in the feline cervico-lumbar spinal cord after stimulation of vanilloid receptors in dorsal neck muscles.2004In: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 364, no 2, p. 94-97Article in journal (Refereed)
    Abstract [en]

    In the present study, c-fos expression in the spinal cord has been used as a marker of neuronal activation induced by capsaicin-sensitive sensory afferents from the dorsal neck muscles in cats (n = 6). The number of Fos-immunoreactive neurons, which were revealed using the avidin-biotin-peroxidase method, was significantly increased in the cervical and lumbar spinal cord. In contrast to the control group (n = 3), 2 h after intramuscular capsaicin injection, c-fos expression was more extensive ipsilaterally to the injected side in the C3-C6 segments, and bilaterally in the L4-L6 segments. Most labeled neurons in the cervical spinal cord were small and giant cells, predominantly located in the middle and lateral parts of lamina I and, additionally, at the neck of the dorsal horn (lamina V), i.e., within the zones of termination of high-threshold muscle afferents. The widespread distribution of labeled cells throughout the cervical cord within the intermediate zone (lamina VII) coincided with the sites of last-order premotor interneurons and cells of origin of long crossed and uncrossed descending propriospinal pathways to the lumbar spinal cord. These findings suggest possible mechanisms for spreading of nociceptive signals between cervical and lumbar regions.

  • 66.
    Kalezic, Nebojsa
    et al.
    University of Gävle, Belastningsskadecentrum.
    Åsell, Malin
    Sandlund, Jonas
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Physiological Reactivity to Laboratory Stressors in Patients With Low Back Pain and Whiplash Associated Disorder2004In: Proceedings of the 44th Annual Meeting of The Society for Psychophysiological Research, 2004, p. S75-Conference paper (Other academic)
  • 67. Kazmierczak, Karolina
    et al.
    Mathiassen, Svend Erik
    University of Gävle, Belastningsskadecentrum.
    Forsman, Mikael
    Winkel, Jørgen
    An integrated analysis of ergonomics and time consumption in Swedish 'craft-type' car disassembly.2005In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 36, no 3, p. 263-73Article in journal (Refereed)
    Abstract [en]

    Car disassembly is at the edge of extensive rationalisations due to increased legislative demands for recycling. This study focused on (1) assessing current mechanical exposures (physical work loads) for comparison with future rationalised systems, with particular emphasis on time aspects, (2) analysing disassembly work in terms of time consumption and exposures in constituent tasks as defined by a loss analysis technique, and (3) predicting the consequences of car disassembly rationalisation for mechanical exposures. The study showed that disassembly implied pronounced circulatory loads, and that more walking and higher lumbar peak loads were found than in studies of assembly work. Value-adding tasks comprised 30% of the total working time, and implied higher postural exposures for the head, arm, trunk and wrist, as well as less opportunities to recover, as compared to non-value-adding tasks. Organisational-type rationalisations can be expected to increase the time spent in value-adding work, thus increasing local exposures for the average worker, while a concurrent increase in mechanisation level might reduce circulatory exposures, the amount of walking, and peak lumbar loads.

  • 68.
    Kihlberg, Steve
    et al.
    Malmö högskola, Teknik och samhälle, Malmö.
    Franzon, Helena
    Arbetsmiljöverket, Stockholm.
    Fröberg, Jan
    Arbetslivsinstitutet, Ergonomiprogrammet, Stockholm.
    Hägg, Göran
    Arbetslivsinstitutet, Ergonomiprogrammet, Stockholm.
    Johansson Hanse, Jan
    Göteborgs Universitet, Psykologiska institutionen, Göteborg.
    Kjellberg, Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för inomhusmiljö.
    Mathiassen, Svend Erik
    University of Gävle, Belastningsskadecentrum.
    Medbo, Per
    Chalmers Tekniska Högskola, avd för logistik och transport, Göteborg.
    Neumann, Patrick
    Lunds Tekniska Högskola, Inst för designvetenskap, Lund.
    Winkel, Jörgen
    Lunds Tekniska Högskola, Inst för designvetenskap, Lund.
    Ett produktionssystem under förändring: ergonomisk och teknisk utvärdering2005Book (Other academic)
    Abstract [en]

    An evaluation of the impact of partial automation strategies on productivity and ergonomics at an electronics company was performed. This change included adoption of a serial line flow from a parallel batch flow strategy. The change process, which used both a project head group and a work organisation group, was also studied. The partial automation of assembly operations reduced the total repetitive assembly work at the system level and increased productivity. At the remaining assembly stations however, the repetitive assembly work increased due to the automation of the transportation functions and increased work-pace. The operators found the mental work load was higher in the new system. They also experienced the manual assembly station in the beginning of the line as the worst job in the system . Lack of management continuity at the department was identified as one of the largest process problems. The manager set his view on how the production and work environment goals should be met. Thus the manager set the work organisation without adopting the plan of work rotation that the work organisation group had presented. This contributed to dissatisfaction amongst the operators involved in the development process.

  • 69. Kjellgren, Daniel
    et al.
    Thornell, Lars-Eric
    University of Gävle, Belastningsskadecentrum.
    Virtanen, Ismo
    Pedrosa-Domellöf, Fatima
    University of Gävle, Belastningsskadecentrum.
    Laminin isoforms in human extraocular muscles2004In: Investigative Ophthalmology and Visual Science, ISSN 0146-0404, E-ISSN 1552-5783, Vol. 45, no 12, p. 4233-4239Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To determine the laminin isoform composition of the basement membranes (BMs) in the human extraocular muscles (EOMs) and relate it to the fact that EOMs are spared in laminin alpha2-chain-deficient congenital muscular dystrophy. METHODS: Samples from adult human EOMs and limb muscle were processed for immunocytochemistry, with monoclonal antibodies against laminin chains (Ln) alpha1 to -5, beta1 and -2, and gamma1. Neuromuscular junctions (NMJs) were identified with acetylcholinesterase reaction. The capillary density was measured in sections stained with anti-Lnalpha5. RESULTS: The extrasynaptic BM of the EOM muscle fibers contained Lnalpha2, -beta1, -beta2, and -gamma1, and, in contrast to limb muscle, it also contained Lnalpha4 and -alpha5, to some extent. The distinct laminin composition of the EOMs was confirmed by the presence of Lutheran protein, an alpha5-chain-specific receptor not found in limb muscle. At the NMJs, there was increased expression of Lnalpha4 and expression of Lnalpha2, -alpha5, -beta1, -beta2, and -gamma1 was also maintained. The capillary density was very high (1050 +/- 190 capillaries/mm(2)) in the EOMs and significantly (P < 0.05) higher in the orbital (1170 +/- 180 capillaries/mm(2)) than in the global (930 +/- 110 capillaries/mm(2)) layer. CONCLUSIONS: The human EOMs showed important differences in laminin isoform composition and capillary density when compared with human limb muscle and muscles of other species. The presence of additional laminin isoforms other than laminin-2 in the BM of the extrasynaptic sarcolemma could partly explain the sparing of the EOMs in Lnalpha2-deficient congenital muscular dystrophy.

  • 70.
    Korotkov, A
    University of Gävle, Belastningsskadecentrum.
    Brain processing of experimental muscle pain and its interrelation with proprioception and muscle fatigue: positron emission tomography study2005Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Chronic muscle pain is a significant medical and social problem and better understanding of the pathophysiological mechanisms involved is an important requirernent for further development of diagnostics, treatment and rehabilitation methods. Experimental imaging studies have investigated functional neuroanatomy of different pain cornponents. However, several aspects ofbrain mechanisrns underlying brain processing ofmuscle pain rernain unclear.

    The general goal of the present thesis was to study functional brain anatomy of systerns underlying perception ofmuscle pain, processing ofproprioceptive information and maintenance of fatiguing muscle contractions with an ernphasize on their possible interrelations.

    Four series of experiment were carried out. Using an injection of hypertonic saline (HS) into the m. triceps to induce pain comparable with clinical muscle pain a significant activation of in sula and putamen as weIl as decrease of activit y in the temporal and occipital cortex in comparison with control stimulation were revealed. An advanced model of prolonged muscle pain were provided by the infusion of the HS during 20 minutes into m. erector spinae A cornplex dynamics of brain activit y during the habituation to nociceptive stimulation was shown: initial activation of insula changed to decrease of activit y in this and several other cortical areas. A conjunction analysis identified activations jointly significant in both experiments (despite localization of HS nociceptive stimulation) in the right insula, occipital and left parietal cortical areas. The study of brain activit y in response to different modalities of prorioceptive inputs - passive movernents, kinesthetic illusions and muscle vibration showed corresponding different patteros of activation in motor and sornatosenory areas and temporal areas. Finally, the study of sustained isometric muscle contractions of various force levels and durations revealed that muscle fatigue is associated with contralateral activation of the motor and sornatosensory areas and temporal areas and bilateral activation in the supplementary motor areas and cingular cortex, indicating that increased efforts needed to maintain required force and its eventual breakdown with fatigue might induce activation of additional cortical areas. Analysis of data obtained in all experimental series revealed that insula, secondary sornatosensory and auditory areas are activated during both perception of muscle pain and processing of somatosensory afferentation.

    In conclusion, this thesis has elucidated brain processing of muscle pain showing distributed, bilateral patteros cornprised of activated structures predominantly attributed to the medial pain system and deactivated structures. Furthermore, initial and late phases of tonic muscle pain are associated with different brain reactions, namely initial activation of the insula followed by a significant bilateral decrease of activit y at the late stage. Area of brain cortex located near lateral sulcus and cornprised of secondary sornatosensory cortex, posterior part of the insula and adjacent auditory cortex is engaged in the perception of muscle pain and processing of sornatosensory afferentation as weIl as rnaintenance of fatiguing muscle contractions.

  • 71.
    Korotkov, Alexander
    et al.
    University of Gävle, Belastningsskadecentrum.
    Radovanovic, Sasa
    University of Gävle, Belastningsskadecentrum.
    Ljubisavljevic, Milos
    University of Gävle, Belastningsskadecentrum.
    Lyskov, Eugene
    University of Gävle, Belastningsskadecentrum.
    Kataeva, Galina
    Roudas, Marina
    Pakhomov, Sergey
    Thunberg, Johan
    University of Gävle, Belastningsskadecentrum.
    Medvedev, Sviatoslav
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Comparison of brain activation after sustained non-fatiguing and fatiguing muscle contraction: a positron emission tomography study.2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 163, no 1, p. 65-74Article in journal (Refereed)
    Abstract [en]

    The concept of fatigue refers to a class of acute effects that can impair motor performance, and not to a single mechanism. A great deal is known about the peripheral mechanisms underlying the process of fatigue, but our knowledge of the roles of the central structures in that process is still very limited. During fatigue, it has been shown that peripheral apparatus is capable of generating adequate force while central structures become insufficient/sub-optimal in driving them. This is known as central fatigue, and it can vary between muscles and different tasks. Fatigue induced by submaximal isometric contraction may have a greater central component than fatigue induced by prolonged maximal efforts. We studied the changes in regional cerebral blood flow (rCBF) of brain structures after sustained isometric muscle contractions of different submaximal force levels and of different durations, and compared them with the conditions observed when the sustained muscle contraction becomes fatiguing. Changes in cortical activity, as indicated by changes in rCBF, were measured using positron emission tomography (PET). Twelve subjects were studied under four conditions: (1) rest condition; (2) contraction of the m. biceps brachii at 30% of MVC, sustained for 60 s; (3) contraction at 30% of MVC, sustained for 120 s, and; (4) contraction at 50% of MVC, sustained for 120 s. The level of rCBF in the activated cortical areas gradually increased with the level and duration of muscle contraction. The fatiguing condition was associated with predominantly contralateral activation of the primary motor (MI) and the primary and secondary somatosensory areas (SI and SII), the somatosensory association area (SAA), and the temporal areas AA and AI. The supplementary motor area (SMA) and the cingula were activated bilaterally. The results show increased cortical activation, confirming that increased effort aimed at maintaining force in muscle fatigue is associated with increased activation of cortical neurons. At the same time, the activation spread to several cortical areas and probably reflects changes in both excitatory and inhibitory cortical circuits. It is suggested that further studies aimed at controlling afferent input from the muscle during fatigue may allow a more precise examination of the roles of each particular region involved in the processing of muscle fatigue.

  • 72. Kostyukov, Alexander I
    et al.
    Bugaychenko, Larisa A
    Kalezic, Ivana
    University of Gävle, Belastningsskadecentrum.
    Pilyavskii, Alexander I
    Windhorst, Uwe
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Effects in feline gastrocnemius-soleus motoneurones induced by muscle fatigue.2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 163, no 3, p. 284-94Article in journal (Refereed)
    Abstract [en]

    Responses of gastrocnemius-soleus (G-S) motoneurones to stretches of the homonymous muscles were recorded intracellularly in decerebrate cats before, during and after fatiguing stimulation (FST) of G-S muscles. Ventral roots (VR) L7 and S1 were cut, and FST was applied to VR S1, a single FST session including 4 to 5 repetitions of 12-s periods of regular 40 s(-1) stimulation. Muscle stretches consisted of several phases of slow sinusoidal shortening-lengthening cycles and intermediate constant lengths. The maximal stretch of the muscles was 8.8 mm above the rest length. Effects of FST on excitatory postsynaptic potentials (EPSPs) and spikes evoked by the muscle stretches were studied in 12 motoneurones from ten experiments. Stretch-evoked EPSPs and firing were predominantly suppressed after FST, with the exception of a post-contraction increase of the first EPSP after FST, which was most likely due to after-effects in the activity of muscle spindle afferents. The post-fatigue suppression of EPSPs and spike activity was followed by restoration within 60-100 s. Additional bouts of FST augmented the intensity of post-fatigue suppression of EPSPs, with the spike activity sometimes disappearing completely. FST itself elicited EPSPs at latencies suggesting activation of muscle spindle group Ia afferents via stimulation of beta-fibres. The suppression of the stretch-evoked responses most likely resulted from fatigue-evoked activity of group III and IV muscle afferents. Presynaptic inhibition could be one of the mechanisms involved, but homosynaptic depression in the FST-activated group Ia afferents may also have contributed.

  • 73. Laczko, Jozsef
    et al.
    Jaric, Slobodan
    University of Gävle, Belastningsskadecentrum.
    Domkin, Dmitry
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Latash, Mark L.
    Stabilization of kinematic variables in the control of bimanual pointing movements2001In: Proceedings of the International joint conference on neural networks, 2001, p. 1256-1260Conference paper (Refereed)
    Abstract [en]

    Human voluntary movements face a problem of kinematic redundancy: The number of degrees of freedom for the peripheral mechanical apparatus (e.g., a Iimb) is higher than the number of variables necessary to describe movement execution. Thus, there is an infinity of different ways to execute a given motor task. The recently developed Uncontrolled Manifold (UCM) hypothesis suggests that the central nervous system (CNS) generates solutions such that important task related variables are selectively stabilized. Each motor task is associated with stabilizing a .time series of a task variable. At each instant, the CNS selects, in the state space af elements participating in the task, a manifold (UCM) corresponding to a fixed value of the selected task variable. We study a planar bìmanual task, when one hand moves a target and the other hand moves a pointer that must reach the target. We hypothesized that the stabilized task variable was the vectorial difference of the pointertip and the target. The 6 dimensional state space was defined bys 'joint configuration vectors" whose elements were intersegmental joint angles (shoulder, elbow and wrisst in both arms). The subjects repeated the movements IS times, and the movements were recorded by a movement analysis system. Then, the subjects practiced the movements (300 trials). After practice IS trials were recorded again. We computed the variance of the joint configurations before and after practice. Six joint rotations affected the 2 dimensional task variable. The UCM corresponding to this variable is 4- dimensional, while the subspace of the state space that is orthogonal (ORT) to the UCM is 2-dimensional. The variance within the UCM was larger than in the ORT conforming to the UCM hyphothesis. After practice the joint variance decreased and the drop in the component of variance that did not affect the task vaeriable was larger thnn the drop 'of the other component. Thus, practice lead to more stable time courses of the task variable and of the corresponding joint configuration.

  • 74. Lee, Edward W
    et al.
    Kítlinska, Johanna B
    Kuo, Lydia E
    Michalkiewicz, Mieczyslaw
    Kalezic, Ivana
    University of Gävle, Belastningsskadecentrum.
    Ljubisavlejvic, Milos
    University of Gävle, Belastningsskadecentrum.
    Zukowska, Zofia
    Neuropeptide Y (NPY): A neurogenic mediator of angiogenesis2004In: 7th International NPY Meeting Coimbra, 2004, p. 36-36Conference paper (Other academic)
    Abstract [en]

    NPY, previously known as a sympathetic vasoconstricting co-transmitter, recently has also emerged as an important vascular growth factor, stimulating proliferation of vascular smooth muscle and endothelial cells (ECs). Both in vitro and in vivo, NPY stimulates angiogenesis starting at sub-picomolar, non-vasoconstrictive concentrations, and with maximal effects similar to those of other known angiogenic factors e.g. vascular endothelial growth factor (VEGF). To determine if NPY is a physiological mediator in vivo, we studied 1 ) ischemic angiogenesis in a rodent model of femoral artery occlusion 2) vascular development in rats over-expressing NPY gene; 3) changes in angiogenesis with aging. Hindlimb ischemia increased local NPY release and shifted NPY receptor (R) expression from predominantly Yl to the Y2R type, and up-regulated dipeptidyl peptidase IV (DPPIV, peptidase forming Y2/YS agonist). Increasing local NPY levels 2-fold with a slow-release pellet (Il.g/14 days, below arterial occlusion), additionally induced YSR mRNA, and stimulated capillary angiogenesis and collateral vessel growth - leading to restoration of blood flow and contractile function of ischemic muscles. These effects were markedly reduced in Y2R-/- mice, as was NPY-induced aortic sprouting ex vivo; the latter was also reduced by anti-VEGF antibody and completely abolished in endothelial nitric oxide synthase (eNOS)-/- mice. The role of NPY in vascular development was further revealed by the severe impairment of spontaneous aortic sprouting in NPY-/- mice and changes in vascular density of non-ischemic muscles: reduction in Y2-/- mice and marked increase in NPY-Tg rats. With aging, in mice, NPY-induced angiogenesis decreased together with Y2 and DPPIV expression, and in human ECs, the proliferative effects of NPY declined too, similarly to those of VEGF or basic fibroblast growth factor (bFGF). Since NPY-induced EC proliferation was similarly blocked by anti-VEGF and anti-FGF antibodies in young and old patients, this suggests that age-induced impaired activity of the NPY-Y2R system could lead to lower secretion of these growth factors, in addition to decreased responsiveness of old vessels to VEGF and bFGF. Taken together, our studies indicate that NPY is a physiological neurogenic factor playing an important role ip revascularization of ischemic tissues and in age-related changes in vascular development. NPY's angiogenic activity requires Y2Rs and eNOS, and involves release of VEGF and bFGF. Thus, sympathetic nerve activity, via NPY, may be an important upstream mechanism triggering a cascade of molecular events leading to vascular remodeling during tissue ischemia and growth.

  • 75.
    Liu, Jing-Xia
    University of Gävle, Belastningsskadecentrum.
    Human muscle spindles: Complex morphology and structural organisation2004Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    lntroduction: Muscle spindIes are skeletal muscle mechanoreceptors that mediate the stretch reflex and provide axial and limb position information to the central nervous system. They

    have been proposed to playamajor role in the pathophysiology of muscle pain. Knowledge about the normal human muscle spindIes is needed in order to understand their role in muscle disease or dysfunction.

    The aim of this study was to investigate the fiber content and MyHC composition of the muscle spindIes in the human biceps brachii (88) and deep muscles of the neck (DN); to determine whether there are age-related changes in human muscle spindIes with respect to structure and MyHC composition; to investigate the distribution of SERCA isoforms and to evaluate whether there is a coordinated expression of SERCA and MyHC isoforms in intrafusal fibers. The myosin heavy chain (MyHC) content correlates to contraction velocity and force and the sarcoplasmic reticulum Ca2+ ATPase (SERCA) is a major determinant ofmuscle fiber relaxation velocity .

    Methods: Muscle specimens obtained from young and old subjects were serially sectioned and the pattem of distribution of different proteins along the length of the intrafusal fibers was revealed by immunocytochemistry .The MyHC content of single muscle spindIes was assessed with SDS-PAGE and immunoblots.

    Results: There were clear differences between 88 and DN with regard to the morphology and MyHC composition of muscle spindIes. Virtually each muscle spindIe in th~ 88, but not in the DN, had a unique allotment of numbers of bagl, bag2 and chain fibers. In DN, a number of muscle spindIes lacked either bagl or bag2 fibers. Four major MyHC isoforms (MyHCI, Ila, a.- cardiac and intrafusal) were detected by SDS-PAGE. In both 88 and DN, immunocytochemistry revealed co-expression of several MyHC isoforms in each intrafusal fiber and regional heterogeneity. 8oth nuclear bagl and bag2 fibers contained slow tonic MyHC uniformly and MyHCI, a.-cardiac, embryonic and fetal with regional variations. Nuclear chain fibers contained MyHCIla, embryonic and fetal and in the 88 also MyHCIIx.

    The total number of intrafusal fibers per spindIe decreased significantly with aging, due to a significant reduction in the number of nuclear chain fibers. The patterns of MyHC expression were also affected by aging.

    The bagl fibers predominantly contained both SERCA isoforms in the encapsulated region. The bag2 fibers were more heterogeneous in their SERCA composition and 16-27% of them lacked both isoforms. Chain fibers contained SERCAI. There was a poor correlation between the MyHC and SERCA isoforms in nuclear bag fibers, whereas a strong correlation existed between MyHCIla and SERCAI in the nuclear chain fibers.

    Conclusions: Human muscle spindles, each being unique, proved to be more complex than anticipated. The clear differences shown between the 88 and DN muscle spindIes suggest functional specialization in the control of movement among different human muscles. Aging apparently had profound effects on intrafusal fiber content and MyHC composition. The age- related changes in muscle spindIe phenotype may reflect deterioration in sensory and motor innervation and are likely to have a detrimental impact on motor control in the elderly.

  • 76.
    Lyskov, Eugene
    et al.
    University of Gävle, Belastningsskadecentrum.
    Hansson Mild, Kjell
    Sandström, Monica
    Sensor reactivity and autonomous regulation in persons with perceived electrical hypersensitivity2004In: Proceedings of the WHO International Seminar and Working Group meeting on EMF Hypersensitivity, 2004Conference paper (Other (popular science, discussion, etc.))
  • 77.
    Lyskov, Eugene
    et al.
    University of Gävle, Belastningsskadecentrum.
    Hansson Mild, Kjell
    Sandström, Monica
    Kalezic, Nebojsa
    University of Gävle, Belastningsskadecentrum.
    Alexanyan, Z
    Medvedev, S
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Altered stress response as a possible mechanism of idiopathic environmental intolerance: Physiological findings and diagnostic perstrespectives2004In: Psychopharmacology & biological narcology: 8th Conference Stress and Behavior, 2004Conference paper (Other (popular science, discussion, etc.))
  • 78.
    Lyskov, Eugene
    et al.
    University of Gävle, Belastningsskadecentrum.
    Kalezic, Nebojsa
    University of Gävle, Belastningsskadecentrum.
    Markov, Marko
    Mild, Kjell Hansson
    Thunberg, Johan
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Low frequency therapeutic EMF differently influences experimental muscle pain in female and male subjects.2005In: Bioelectromagnetics, ISSN 0197-8462, E-ISSN 1521-186X, Vol. 26, no 4, p. 299-304Article in journal (Refereed)
    Abstract [en]

    Effects of a pulsating, half sine wave magnetic field (MF) with a frequency of 100 pps and 15 mT rms flux density, generated by the MD TEMF device (EMF Therapeutics, Inc., Chattanooga), on subjective pain rating, heart rate, and arterial blood pressure were tested in a double blind, crossover design study employing experimental muscle pain. Each of 24 healthy volunteers (12 females and 12 males, 24.7 +/- 3.2 years of age) received painful stimulation induced by the infusion of 5% hypertonic saline (HS) into the erector spinae muscle during real and sham MF exposure, in counterbalanced order. Exposure to MF differently affects subjective pain estimates in females and males. MF exposure increased averaged pain level and time integral of pain ratings in females, whereas no statistically significant difference for these characteristics was found in males. Pain related elevation of systolic and diastolic blood pressure was observed during both real and sham EMF exposure in female and male subjects.

  • 79.
    Lyskov, Eugene
    et al.
    University of Gävle, Belastningsskadecentrum.
    Kalezic, Nebojsa
    University of Gävle, Belastningsskadecentrum.
    Sandlund, Jonas
    University of Gävle, Belastningsskadecentrum.
    Hamberg, Jern
    Physiological responsiveness to stressing test in patients with neck pain2004In: International Congress on Chronic Pain and Dysfunction after Whiplash and other Traumatic Neck Injuries, Gävle: Gävle University Press , 2004, p. 49-51Conference paper (Refereed)
  • 80.
    Mathiassen, Svend Erik
    et al.
    University of Gävle, Belastningsskadecentrum.
    Nordander, Catarina
    Department of Occupational and Environmental Medicine, Lund University Hospital.
    Svendsen, Susanne W
    Department of Occupational Medicine, University Hospital of Aarhus, Aarhus, Denmark.
    Wellman, Helen M
    Liberty Mutual Research Institute for Safety, Hopkinton, Massachusetts.
    Dempsey, Patrick G
    Liberty Mutual Research Institute for Safety, Hopkinton, Massachusetts.
    Task-based estimation of mechanical job exposure in occupational groups2005In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 31, no 2, p. 138-51Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: This study examined the validity of a common belief in epidemiology with respect to work-related musculoskeletal disorders, that individual mechanical job exposure is better estimated from tasks performed in the job than from the mean exposure of the occupational group. METHODS: Whole-day recordings of upper trapezius electromyography were obtained from 24 cleaners and 23 office workers. Trapezius activity was analyzed in the level (gap time) and frequency (jerk time) dimensions. On the same day, the job of each person was divided into periods of active work and breaks by means of continuous observations. The bootstrap re-sampling technique was used with this database to compare task-based job exposure estimates with estimates based on the occupational mean. For a particular person, the task-based estimate was obtained by combining the average work and break exposures in the occupation with the personal time proportions of the two tasks in the job. RESULTS: The task-based estimates were, in general, equivalent to, or less correct than, occupation-based estimates for both exposure parameters in both occupations and for individual exposures, as well as for group means. This was the result in spite of significant and consistent exposure differences between work and breaks, in particular among the cleaners. CONCLUSIONS: Even if task exposure contrasts are large, task-based estimates of job exposures can be less correct than estimates based on the occupational mean. Since collecting and processing task information is costly, it is recommended that task-based modeling of mechanical exposure be implemented in studies only after careful examination of its possible benefits.

  • 81.
    Michaelson, Peter
    University of Gävle, Belastningsskadecentrum.
    Sensorimotor characteristics in chronic neck pain: Possible pathophysiological mechanisms and implications for rehabilitation2004Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    The general aims of this thesis was to investigate the predictive value of physical, sociodemographic, and psychosocial-behavioural variables for pain reduction arter multimodal rehabilitation in patients with chronic low back or neck pain, and to develop and evaluate tests for objective and quantitative evaluation of characteristic sensorimotor disturbances in chronic neck pain.

    Logistic regression ffiodels revealed that unchanged pain intensity could be predicted with good precision while reduced pain intensity arter rehabilitation was poorly predicted by the baseline variables. Altered pain intensity in chronic low back pain was predicted by high pain intensity, low levels of pain severity and high affective distress, while reduced pain intensity for patients with chronic neck pain were predicted by high endurance, low age, high pain intensity, low need ofbeing social along with optirnistic attitudes on how the pain will interfere with daily life, and few vegetative symptorns. One of the conclusions was that objective measures of specific sensorimotor disturbances should improve the precision by which treatment-induced effects can be assessed and predicted.

    A study was designed to objectively and quantitatively evaluate a large numbers of different sensorimotor characteristics in a small group of patients with chronic neck pain of different aetiology (whiplash-related and insidious). Kinernatic data was recorded during different motor tasks, involving cervical rotations, arm ffiovements and standing. In comparison to a group of asymptomatic control subjects, patients with chronic neck pain was characterised by slower ffiovements, poor balance, reduced cervical stability during perturbations, altered smoothness of ffiovement (jerk index), and reduced ffiovement precision (variable error and variability in range of motion). The sensorimotor variables velocity ofarm ffiovements and cervical stability, could correctly classified nearly 90% of the subjects as having chronic neck pain or being asymptomatic.

    There was a large diversity of sensorimotor disturbances among the individual patients. This was conflrmed in a regression ffiodel that failed to separate the groups insidious neck pain (sensitivity 44%) and WAD (sensitivity 67%).

    By investigating associations between the different sensorimotor variables, close relations was found between the repositioning acuity and variability in range of motion, and between standing balance and cervical stability! standing balance during perturbation. These two groups of variables were only weakly related to each other and to smoothness offfiovement and ffiovement velocity.

    The results indicate that chronic neck pain is characterised by specific sensorimotor deficits, and that there are common pathophysiological mechanisrns in chronic neck pain of different aetiology. However, the lack of associations between several sensorimotor disturbances indicates that different mechanisrns are involved. The thesis indicates that objective sensorimotor tests should be used to improve the quaIity of functional assessments in chronic neck pain. Methods that objectively and quantitatively measure e.g. ffiovement precision, balance and cervical stability are also needed in order to evaluate current treatment methods and to develop new rehabilitation prograrns for specific sensorimotor deficits.

  • 82.
    Michaelson, Peter
    et al.
    University of Gävle, Belastningsskadecentrum.
    Michaelson, M
    Jaric, Slobodan
    University of Gävle, Belastningsskadecentrum.
    Latash, M L
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Head stability and vertical posture in patients with whiplash associated disorders and work related neck pain2004In: Proceedings of the 8th International Federation of Orthopaedic Manipulative Therapists' Conference, 2004Conference paper (Other (popular science, discussion, etc.))
  • 83.
    Michaelson, Peter
    et al.
    University of Gävle, Belastningsskadecentrum.
    Sjölander, Per
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Factors predicting pain reduction in chronic back and neck pain after multimodal treatment2004In: The Clinical Journal of Pain, ISSN 0749-8047, E-ISSN 1536-5409, Vol. 20, no 6, p. 447-454Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To determine whether treatment related pain reduction on the short- and long-term is predicted by different baseline variables, and with different accuracy, in patients with chronic low back pain as compared with those with chronic neck pain. DESIGN AND METHODS: A single blinded prospective cohort study based on patients with chronic musculoskeletal pain in the lower back (N = 167) or the neck (N = 136) who completed a 4-week multimodal rehabilitation program. At admission, each patient was evaluated on 17 potential predictors, including pain characteristics and physical, sociodemographic, and psychosocial-behavioral variables. Changes in self-reported pain intensity in the lower back or the neck between the pretreatment evaluation and those performed immediately after, and 12 months after the rehabilitation program, were assessed. RESULTS: Logistic regression models revealed that change in pain intensity could be predicted with good specificity but with poor sensitivity both for patients with chronic low back pain and chronic neck pain. Significant predictors among the neck pain patients were high endurance, low age, high pain intensity, few other symptoms, low need of being social, to do things with others, and to be helped, along with optimistic attitudes on how the pain will interfere with daily life. Among the low back pain patients, high pain intensity, low levels of pain severity, and high affective distress were important predictors. Variables such as sex, sick leave history, working status, accident, pain duration, and depressive symptoms demonstrated no predictive value. Short- and long-term pain outcome was equally predictable and predicted by almost the same variables. CONCLUSIONS: Patients who reported unchanged or increased pain after multimodal treatment could be predicted with good accuracy, whereas those who reported decreased pain were more difficult to identify. Treatment-related pain alteration in chronic low back pain seems to be predicted by partly different variables than in chronic neck pain.

  • 84.
    Nakata, Minori
    University of Gävle, Belastningsskadecentrum.
    Current situation of and preventive activities forwork-related musculoskeletal diseases in Europe2004In: Proceedings of the 77th Annual Conference of the Japan Society for Occupational Health: Nagoya, Japan, April 13-16, 2004Conference paper (Other (popular science, discussion, etc.))
  • 85.
    Nakata, Minori
    et al.
    University of Gävle, Belastningsskadecentrum.
    Ahlgren, Christina
    From, Carin
    Lindberg, Per
    University of Gävle, Centre for Musculoskeletal Research.
    Solving tangled cases of work-related musculoskeletal disorders by international scientific cooperation.2005In: NEW SOLUTIONS: A Journal of Environmental and Occupational Health Policy, ISSN 1048-2911, E-ISSN 1541-3772, Vol. 15, no 4, p. 343-56Article in journal (Refereed)
    Abstract [en]

    Work-related musculoskeletal disorders (WRMSDs) have become a serious worldwide problem. At the same time a number of workers experience a problem in getting their WRMSDs acknowledged. As an attempt to solve these problems, Japanese school lunch cooks' working conditions were discussed at international scientific meetings and a detailed inspection was done at a Japanese school kitchen by Swedish researchers. It revealed that both national and international researchers' opinions coincided. Statements of medical views were written for several tangled cases in Japan and Sweden referring to both the national and international literature. As a result, these tangled cases were acknowledged officially as WRMSDs. New arbitrators and mediators of WRMSDs are required who can understand and communicate between the world of medical and labor sciences and also between the world of science and daily work life.

  • 86.
    Nakata, Minori
    et al.
    University of Gävle, Belastningsskadecentrum.
    Eriksson, Per-Olof
    University of Gävle, Belastningsskadecentrum.
    Aasa, Ulrika
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Tenderness in muscles and spinous processes among workers and patients2004In: Proceedings of the 5th International Scientific Conference on Prevention of Work-Related Musculoskeletal Disorders (PREMUS): Zurich, Switzerland, July 11-15, 2004, p. 293-294Conference paper (Other academic)
  • 87.
    Nakata, Minori
    et al.
    University of Gävle, Belastningsskadecentrum.
    Jaric, Slobodan
    University of Gävle, Belastningsskadecentrum.
    Domkin, Dmitry
    University of Gävle, Belastningsskadecentrum.
    Aasa, Ulrika
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    Evaluation of workload in ambulance personnel - A preliminary study2002In: Humans in a Complex Environment: Proceedings of the 34th Annual Congress of the Nordic Ergonomics Society, 2002Conference paper (Refereed)
    Abstract [en]

    Musculotendinous tenderness was evaluated in ambulance personnel, and their working load was studied by means of biomechanical analysis of the standard loading and unloading the `stretcher+patient' in and from the vehicle. Swedish and Japanese subjects were tested. The medical examination demonstrated increased tenderness of selected muscles active in work related movement tasks, as well as in spinous processes in both populations. However, a number ofparticular tests suggested higher Ievel of tenderness in the Swedish, as compared with the Japanese personnel. Biomechanical analysis of working tasks demonstrated similar forces, but higher LS-SI, hip and shoulder torques acting in Swedish personnel. This difference appears to be caused by the differences in stretcher construction. Specifically, the Swedish stretcher requires separate lifting of each stretcher side starting from a squat body position, while the Japanese system requires only pushing the stretcher in and pulling it out from the vehicle. We conclude that differences in working technique imposed by available working equipment could contribute to the observed differences in muscle tenderness especially around the shoulders between the two tested populations. However, further studies are needed to elaborate working load and muscle activity while performing standard tasks of ambulance personnel, as well as to explore other possible causes of increased musculotendinous tenderness. Keywords: Ambulance, Muculoskeletal disorders, Muscle tenderness, Spinous process, Biomechanical analyses

  • 88.
    Nakata, Minori
    et al.
    University of Gävle, Belastningsskadecentrum.
    Noborisaka, Yuka
    University of Gävle, Belastningsskadecentrum.
    Aasa, Ulrika
    University of Gävle, Belastningsskadecentrum.
    Barnekow-Bergkvist, Margareta
    University of Gävle, Belastningsskadecentrum.
    Ishii, Noboru
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    An international comparison of work-related musculoskeletal problems and related factors among ambulance personnel2004In: proceedings of the 5th International Scientific Conference on Prevention of Work-related Musculoskeletal Disorders (PREMUS): ETH Zurich, Switzerland, July 11-15, 2004, p. 313-314Conference paper (Other academic)
  • 89. Okada, Naoki
    et al.
    Ishii, Noboru
    Nakata, Minori
    University of Gävle, Belastningsskadecentrum.
    Nakayama, Shinichi
    Occupational stress among Japanese emergency medical technicians: Hyogo Prefecture.2005In: Prehospital and disaster medicine: the official journal of the National Association of EMS Physicians and the World Association for Emergency and Disaster Medicine in association with the Acute Care Foundation, ISSN 1049-023X, Vol. 20, no 2, p. 115-21Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: As prehospital care became emphasized in emergency medical services in Japan, qualification as a "paramedic" was established in 1991 as a requirement for national qualification as a emergency medical technician (EMT). With recent increases in emergency transportation, the responsibilities of paramedics have become more complex and demand a higher level of competency; however, no method of evaluating occupational stress among Japanese EMTs currently exists.

    METHODS: A questionnaire survey of the working conditions and health of 2,017 EMTs in Hyogo Prefecture was conducted. To analyze stress levels among these EMTs, the survey was divided into two categories: (1) physical stress; and (2) mental stress.

    RESULTS: The number of responses was 1,551 (76.9%) and the average age of the respondents was 35.4 years. The lower back, neck, and shoulders were most frequently subjected to physical stress, which was related to the daily operations as an EMT. Mental stress was reported more frequently by those who were older or qualified paramedics.

    DISCUSSION: The high frequency of lower back pain suggests the need for improvement in the work environment and periodic education.

    CONCLUSIONS: Although job satisfaction among paramedics was high, they were exposed to greater mental stress. Therefore, systematic management of stress must be developed and established.

  • 90.
    Passatore, Magda
    et al.
    University of Gävle, Belastningsskadecentrum.
    Hellström, Fredrik
    University of Gävle, Belastningsskadecentrum.
    Roatta, Silvestro
    The role of the sympathetic nervous system in stress and pain2004In: Proceedings of international Congress on Chronic Pain and Dysfunction after Whiplash and other Traumatic Neck Injuries / [ed] Djupsjöbacka M, Johansson B H, Mathiassen S E, Sjölander P, Gävle: Gefe University Press , 2004, p. 16-26Conference paper (Refereed)
  • 91. Passatore, Magda
    et al.
    Windhorst, Uwe
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Lytvynenko, S
    University of Gävle, Belastningsskadecentrum.
    Roatta, Silvestro
    Effects of sympathetic stimulation on the rhythmic jaw movements produced by electrical stimulation of the rabbit cortical masticatory areas: Possible implication in chronic muscle pain2004In: 4th Forum of European Neuroscience, Lisbon, Portugal, 2004Conference paper (Other academic)
    Abstract [en]

    The somatomotor and sympathetic nervous systems are intimately linked. One example is the influence of peripheral sympathetic fibers on the discharge characteristics of muscle spindles. Since muscle spindles play important roles in various motor behaviors, including rhythmic movements, changes in sympathetic outflow to muscle spindles should change rhythmic movement patterns. We set out to test this hypothesis in the masticatory system of rabbits. Cortically evoked rhythmic jaw movements (CRJMs) and electromyograms (EMGs), induced by long-lasting electrical cortical stimulation, were powerfully modulated by electrical stimulation of the peripheral stump of the cervical sympathetic nerve (CSN). This modulation was characterized by a consistent and marked reduction in the excursion of the mandibular movements (26±10%, mean±STD), often preceded by a transient modest enhancement, which could be mainly attributed to corresponding changes in masseter muscle activity (49±26%). These changes outlasted the duration of CSN stimulation. In some of the CRJMs, changes in masticatory frequency were also observed. When the jaw-closing muscles were subjected to repetitive ramp-and-hold force pulses, the CRMJs changed characteristics. Masseter EMG activity was strongly enhanced (+144±96%) and digastric EMG slightly decreased. This change was considerably depressed during CSN stimulation (to +96±57%). These effects of CSN are similar in sign and time course to the depression exerted by sympathetic activity on the jaw-closing muscle spindle discharge (Roatta et al. 2002). It is suggested that the change in proprioceptive information induced by an increase in sympathetic outflow (i) has important implications for the control of motor function in states of high sympathetic activity, and (ii) is one of the mechanisms responsible for motor impairment under certain pathological conditions such as chronic musculoskeletal head-neck disorders, associated with stress conditions.

  • 92. Pilyavskii, Alexander I
    et al.
    Maznychenko, Andrey V
    Maisky, Vladimir A
    Kostyukov, Alexander I
    Hellström, Fredrik
    University of Gävle, Belastningsskadecentrum.
    Windhorst, Uwe
    Capsaicin-induced effects on c-fos expression and NADPH-diaphorase activity in the feline spinal cord.2005In: European Journal of Pharmacology, ISSN 0014-2999, E-ISSN 1879-0712, Vol. 521, no 1-3, p. 70-78Article in journal (Refereed)
    Abstract [en]

    The distribution of c-fos expression and NADPH-diaphorase reactivity in the cervical and lumbar segments after stimulation of the vanilloid receptors in the dorsal neck muscles with capsaicin was studied in cats anaesthetized with alpha-chloralose. After the unilateral intramuscular injection of capsaicin, the mean number of Fos-immunoreactive neurons detected with an avidin-biotin-peroxidase technique was significantly increased in the superficial laminae (I), neck of the dorsal horn (V), and area around the central canal (VII) within both the cervical and lumbar spinal cord. Most Fos-immunoreactive neurons in the cervical spinal cord were giant and small cells. The widespread distribution of Fos-immunoreactive cells throughout the cervical cord within the intermediate zone (VII) coincided with the sites of localization of last-order premotor interneurons and cells of origin of inter-segmental crossed and uncrossed descending propriospinal pathways to the lumbar spinal cord. Fos-immunoreactive neurons were co-distributed with nitric oxide-generating cells at both levels of the spinal cord, although the double-labeled cells were not observed. In conclusion, the analysis of c-fos expression and NADPH-diaphorase reactivity shows that stimulation of vanilloid receptors in the neck muscles can initiate distinctive neuronal plasticity in the cervical (C1-C8) and lumbar (L1-L7) segments, and confirms the anatomical and functional coupling of both regions during processing of nociceptive signals from the dorsal neck muscles.

  • 93.
    Radovanovic, Sasa
    et al.
    University of Gävle, Belastningsskadecentrum.
    Day, Scott J
    University of Gävle, Belastningsskadecentrum.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    The whole-hand vibration exposure effect on the position sense of the wrist joint2004In: Proceedings of the Fifth International Scientific Conference on Prevention of Work-Related Musculoskeletal Disorders: Zurich, Switzerland, 2004, p. 437-438Conference paper (Other academic)
  • 94.
    Radovanovic, Sasa
    et al.
    University of Gävle, Belastningsskadecentrum.
    Dragasevic, N
    Maric, J
    Milanovic, S
    Ljubisavljevic, Milos
    University of Gävle, Belastningsskadecentrum.
    Kostic, V
    Disturbed cerebellar input affects consecutive movement performance: Comparison of healthy subjects and patients with cerebellar ataxia2005In: The 16th International Congress on Parkinson's Disease and Related Disorders, 2005, p. 245-Conference paper (Refereed)
    Abstract [en]

    Objective

    The cerebellum should be involved in providing temporal computations in motor production. The inability to compute time differences would affect time-related tasks. However, the cerebellar role in proprioception to control precise movement performance is still contradictory. The aim of the study was to investigate the characteristics of performance of the rapid terminal movements in patients with cerebellar ataxia. Ataxia of these patients had been identified as "pure" spinocerebellar ataxia.

    Method

    Movement performance was compared in six patients and six healthy subjects. Movements were performed from the initial to the target position, with the movement length of 40 degree in the elbow flexion. First, motor threshold of the motor cortex was determined. TMS was then applied with the double-cone coil right of the inion, in the two experimental conditions: stimulus was applied with the strength of 5% below the established motor threshold, at the moment of computer generated tone command to start the flexion movement, or stimulus was applied 20 ms before the GO signal, with the same strength. Two additional conditions were also tested: TM stimulus was applied with the strength of 30% above the motor threshold at the moment of movement start, and at 20 ms before movement start.

    Results

    Results point toward extension of the performed movement when stimulus was applied 20 ms before the movement start. Patients show tendency to lengthen their movements, and therefore accuracy of the movements deteriorate. Length of the movements was also prolonged in the conditions where stronger stimulus was applied, but accuracy was less affected with increase in the stimulus strength.

    Conclusion

    Accuracy of the movements was affected when the stimulus was applied in the phase of the movement preparation. Disturbance of the preparatory processes to establish correct movement pattern appear to be important even in the patients with pure cerebellar ataxia.

  • 95.
    Radovanovic, Sasa
    et al.
    University of Gävle, Belastningsskadecentrum.
    Ljubisavljevic, Milos
    University of Gävle, Belastningsskadecentrum.
    Milanovic, S.
    Dragasevic, N.
    Kostic, V.S.
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum.
    The effect of altered sensory afferent input by muscle vibration and exercise on movement performance accuracy in patients with Complex Regional Pain Syndrome (type1)2004In: 8th International Congress of Parkinson's Disease and Movement Disorders: Palazzo dei Congressi Rom, Italy, June 13-17, 2004Conference paper (Refereed)
  • 96.
    Raudsepp, Jaanus
    et al.
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Handgrip maximum force and the visual horizontal-vertical illusion.2005In: Perception, ISSN 0301-0066, E-ISSN 1468-4233, Vol. 34, no 4, p. 421-8Article in journal (Refereed)
    Abstract [en]

    The visual horizontal-vertical illusion (HVI) refers to the tendency to overestimate vertical distances relative to horizontals in both 2-D and 3-D presentations. Although the HVI is evident across a wide range of different stimuli, no general theoretical account fully explains the illusion. Some recent authors have proposed the 'effort' account of HVI, contending that vertical overestimation is mediated by effort assessment of gravitational challenges offered by the stimulus. The theory has been supported by a set of studies showing that the height overestimation of large-scale 3-D objects is inversely related to perceivers' fitness and strength. We explored if the large-scale HVI/strength dependence extends to the evaluation of small-scale 2-D line stimuli, traditionally used in HVI studies. We measured the maximum handgrip strength, and assessed the HVI with a computerised line-adjustment task in thirty-two individuals. Compatible with earlier findings in the context of large-scale 3-D stimuli, a significant negative correlation was found between the strength of the dominant hand and amount of HVI. In addition, the variability of HVI was negatively correlated with maximum grip strength of both hands. The results are discussed with reference to the 'effort' account of HVI.

  • 97.
    Richter, H. O
    et al.
    University of Gävle, Belastningsskadecentrum.
    Andersson, J
    Schneider, H
    Långström, B
    Neuroanatomical correlates of voluntary inhibition of accommodation/vergence under monocular open-loop viewing conditions.2005In: European Journal of Neuroscience, ISSN 0953-816X, E-ISSN 1460-9568, Vol. 21, no 11, p. 3077-3088Article in journal (Refereed)
    Abstract [en]

    The purpose of this work is to identify human neural circuits involved in inhibition of accommodation/vergence by contrasting the cortical functions subservient to negative voluntary accommodation/vergence (NVA) with those evoked by active fixation in darkness (FIX). Five subjects with normal corrected acuity were studied using positron emission tomography and the H O bolus technique. The dominant right eye viewed a laser speckle pattern (633 nm) whose direction and velocity of motion were determined by the refractive state of the eye. The speckle pattern was presented at a distance of 1.8 m (0.55 D). The non-dominant eye was patched. Subjects performed two tasks counterbalanced for order effects: (i) attempted fixation on the remembered target in darkness with the dominant eye open and ‘fixating’; and (ii) voluntary reduction of the laser speckle flow during each alternate 20-s epoch when a convex +2.0 D lens was placed in front of the right eye causing the speckle pattern to move downwards at 3 °/s. Comparison of the condition of NVA with the condition of FIX indicated widespread occipital activation. Decreases in absolute regional cerebral blood flow occurred in the superior parietal cortex (BA 5), frontal cortex (BA 8 and 10) and within the postcentral/precentral gyrus (BA 1/2/3/4) bilaterally where deactivation clusters eclipsed the presumed neck and shoulder areas. Negative accommodation/vergence appears to be driven by a reduction of parasympathetic tone, and has the effect of shutting down brain regions known to be involved in regulating visual search as well as a centrally controlled eye–head–neck–shoulder motor programme responsible for posturing gaze.

  • 98. Roatta, Silvestro
    et al.
    Windhorst, Uwe
    University of Gävle, Belastningsskadecentrum.
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum.
    Lytvynenko, S
    Passatore, Magda
    Effects of sympathetic stimulation on the rhythmical jaw movements produced by electrical stimulation of the cortical masticatory areas of rabbits.2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 162, no 1, p. 14-22Article in journal (Refereed)
    Abstract [en]

    The somatomotor and sympathetic nervous systems are intimately linked. One example is the influence of peripheral sympathetic fibers on the discharge characteristics of muscle spindles. Since muscle spindles play important roles in various motor behaviors, including rhythmic movements, the working hypothesis of this research was that changes in sympathetic outflow to muscle spindles can change rhythmic movement patterns. We tested this hypothesis in the masticatory system of rabbits. Rhythmic jaw movements and EMG activity induced by long-lasting electrical cortical stimulation were powerfully modulated by electrical stimulation of the peripheral stump of the cervical sympathetic nerve (CSN). This modulation manifested itself as a consistent and marked reduction in the excursion of the mandibular movements (often preceded by a transient modest enhancement), which could be attributed mainly to corresponding changes in masseter muscle activity. These changes outlasted the duration of CSN stimulation. In some of the cortically evoked rhythmic jaw movements (CRJMs) changes in masticatory frequency were also observed. When the jaw-closing muscles were subjected to repetitive ramp-and-hold force pulses, the CRMJs changed characteristics. Masseter EMG activity was strongly enhanced and digastric EMG slightly decreased. This change was considerably depressed during CSN stimulation. These effects of CSN stimulation are similar in sign and time course to the depression exerted by sympathetic activity on the jaw-closing muscle spindle discharge. It is suggested that the change in proprioceptive information induced by an increase in sympathetic outflow (a) has important implications even under normal conditions for the control of motor function in states of high sympathetic activity, and (b) is one of the mechanisms responsible for motor impairment under certain pathological conditions such as chronic musculoskeletal head-neck disorders, associated with stress conditions.

  • 99. Roll, Jean-Pierre
    et al.
    Albert, Frédéric
    Ribot-Ciscar, Edith
    Bergenheim, Mikael
    University of Gävle, Belastningsskadecentrum.
    Proprioceptive signature of cursive writing in humans: a multi-population coding.2004In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 157, no 3, p. 359-368Article in journal (Refereed)
    Abstract [en]

    The goal of the present study was to investigate the firing behavior of populations of muscle spindle afferents in all the muscles acting on the ankle while this joint was being subjected to "writing-like" movements. First it was proposed to determine whether the ensemble of muscle spindles give rise to a unique, specific, and reproducible feedback information characterizing each letter, number or short word. Secondly, we analyzed how the proprioceptive feedback on the whole encodes the spatial and temporal characteristics of writing movements using the "vector population model". The unitary activity of 51 primary and secondary muscle spindle afferents was recorded in the tibial and common peroneal nerves at the level of the popliteal fossea, using the microneurographic method. The units recorded from belonged to the tibialis anterior, the extensor digitorum longus, the extensor hallucis longus, the peroneus lateralis, the gastrocnemius-soleus and the tibialis posterior muscles. The "writing-like" movements were randomly imposed at a "natural" velocity via a computer-controlled machine in a two-dimensional space. In general, muscle spindle afferents from any of the six muscles responded according to the tuning properties of the parent muscle, i.e. increasing their discharge rate during the phases where the direction of movement was within the preferred sensory sector of the parent muscle. The whole trajectory of the writing movements was coded in turn by the activity of Ia afferents arising from all the muscles acting on the joint. Both single afferent responses and population responses were found to be highly specific and reproducible with each graphic sign. The complex multi-muscle afferent pattern involved, with its timing and distribution in the muscle space, seems to constitute a true "proprioceptive signature" for each graphic symbol. The ensemble of muscle spindle afferents were therefore found to encode the instantaneous direction and velocity of writing movements remarkably accurately. It was concluded that the proprioceptive feedback from all the muscles with which the moving joint is equipped provides the CNS with highly specific information that might contribute to a graphic sign identification process.

  • 100.
    Sandlund, Jonas
    et al.
    University of Gävle, Belastningsskadecentrum (t.o.m. 051231).
    Djupsjöbacka, Mats
    University of Gävle, Belastningsskadecentrum (t.o.m. 051231).
    Ryhed, B
    Hamberg, Jern
    University of Gävle, Belastningsskadecentrum (t.o.m. 051231).
    Johansson, Håkan
    University of Gävle, Belastningsskadecentrum (t.o.m. 051231).
    Reduced shoulder proprioception in patients with whiplash associated disorders (WAD)2004In: 8th International Federation of Orthopaedic Manipulative Therapists' Conference, Cape Town, South Africa: March 21-26, 2004, 2004Conference paper (Other academic)
    Abstract [en]

    INTRODUCTION: Chronic whiplash associated disorders (WAD) are frequent in medical practice and are presented as a complex picture of neck -and shoulder pain along with numerous other symptoms. However, objective findings at physical examination are usually weak and thus the diagnosis of WAD is mostly based on the medical history and interpretation of personal information. Lately attention has focused on proprioceptive disturbances. Reasonably, vertigo, dizziness and fumbling often reported for WAD patients may be associated with alterations in proprioception. Our lab showed that experimentally induced pain directly impacts muscle spindle activity (MSA) in the muscles primarily affected, as well as in contralateral muscles. Since proprioception is mostly dependent upon MSA, pain originating from the neck region could potentially impair proprioception throughout the upper limbs. To validate proprioceptive testing as a diagnostic tool, the aims of the present study were to investigate: (1) shoulder proprioception, in the ability to reproduce a target position, in WAD patients compared to healthy controls; and (2) possible correlations between the degree of position matching error and subjective rating of health status, disability, self-efficacy and pain. METHODS: Participants were 38 WAD patients and 41 healthy subjects. From a start position of 50 degrees to the sagittal plane, shoulder horizontal-adduction movements of the right glenohumural joint to target positions of 18 and 30 degrees were conducted. The variable error (VE) of the position matching was used to assess the outcome. The patients also completed reports of their general health status (SF-36), disability due to pain (Pain disability index), pain-ratings (VAS) and self-efficacy beliefs (Self efficacy scale). RESULTS: The results showed a significantly higher VE in the WAD-group compared to the controls (p .< 0.001). VE and scores of the self-reports was found to correlate for all the questionnaires used. However, this was true only for the shorter (18 deg) target position. Put together in a step-wise multiple regression model the questionnaires could explain 46 percent of the position matching variance (p < 0.001), but again only when short target positions were focused. DISCUSSION AND CONCLUSION: A reduced ability to reproduce shoulder positions after active displacement implies a disturbance of the sensory motor function of patients with chronic WAD. According to our hypothesis, reduced proprioceptive function of muscle spindles could be responsible for this negative effect on precision and quality of movements. The correlation between position- matching errors and self-reports suggests that this in turn could be reflected in the person's everyday life. Correlations only for shorter target positions indicate that the control of different movement extents may depend on partly different mechanisms. The results may stimulate further research and the possibility of using proprioceptive tests to confirm symptoms and subjective disability in various musculo-skeletal disorders.

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