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- Crenshaw, Albert G., et al.
(author)
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Impact of time pressure and pauses on physiological responses to standardized computer mouse use : a review of three papers with focusing on mechanisms behind computer-related disorders
- 2007
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In: Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; :3, s. 68-75
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Journal article (peer-reviewed)abstract
- This paper reviews three computer mouse studies in our laboratory where our emphasis was on mechanisms behind computer related disorders. Our approach was sequentially (i) to determine validity of a laboratory model of computer mouse use (painting rectangles) for studying musculoskeletal disorders; to use this model (ii) to study time pressure and precision demands on position sense and muscular oxygenation; and (iii) to determine the effect of pauses (active vs passive) on these parameters. (i) Kinematic data for the painting model showed constrained movements of the wrist similar to CAD work; a support for its validity for a real life situation. (ii) Changes in forearm oxygenation were associated with time pressure and precision demands; a potential for insight into the underlying pathophysiological mechanisms. (iii) Increasing trends in oxygenation and blood volume were associated with pauses, especially active; possible explanation for the alleviating effect of discomfort experienced in real life situations when a pause is implemented.
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| 2. |
- Crenshaw, Albert G, et al.
(author)
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Impact of time pressure and pauses on physiological responses to standardized computer mouse use : a review of three papers focusing on mechanisms behind computer-related disorders
- 2007
-
In: Scandinavian Journal of Work, Environment and Health. - Helsinki : Scandinavian journal of work, environment & health. - 0355-3140 .- 1795-990X. ; :Suppl 3, s. 68-75
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Journal article (peer-reviewed)abstract
- This paper reviews three computer mouse studies in our laboratory in which our emphasis was on mechanisms behind computer-related disorders. Our approach was sequentially (i) to determine the validity of a laboratory model for computer mouse use (painting rectangles) for studying musculoskeletal disorders, (ii) to use this model to study time pressure and precision demands on position sense and muscular oxygenation, and (iii) to use this model to determine the effect of pauses (active versus passive) on these parameters. Kinematic data for the painting model showed constrained movements of the wrist similar to that of CAD (computer-aided design) work, a support for its validity for a real-life situation. Changes in forearm oxygenation were associated with time pressure and precision demands, a potential for insight into the underlying pathophysiological mechanisms. Increasing trends in oxygenation and blood volume were associated with pauses, especially active pauses, a possible explanation for the alleviating effect of discomfort experienced in real-life situations when a pause is implemented.
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| 4. |
- Flodgren, Gerd, 1961-, et al.
(author)
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Changes in interstitial noradrenaline, trapezius muscle activity and oxygen saturation during low-load work and recovery
- 2009
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In: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 107:1, s. 31-42
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Journal article (peer-reviewed)abstract
- Both physical as well as mental demands result in an increased activity in the sympathetic nervous system (SNS) with changes in blood-pressure and heart-rate. Through local release of catecholamines, e.g. noradrenaline (NAd) SNS exerts various actions at the muscle level. The aims of this study were to investigate the effects of low-load repetitive work alone and in combination with mental demands on local muscle interstitial noradrenaline concentration [NAd]i, muscle activity and oxygenation, assessed with microdialysis, surface electromyography, and near-infrared spectroscopy, respectively. Healthy females (n = 15) were exposed to (1) 30 min repetitive work (RW) and (2) 30 min repetitive work with superimposed mental load (RWML) on two different occasions. Muscle [NAd]i and muscle activity increased significantly in response to RW, but did not increase further during RWML. For RW, [NAd]i was found to be inversely correlated to muscle activity. Oxygenation decreased significantly during work, independently of occasion. Our findings indicate that low-load work causes significantly increased trapezius muscle [NAd]i in healthy females, and short periods of superimposed mental load do not add to this increase and further, that both muscle activity and oxygenation were unaffected by the superimposed mental load.
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| 5. |
- Flodgren, Gerd, et al.
(author)
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Combining microdialysis and near infrared spectroscopy for studying effects of low-load repetitive work on the intramuscular chemistry in trapezius myalgia
- 2010
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In: Journal of Biomedicine and Biotechnology. - : Hindawi Limited. - 1110-7243 .- 1110-7251. ; 2010
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Journal article (peer-reviewed)abstract
- Epidemiological research provides strong evidence for a link between repetitive work (RW) and the development of chronic trapezius myalgia (TM). The aims were to further elucidate if an accumulation of sensitising substances or impaired oxygenation is evident in painful muscles during RW. Females with TM (n=14) were studied during rest, 30 min RW and 60 min recovery. Microdialysate samples were obtained to determine changes in [glutamate], [PGE2], [lactate], and [pyruvate] relative to work. Muscle oxygenation (%StO2) was assessed using near-infrared spectroscopy. During work all investigated substances, except PGE2, increased significantly: [glutamate] (54%, P<0.0001), [lactate] (26%, P<0.005), [pyruvate] (19%, P<0.0001), while the %StO2 decreased (P<0.05). During recovery [PGE2] decreased (P<0.005), [lactate] remained increased (P<0.001), [pyruvate] increased progressively (P<0.0001), and %StO2 had returned to baseline. Changes in substance concentrations and oxygenation in response to work indicate normal increase in metabolism but no ongoing inflammation in subjects withTM.
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| 6. |
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| 7. |
- Flodgren, Gerd, 1961-
(author)
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Effects of low-load repetitive work and mental load on sensitising substances and metabolism in the trapezius muscle
- 2007
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Doctoral thesis (other academic/artistic)abstract
- Low-load repetitive work (LLRW) and mental load are important risk factors for the development of workrelated muscle pain. The link between these risk factors and the development of pain is still not understood, but stimulation of chemo-sensitive receptors in the muscle probably plays an important role. It has been suggested that sensitising substances may accumulate in the muscle during LLRW, especially when combined with mental load. The overall purpose of this thesis was to try to shed some light on the effects of LLRW on the concentration of sensitising substances (glutamate, prostaglandin E2 (PGE2), norepinephrine (NE)) and on metabolism (lactate, pyruvate and oxygenation) in the trapezius muscle of healthy controls (CON) and subjects with trapezius myalgia (TM). A first step was to investigate whether females with TM exhibit higher absolute concentrations of glutamate and PGE2 in the affected muscle during rest. Using Microdialysis (MD) females with TM and asymptomatic controls were studied during four hours of rest. [Glutamate] and [PGE2] during rest did not differ between groups. A second step was to investigate, in a simulated occupational setting, the effects of LLRW on the concentration of sensitising substances and metabolism in the trapezius muscle of TM and CON, and whether increased work duration resulted in a progressive effect. Asymptomatic females were studied during baseline rest, 30 versus 60 min work and recovery, using MD and near infrared spectroscopy (NIRS). Subjects with TM were studied during baseline rest, 30 min work and recovery. [Glutamate] and [lactate] increased in response to work, but not progressively with increased work duration. [Glutamate] was at all time points significantly lower in TM. [PGE2]and oxygenation remained unchanged during work for CON, while for TM oxygenation decreased significantly during work. In TM [pyruvate] increased during both work and recovery, and a significant interaction between groups was found for [pyruvate] during recovery; while moderately increased in CON it increased progressively in TM. The effects of LLRW with and without superimposed mental load on intramuscular [NE], muscle activity and oxygen saturation in the trapezius were also investigated and compared. Using MD, electromyography and NIRS, healthy females were studied on two occasions; during 30 min LLRW and during 30 min LLRW with superimposed mental load. During work [NE], and muscle activity, were increased, while oxygenation decreased, but no differences between occasions. However, recovery of [NE] to baseline was slower after LLRW with superimposed mental load. The findings of the present thesis suggest: (i) no inflammation, or increased interstitial [glutamate] in TM; (ii) LLRW causes an increased anaerobic metabolism in both TM and CON; (iii) no effect of work duration was found; (iv) a significant difference in the effects of LLRW on the interstitial milieu of the trapezius muscle in TM as compared to CON; (v) LLRW causes a significant increase in [NE], but superimposed mental load does not cause a further increase; (vi) LLRW with a superimposed mental load may result in a slower recovery to baseline [NE] as compared with LLRW alone.
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