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Mikael Forsman - One of the best experts on this subject based on the ideXlab platform.
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effect of ciliary Muscle contraction force on Trapezius Muscle activity during computer mouse work
European Journal of Applied Physiology, 2019Co-Authors: Dmitry Domkin, Mikael Forsman, Hans O RichterAbstract:The present study aimed to identify whether or not an increase in ciliary-Muscle contraction force, when the eye-lens is adjusted for viewing at a near distance, results in an increase in Trapezius Muscle activity, while performing a natural work task. Twelve participants, ranging in age from 21 to 32 years, performed a computer-mouse work task during free gaze conditions. A moving visual target was tracked with a computer mouse on a screen placed at two different distances from the eyes, 25 cm and 50 cm. Tracking performance, eye accommodation, and bilateral Trapezius Muscle activity were measured continuously. Ciliary-Muscle contraction force was computed according to a formula which takes into account the age-dependent, non-linear relationship between the contraction force of the ciliary Muscle and the produced level of eye accommodation. Generalized estimating equations analyses were performed. On the dominant hand side and for the nearest screen distance, there was a significant effect of ciliary-Muscle contraction force on the Trapezius Muscle activity (p 0.05). The results support the hypothesis that high visual demands, during computer mouse work, increase ciliary Muscle contraction force and contribute to a raise of the sustained level of Trapezius Muscle activity. The current study specifically clarifies the validity of the relationship between ciliary-Muscle contraction force and Trapezius Muscle activity and demonstrates that this relationship is not due to a general personality trait. We conclude that a high level of ciliary Muscle contraction force can contribute to a development of musculoskeletal complaints in the neck–shoulder area.
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Ciliary Muscle contraction force and Trapezius Muscle activity during manual tracking of a moving visual target.
Journal of Electromyography and Kinesiology, 2015Co-Authors: Dmitry Domkin, Mikael Forsman, Hans O RichterAbstract:Abstract Previous studies have shown an association of visual demands during near work and increased activity of the Trapezius Muscle. Those studies were conducted under stationary postural conditions with fixed gaze and artificial visual load. The present study investigated the relationship between ciliary Muscle contraction force and Trapezius Muscle activity across individuals during performance of a natural dynamic motor task under free gaze conditions. Participants ( N =11) tracked a moving visual target with a digital pen on a computer screen. Tracking performance, eye refraction and Trapezius Muscle activity were continuously measured. Ciliary Muscle contraction force was computed from eye accommodative response. There was a significant Pearson correlation between ciliary Muscle contraction force and Trapezius Muscle activity on the tracking side (0.78, p p
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temporal co variation between eye lens accommodation and Trapezius Muscle activity during a dynamic near far visual task
PLOS ONE, 2015Co-Authors: Camilla Zetterberg, Hans O Richter, Mikael ForsmanAbstract:Near work is associated with increased activity in the neck and shoulder Muscles, but the underlying mechanism is still unknown. This study was designed to determine whether a dynamic change in focus, alternating between a nearby and a more distant visual target, produces a direct parallel change in Trapezius Muscle activity. Fourteen healthy controls and 12 patients with a history of visual and neck/shoulder symptoms performed a Near-Far visual task under three different viewing conditions; one neutral condition with no trial lenses, one condition with negative trial lenses to create increased accommodation, and one condition with positive trial lenses to create decreased accommodation. Eye lens accommodation and Trapezius Muscle activity were continuously recorded. The Trapezius Muscle activity was significantly higher during Near than during Far focusing periods for both groups within the neutral viewing condition, and there was a significant co-variation in time between accommodation and Trapezius Muscle activity within the neutral and positive viewing conditions for the control group. In conclusion, these results reveal a connection between Near focusing and increased Muscle activity during dynamic changes in focus between a nearby and a far target. A direct link, from the accommodation/vergence system to the Trapezius Muscles cannot be ruled out, but the connection may also be explained by an increased need for eye-neck (head) stabilization when focusing on a nearby target as compared to a more distant target.
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Trapezius Muscle activity increases during near work activity regardless of accommodation vergence demand level
European Journal of Applied Physiology, 2015Co-Authors: Hans O Richter, Camilla Zetterberg, Mikael ForsmanAbstract:Aim To investigate if Trapezius Muscle activity increases over time during visually demanding near work.
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effects of visually demanding near work on Trapezius Muscle activity
Journal of Electromyography and Kinesiology, 2013Co-Authors: Camilla Zetterberg, Mikael Forsman, Hans O RichterAbstract:Poor visual ergonomics is associated with visual and neck/shoulder discomfort, but the relation between visual demands and neck/shoulder Muscle activity is unclear. The aims of this study were to investigate whether Trapezius Muscle activity was affected by: (i) eye-lens accommodation; (ii) incongruence between accommodation and convergence; and (iii) presence of neck/shoulder discomfort. Sixty-six participants (33 controls and 33 with neck pain) performed visually demanding near work under four different trial-lens conditions. Results showed that eye-lens accommodation per se did not affect Trapezius Muscle activity significantly. However, when incongruence between accommodation and convergence was present, a significant positive relationship between eye-lens accommodation and Trapezius Muscle activity was found. There were no significant group-differences. It was concluded that incongruence between accommodation and convergence is an important factor in the relation between visually demanding near work and Trapezius Muscle activity. The relatively low demands on accommodation and convergence in the present study imply that visually demanding near work may contribute to increased Muscle activity, and over time to the development of near work related neck/shoulder discomfort.
Hans O Richter - One of the best experts on this subject based on the ideXlab platform.
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effect of ciliary Muscle contraction force on Trapezius Muscle activity during computer mouse work
European Journal of Applied Physiology, 2019Co-Authors: Dmitry Domkin, Mikael Forsman, Hans O RichterAbstract:The present study aimed to identify whether or not an increase in ciliary-Muscle contraction force, when the eye-lens is adjusted for viewing at a near distance, results in an increase in Trapezius Muscle activity, while performing a natural work task. Twelve participants, ranging in age from 21 to 32 years, performed a computer-mouse work task during free gaze conditions. A moving visual target was tracked with a computer mouse on a screen placed at two different distances from the eyes, 25 cm and 50 cm. Tracking performance, eye accommodation, and bilateral Trapezius Muscle activity were measured continuously. Ciliary-Muscle contraction force was computed according to a formula which takes into account the age-dependent, non-linear relationship between the contraction force of the ciliary Muscle and the produced level of eye accommodation. Generalized estimating equations analyses were performed. On the dominant hand side and for the nearest screen distance, there was a significant effect of ciliary-Muscle contraction force on the Trapezius Muscle activity (p 0.05). The results support the hypothesis that high visual demands, during computer mouse work, increase ciliary Muscle contraction force and contribute to a raise of the sustained level of Trapezius Muscle activity. The current study specifically clarifies the validity of the relationship between ciliary-Muscle contraction force and Trapezius Muscle activity and demonstrates that this relationship is not due to a general personality trait. We conclude that a high level of ciliary Muscle contraction force can contribute to a development of musculoskeletal complaints in the neck–shoulder area.
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Ciliary Muscle contraction force and Trapezius Muscle activity during manual tracking of a moving visual target.
Journal of Electromyography and Kinesiology, 2015Co-Authors: Dmitry Domkin, Mikael Forsman, Hans O RichterAbstract:Abstract Previous studies have shown an association of visual demands during near work and increased activity of the Trapezius Muscle. Those studies were conducted under stationary postural conditions with fixed gaze and artificial visual load. The present study investigated the relationship between ciliary Muscle contraction force and Trapezius Muscle activity across individuals during performance of a natural dynamic motor task under free gaze conditions. Participants ( N =11) tracked a moving visual target with a digital pen on a computer screen. Tracking performance, eye refraction and Trapezius Muscle activity were continuously measured. Ciliary Muscle contraction force was computed from eye accommodative response. There was a significant Pearson correlation between ciliary Muscle contraction force and Trapezius Muscle activity on the tracking side (0.78, p p
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temporal co variation between eye lens accommodation and Trapezius Muscle activity during a dynamic near far visual task
PLOS ONE, 2015Co-Authors: Camilla Zetterberg, Hans O Richter, Mikael ForsmanAbstract:Near work is associated with increased activity in the neck and shoulder Muscles, but the underlying mechanism is still unknown. This study was designed to determine whether a dynamic change in focus, alternating between a nearby and a more distant visual target, produces a direct parallel change in Trapezius Muscle activity. Fourteen healthy controls and 12 patients with a history of visual and neck/shoulder symptoms performed a Near-Far visual task under three different viewing conditions; one neutral condition with no trial lenses, one condition with negative trial lenses to create increased accommodation, and one condition with positive trial lenses to create decreased accommodation. Eye lens accommodation and Trapezius Muscle activity were continuously recorded. The Trapezius Muscle activity was significantly higher during Near than during Far focusing periods for both groups within the neutral viewing condition, and there was a significant co-variation in time between accommodation and Trapezius Muscle activity within the neutral and positive viewing conditions for the control group. In conclusion, these results reveal a connection between Near focusing and increased Muscle activity during dynamic changes in focus between a nearby and a far target. A direct link, from the accommodation/vergence system to the Trapezius Muscles cannot be ruled out, but the connection may also be explained by an increased need for eye-neck (head) stabilization when focusing on a nearby target as compared to a more distant target.
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Trapezius Muscle activity increases during near work activity regardless of accommodation vergence demand level
European Journal of Applied Physiology, 2015Co-Authors: Hans O Richter, Camilla Zetterberg, Mikael ForsmanAbstract:Aim To investigate if Trapezius Muscle activity increases over time during visually demanding near work.
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effects of visually demanding near work on Trapezius Muscle activity
Journal of Electromyography and Kinesiology, 2013Co-Authors: Camilla Zetterberg, Mikael Forsman, Hans O RichterAbstract:Poor visual ergonomics is associated with visual and neck/shoulder discomfort, but the relation between visual demands and neck/shoulder Muscle activity is unclear. The aims of this study were to investigate whether Trapezius Muscle activity was affected by: (i) eye-lens accommodation; (ii) incongruence between accommodation and convergence; and (iii) presence of neck/shoulder discomfort. Sixty-six participants (33 controls and 33 with neck pain) performed visually demanding near work under four different trial-lens conditions. Results showed that eye-lens accommodation per se did not affect Trapezius Muscle activity significantly. However, when incongruence between accommodation and convergence was present, a significant positive relationship between eye-lens accommodation and Trapezius Muscle activity was found. There were no significant group-differences. It was concluded that incongruence between accommodation and convergence is an important factor in the relation between visually demanding near work and Trapezius Muscle activity. The relatively low demands on accommodation and convergence in the present study imply that visually demanding near work may contribute to increased Muscle activity, and over time to the development of near work related neck/shoulder discomfort.
Camilla Zetterberg - One of the best experts on this subject based on the ideXlab platform.
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Trapezius Muscle activity increases during near work activity regardless of accommodation/vergence demand level
European Journal of Applied Physiology, 2015Co-Authors: H. O. Richter, Camilla Zetterberg, M. ForsmanAbstract:Aim To investigate if Trapezius Muscle activity increases over time during visually demanding near work. Methods The vision task consisted of sustained focusing on a contrast-varying black and white Gabor grating. Sixty-six participants with a median age of 38 (range 19–47) fixated the grating from a distance of 65 cm (1.5 D) during four counterbalanced 7-min periods: binocularly through −3.5 D lenses, and monocularly through −3.5 D, 0 D and +3.5 D. Accommodation, heart rate variability and Trapezius Muscle activity were recorded in parallel. Results General estimating equation analyses showed that Trapezius Muscle activity increased significantly over time in all four lens conditions. A concurrent effect of accommodation response on Trapezius Muscle activity was observed with the minus lenses irrespective of whether incongruence between accommodation and convergence was present or not. Conclusions Trapezius Muscle activity increased significantly over time during the near work task. The increase in Muscle activity over time may be caused by an increased need of mental effort and visual attention to maintain performance during the visual tasks to counteract mental fatigue.
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temporal co variation between eye lens accommodation and Trapezius Muscle activity during a dynamic near far visual task
PLOS ONE, 2015Co-Authors: Camilla Zetterberg, Hans O Richter, Mikael ForsmanAbstract:Near work is associated with increased activity in the neck and shoulder Muscles, but the underlying mechanism is still unknown. This study was designed to determine whether a dynamic change in focus, alternating between a nearby and a more distant visual target, produces a direct parallel change in Trapezius Muscle activity. Fourteen healthy controls and 12 patients with a history of visual and neck/shoulder symptoms performed a Near-Far visual task under three different viewing conditions; one neutral condition with no trial lenses, one condition with negative trial lenses to create increased accommodation, and one condition with positive trial lenses to create decreased accommodation. Eye lens accommodation and Trapezius Muscle activity were continuously recorded. The Trapezius Muscle activity was significantly higher during Near than during Far focusing periods for both groups within the neutral viewing condition, and there was a significant co-variation in time between accommodation and Trapezius Muscle activity within the neutral and positive viewing conditions for the control group. In conclusion, these results reveal a connection between Near focusing and increased Muscle activity during dynamic changes in focus between a nearby and a far target. A direct link, from the accommodation/vergence system to the Trapezius Muscles cannot be ruled out, but the connection may also be explained by an increased need for eye-neck (head) stabilization when focusing on a nearby target as compared to a more distant target.
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Trapezius Muscle activity increases during near work activity regardless of accommodation vergence demand level
European Journal of Applied Physiology, 2015Co-Authors: Hans O Richter, Camilla Zetterberg, Mikael ForsmanAbstract:Aim To investigate if Trapezius Muscle activity increases over time during visually demanding near work.
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effects of visually demanding near work on Trapezius Muscle activity
Journal of Electromyography and Kinesiology, 2013Co-Authors: Camilla Zetterberg, Mikael Forsman, Hans O RichterAbstract:Poor visual ergonomics is associated with visual and neck/shoulder discomfort, but the relation between visual demands and neck/shoulder Muscle activity is unclear. The aims of this study were to investigate whether Trapezius Muscle activity was affected by: (i) eye-lens accommodation; (ii) incongruence between accommodation and convergence; and (iii) presence of neck/shoulder discomfort. Sixty-six participants (33 controls and 33 with neck pain) performed visually demanding near work under four different trial-lens conditions. Results showed that eye-lens accommodation per se did not affect Trapezius Muscle activity significantly. However, when incongruence between accommodation and convergence was present, a significant positive relationship between eye-lens accommodation and Trapezius Muscle activity was found. There were no significant group-differences. It was concluded that incongruence between accommodation and convergence is an important factor in the relation between visually demanding near work and Trapezius Muscle activity. The relatively low demands on accommodation and convergence in the present study imply that visually demanding near work may contribute to increased Muscle activity, and over time to the development of near work related neck/shoulder discomfort.
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HCI (23) - Temporal dependence of Trapezius Muscle activation during sustained eye-lens accommodation at near
Digital Human Modeling and Applications in Health Safety Ergonomics and Risk Management. Human Body Modeling and Ergonomics, 2013Co-Authors: Hans O Richter, Camilla Zetterberg, Mikael ForsmanAbstract:In this experimental study different levels of oculomotor load were induced via optical trial lenses. The aim was to investigate the temporal dependence of a moderate visual load on Trapezius Muscle activity. Trapezius Muscle activity was measured with bipolar surface electromyography (EMG). Sixty-six subjects with a median age of 36 (range 19---47, std 8) viewed a black and white Gabor grating (5 c/deg) through 0 D, and -3.5 D lenses, in periods of 7-min. An auto refractor was used to continuously sample data on eye-lens accommodation during the vision tasks. Response-diopters were used as a dichotomous high/low accommodation grouping variable. For these groups EMG amplitudes during minutes 1-7 per each lens trial were studied separately with Generalized Estimating Equations (GEE). The analysis results showed significant increases in Trapezius Muscle activity over time for both viewing conditions. For the binocular -3.5 D condition response-diopters gave a significant positive contribution to the EMG amplitude. The results indicate that sustained eye-lens accommodation at near, during ergonomically unfavorable viewing conditions, may increase the risk for Trapezius Muscle myalgia.
N. Bedforth - One of the best experts on this subject based on the ideXlab platform.
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ultrasound guided spinal accessory nerve blockade in the diagnosis and management of Trapezius Muscle related myofascial pain
Anaesthesia, 2011Co-Authors: P. Townsley, A. Ravenscroft, N. BedforthAbstract:Summary We report the first description of ultrasound-guided spinal accessory nerve blockade using single-shot and subsequently continuous infusion (via a perineural catheter) local anaesthetic techniques, for the diagnosis and treatment of myofascial pain affecting the Trapezius Muscle. A 38-year-old man presented with a two-year history of incapacitating left suprascapular pain after a fall onto his outstretched hand. The history and clinical examination was suggestive of myofascial pain affecting the Trapezius Muscle. This had been unresponsive to pharmacological therapy, physiotherapy or suprascapular nerve blockade. Following identification of the spinal accessory nerve in the posterior triangle of the neck, we performed ultrasound-guided nerve blocks, first using a single injection of local anaesthetic and subsequently using a continuous infusion via a perineural catheter, to block the nerve and temporarily relieve the patient’s pain. We have demonstrated that the spinal accessory nerve is identifiable in the posterior triangle of the neck and can be blocked successfully using ultrasound guidance. This technique can aid the diagnosis and treatment of myofascial pain originating from the Trapezius Muscle.
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Ultrasound‐guided spinal accessory nerve blockade in the diagnosis and management of Trapezius Muscle‐related myofascial pain
Anaesthesia, 2011Co-Authors: P. Townsley, A. Ravenscroft, N. BedforthAbstract:Summary We report the first description of ultrasound-guided spinal accessory nerve blockade using single-shot and subsequently continuous infusion (via a perineural catheter) local anaesthetic techniques, for the diagnosis and treatment of myofascial pain affecting the Trapezius Muscle. A 38-year-old man presented with a two-year history of incapacitating left suprascapular pain after a fall onto his outstretched hand. The history and clinical examination was suggestive of myofascial pain affecting the Trapezius Muscle. This had been unresponsive to pharmacological therapy, physiotherapy or suprascapular nerve blockade. Following identification of the spinal accessory nerve in the posterior triangle of the neck, we performed ultrasound-guided nerve blocks, first using a single injection of local anaesthetic and subsequently using a continuous infusion via a perineural catheter, to block the nerve and temporarily relieve the patient’s pain. We have demonstrated that the spinal accessory nerve is identifiable in the posterior triangle of the neck and can be blocked successfully using ultrasound guidance. This technique can aid the diagnosis and treatment of myofascial pain originating from the Trapezius Muscle.
Dario Farina - One of the best experts on this subject based on the ideXlab platform.
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adaptations of upper Trapezius Muscle activity during sustained contractions in women with fibromyalgia
Journal of Electromyography and Kinesiology, 2010Co-Authors: Deborah Falla, Helle Vibeke Andersen, Bente Danneskioldsamsoe, Lars Arendtnielsen, Dario FarinaAbstract:Abstract The study compared the distribution of electromyographic (EMG) signal amplitude in the upper Trapezius Muscle in 10 women with fibromyalgia and in 10 healthy women before and after experimentally-induced Muscle pain. Surface EMG signals were recorded over the right upper Trapezius Muscle with a 10 × 5 grid of electrodes during 90° shoulder abduction sustained for 60 s. The control subjects repeated the abduction task following injections of isotonic and hypertonic (painful) saline into the upper Trapezius Muscle. The EMG amplitude was computed for each electrode pair and provided a topographical map of the distribution of Muscle activity. The pain level rated by the patients at the beginning of the sustained contraction was 5.9 ± 1.5. The peak pain intensity for the control group following the injection of hypertonic saline was 6.0 ± 1.6. During the sustained contractions, the EMG amplitude increased relatively more in the cranial than caudal region of the upper Trapezius Muscle for the control subjects (shift in the distribution of EMG amplitude: 2.3 ± 1.3 mm; P
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gender specific adaptations of upper Trapezius Muscle activity to acute nociceptive stimulation
Pain, 2008Co-Authors: Deborah Falla, Lars Arendtnielsen, Dario FarinaAbstract:Abstract This study examined gender differences in the effect of experimental Muscle pain on changes in the relative activation of regions of the upper Trapezius Muscle during a sustained contraction. Surface electromyographic (EMG) signals were recorded from multiple locations over the upper Trapezius Muscle with a 10 × 5 grid of electrodes from nine women and nine men during 90° shoulder abduction sustained for 60 s. Measurements were performed before and after the injection of 0.4 ml hypertonic (painful) and isotonic (control) saline into the cranial region of the upper Trapezius Muscle. The EMG root mean square (RMS) was computed for each location of the grid to form a map of the EMG amplitude distribution. The peak pain intensity following the injection of hypertonic saline was greater for women (numerical rating scale 0–10: women 6.0 ± 2.1, men 4.2 ± 0.9; P
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spatial dependency of Trapezius Muscle activity during repetitive shoulder flexion
Journal of Electromyography and Kinesiology, 2007Co-Authors: Deborah Falla, Dario Farina, Thomas GravennielsenAbstract:Abstract The purpose of this study was to explore changes in spatial Muscle activation within the three divisions of the Trapezius Muscle during a dynamic, cyclic task of the upper limb. Surface EMG signals were detected from thirteen healthy subjects from the upper, middle and lower divisions of the Trapezius Muscle at multiple electrode sites in the cephalad-caudal direction during a repetitive shoulder flexion task. Initial values and rate of change of average rectified value (ARV) and of instantaneous mean power spectral frequency (iMNF) were estimated at 45°, 90° and 120° of shoulder flexion throughout the 5-min task. The location of the electrodes had a significant effect on initial EMG ARV for both the upper and middle division of the Trapezius Muscle ( P P P
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experimental Muscle pain results in reorganization of coordination among Trapezius Muscle subdivisions during repetitive shoulder flexion
Experimental Brain Research, 2007Co-Authors: Deborah Falla, Dario Farina, Thomas GravennielsenAbstract:The aim of the study was to examine the effect of experimental unilateral upper Trapezius Muscle pain on the relative activation of Trapezius Muscle subdivisions bilaterally during repetitive movement of the upper limb. Surface EMG signals were detected from nine healthy subjects from the upper, middle and lower divisions of Trapezius during a repetitive bilateral shoulder flexion task. Measurements were performed before and after injection of 0.5 ml hypertonic (pain condition) and isotonic (control) saline into the upper division of the right Trapezius Muscle in two experimental sessions. On the painful side, upper Trapezius showed decreased EMG amplitude (average rectified value, ARV) and lower Trapezius increased ARV throughout the entire task following the injection of hypertonic saline (40.0 ± 22.2 vs. 26.0 ± 17.4 μV, and 12.5 ± 7.6 vs. 25.6 ± 14.8 μV, respectively, at the beginning of the contraction). On the side contralateral to pain, greater estimates of ARV were identified for the upper division of Trapezius as the task progressed (37.4 ± 20.2 vs. 52.7 ± 28.4 μV, at the end of the contraction). Muscle fiber conduction velocity did not change with pain in all three divisions of the right Trapezius Muscle. The results suggest that local elicitation of nociceptive afferents in the upper division of the Trapezius induces reorganization in the coordinated activity of the three subdivisions of the Trapezius in repetitive dynamic tasks.
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standardising surface electromyogram recordings for assessment of activity and fatigue in the human upper Trapezius Muscle
European Journal of Applied Physiology, 2002Co-Authors: Dario Farina, Thomas Gravennielsen, Pascal Madeleine, Roberto Merletti, Lars ArendtnielsenAbstract:The objectives of this work were to determine optimal surface electromyogram (EMG) electrode locations, and inter-electrode distance (IED), when assessing activity and fatigue in the human upper Trapezius Muscle. Surface EMG signals were recorded from the upper Trapezius Muscle of 11 healthy male subjects using a linear array of 16 surface electrodes. Five arm positions were investigated (arms at the side of the body, 45° and 90° flexion, 45° and 90° abduction). Fatiguing (1 kg hand load held for 3 min) and non-fatiguing (no load, 0.5 kg and 1 kg hand load held for 3 s) contractions were made. The variabilities of the average rectified value, root mean square, mean and median power spectral frequency and slope over time of these parameters as functions of electrode location and IED (from 5 mm over a range of 35 mm in steps of 5 mm) were quantitatively evaluated. A criterion for selecting the optimal electrode position was applied. This criterion indicated an optimal location measured from the acromion (38% of the distance from the lateral edge of acromion to the spine of the seventh cervical vertebra) which was statistically the same for all the EMG descriptors, arm positions and IED investigated. Finally, it was found that both EMG variables and indexes of Muscle fatigue depended on IED which should thus be properly standardised. On the basis of the sensitivity of the EMG descriptors to electrode location and cross-talk reduction, an IED of 20 mm is suggested when a global analysis of activity in the upper Trapezius Muscle is made using a single pair of electrodes. This study emphasises that a surface EMG analysis of the upper Trapezius Muscle, following a proper placement of the electrodes and selection of IED, can give reliable indications of Muscle activity and fatigue. Data on the myoelectric manifestations of Muscle fatigue of the upper Trapezius Muscle are provided for the optimal electrode location.
