Abstract
Work-related upper extremity disorders (WRUEDs) that result from keyboarding tasks are prevalent and costly. Although the precise mechanisms causing the disorder are not yet fully understood, several risk factors have been proposed. These include the repetitive nature of the motor task and the associated sustained static working postures, but also more psychological factors such as mental load. Epidemiological surveys have shown that WRUEDs are more prone to develop in the postural muscles of the neck/shoulder area than in the executive muscles controlling the hand. The present study investigated whether the activation patterns of these two muscle types are differentially affected by an additional mental load during the performance of a repetitive tapping task. Participants tapped various keying patterns with their dominant index finger at two prescribed tempi. Mental load was manipulated by means of an auditory short-term memory task. We recorded the EMG activity of two neck/shoulder muscles (trapezius and deltoid), two upper arm muscles (biceps and triceps), and four forearm muscles (flexor digitorum superficialis, extensor digitorum, extensor carpi radialis longus and extensor carpi ulnaris) and analyzed the kinematics and impact forces of the index finger. The results confirmed that the upper limb has two functions. Specifically, activity of the executive distal musculature was increased during tapping at the higher pace, while the activity of the postural upper limb musculature was elevated due to the memory task. We argue that continuously increased muscular activity can lead to fatigue and thus eventually cause musculoskeletal complaints. The results are discussed with respect to biomechanical adaptation strategies that deal with the consequences of increased noise in the neuromotor system due to enhanced mental processing.
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Notes
Work related upper extremity disorder (WRUED) is one of the prevalent terms used to indicate this group of musculoskeletal disorders. Other more or less homonymous terms used are: Repetitive Strain Injury (RSI), Cumulative Trauma Disorder (CTD), Work Related Upper Limb Disorder (WRULD), Occupational Overuse Syndrome (OOS), Occupational Cervicobrachial Disorder (OCD), Upper Limb Disorder (ULD), and Workrelated Musculoskeletal Disorder (WMSD)
Assuming an alpha of 0.05, the odds that three consecutive bins hold a type I error is 0.05 * 0.05 * 0.05 = 0.000125 or 1 in 8000 cases. We tested 100 bins, the chance of a Type I error being 100 * 0.000125 = 0.0125, which is well below the initial alpha level of 0.05 (see also Van Schie et al. 2003).
References
Bansevicius D, Sjaastad O (1996) Cervicogenic headache: the influence of mental load on pain level and EMG of shoulder-neck and facial muscles. Headache 36:372–378
Bernstein N (1967) The co-ordination and regulation of movement. Pergamon Press, London
Birch L, Juul-Kristensen B, Jensen C, Finsen L, Christensen H (2000) Acute response to precision, time pressure and mental demand during simulated computer work. Scandinavian Journal of Work and Environmental Health 26:299–305
Blatter BM, Bongers PM, Kraam KO, Dhondt S (2000) RSI klachten in de werkende populatie. De mate van voorkomen en de relatie met beeldschermwerk, muisgebruik en andere ICT-gerelateerde factoren. [RSI complaints in the working population. Prevalence and the relation with visual dispay work, mouse use and other ICT-related factors]. Hoofddorp: TNO Arbeid
Bloemsaat JG, Ruijgrok JM, Van Galen GP (2004) Patients suffering from nonspecific work-related upper extremity disorders exhibit insufficient movement strategies. Acta Psychol(Amst) 115:17–33
Bongers PM, De Winter CR, Kompier MAJ, Hildebrandt VH (1993) Psychosocial factors at work and musculoskeletal disease. Scandinavian Journal of Work Environment & Health 19:297–312
Bongers PM, Kremer AM, Ter Laak J (2002) Are psychosocial factors, risk factors for symptoms and signs of the shoulder, elbow, or hand/wrist?: A review of the epidemiological literature. American Journal of Industrial Medicine 41:315–342
Bosga J, Meulenbroek RG, Swinnen SP (2003) Stability of inter-joint coordination during circle drawing: effects of shoulder-joint articular properties. Hum Mov Sci 22:297–320
Danion F, Gallea C (2004) The relation between force magnitude, force steadiness, and muscle co-contraction in the thumb during precision grip. Neuroscience Letters 368:176–180
Dennerlein JT, Mote CD, Rempel DM (1998) Control strategies for finger movement during touch typing - The role of the extrinsic muscles during a keystroke. Experimental Brain Research 121:1–6
Fallentin N, Sidenius B, Jorgensen K (1985) Blood-pressure, heart-rate and emg in low-level static contractions. Acta Physiologica Scandinavica 125:265–275
Finsen L, Sogaard K, Jensen C, Borg V, Christensen H (2001) Muscle activity and cardiovascular response during computer-mouse work with and without memory demands. Ergonomics 44:1312–1329
Franklin DW, Burdet E, Osu R, Kawato M, Milner TE (2003) Functional significance of stiffness in adaptation of multijoint arm movements to stable and unstable dynamics. Experimental Brain Research 151:145–157
Gribble PL, Mullin LI, Cothros N, Mattar A (2003) Role of cocontraction in arm movement accuracy. Journal of Neurophysiology 89:2396–2405
Hamilton AFD, Jones KE, Wolpert DM (2004) The scaling of motor noise with muscle strength and motor unit number in humans. Experimental Brain Research 157:417–430
Harris CM, Wolpert DM (1998) Signal-dependent noise determines motor planning. Nature 394:780–784
Haufler AJ, Feuerstein M, Huang GD (2000) Job stress, upper extremity pain and functional limitations in symptomatic computer users. American Journal of Industrial Medicine 38:507–515
Higuchi T, Imanaka K, Hatayama T (2002) Freezing degrees of freedom under stress: Kinematic evidence of constrained movement strategies. Human Movement Science 21:831–846
Hogan N (1984) Adaptive-control of mechanical impedance by coactivation of antagonist muscles. Ieee Transactions on Automatic Control 29:681–690
Johansson H, Sojka P (1991) Pathophysiological mechanisms involved in genesis and spread of muscular tension in occupational muscle pain and in chronic musculoskeletal pain syndromes - A hypothesis. Medical Hypotheses 35:196–203
Kim YJ, Kuboki T, Tsukiyama Y, Koyano K, Clark GT (1999) Haemodynamic changes in human masseter and temporalis muscles induced by different levels of isometric contraction. Archives of Oral Biology 44:641–650
Lacquaniti F, Maiolo C (1987) Anticipatory and reflex coactivation of antagonist muscles in catching. Brain Research 406:373–378
Laursen B, Jensen BR, Sjogaard G (1998) Effect of speed and precision demands on human shoulder muscle electromyography during a repetitive task. European Journal of Applied Physiology 78:544–548
Laursen B, Jensen BR, Garde AH, Jorgensen AH (2002) Effect of mental and physical demands on muscular activity during the use of a computer mouse and a keyboard. Scandinavian Journal of Work Environment & Health 28:215–221
Lundberg U, Kadefors R, Melin B, Palmerud G, Hassmén P, Engström M, Elfsberg Dohns I (1994) Psychophysiological stress and EMG activity of the trapezius muscle. International Journal of Behavioral Medicine 1:354–370
Lundberg U, Forsman M, Zachau G, Eklöf M, Palmerud G, Melin B, Kadefors R (2002) Effects of experimentally induced mental and physical stress on motor unit recruitment in the trapezius muscle. Work & Stress 16:166–178
Macfarlane GJ, Hunt IM, Silman AJ (2000) Role of mechanical and psychosocial factors in the onset of forearm pain: prospective population based study. British Medical Journal 321:676–679
McNulty WH, Gevirtz RN, Hubbard DR, Berkoff GM (1994) Needle electromyographic evaluation of trigger point response to a psychological stressor. Psychophysiology 31:313–316
Melin B, Lundberg U (1997) A biopsychosocial approach to work-stress and musculoskeletal disorders. Journal of Psychophysiology 11:238–247
Meulenbroek RGJ, Van Galen GP, Hulstijn M, Hulstijn W, Bloemsaat G (2005) Muscular co-contraction covaries with task load to control the flow of motion in fine motor tasks. Biological Psychology 68:331–352
Milner TE (2004) Accuracy of internal dynamics models in limb movements depends on stability. Experimental Brain Research 159:172–184
Nafati G, Rossi-Durand C, Schmied A (2004) Proprioceptive control of human wrist extensor motor units during an attention-demanding task. Brain Research 1018:208–220
National Research Council, The Institute of Medicine (2001) Musculoskeletal disorders and the workplace: Low back and upper extremities. National Academy Press, Washington DC
Palmer KT, Cooper C, Walker-Bone K, Syddall H, Coggon D (2001) Use of keyboards and symptoms in the neck and arm: evidence from a national survey. Occupational Medicine-Oxford 51:392–395
Prochazka A (1989) Sensorimotor gain-control - A basic strategy of motor systems. Progress in Neurobiology 33:281–307
Ribot-Ciscar E, Rossi-Durand C, Roll JP (2000) Increased muscle spindle sensitivity to movement during reinforcement manoeuvres in relaxed human subjects. Journal of Physiology-London 523:271–282
Rossi-Durand C (2002) The influence of increased muscle spindle sensitivity on Achilles tendon jerk and H-reflex in relaxed human subjects. Somatosensory and Motor Research 19:286–295
Serrien DJ, Kaluzny P, Wicki U, Wiesendanger M (1999) Grip force adjustments induced by predictable load perturbations during a manipulative task. Experimental Brain Research 124:100–106
Sjogaard G, Kiens B, Jorgensen K, Saltin B (1986) Intramuscular pressure, emg and blood-flow during low-level prolonged static contraction in man. Acta Physiologica Scandinavica 128:475–484
Soechting JF (1984) Effect of target size on spatial and temporal characteristics of a pointing movement in man. Experimental Brain Research 54:121–132
Suzuki M, Shiller DM, Gribble PL, Ostry DJ (2001) Relationship between cocontraction, movement kinematics and phasic muscle activity in single-joint arm movement. Experimental Brain Research 140:171–181
Ter Haar Romeny BM, Van Der Gon JJ, Gielen CCAM (1984) Relation Between Location of A Motor Unit in the Human Biceps Brachii and Its Critical Firing Levels for Different Tasks. Experimental Neurology 85:631–650
Thoroughman KA, Shadmehr R (1999) Electromyographic correlates of learning an internal model of reaching movements. Journal of Neuroscience 19:8573–8588
Van Galen GP, Schomaker LRB (1992) Fitts law as a low-pass filter effect of muscle-stiffness. Human Movement Science 11:11–21
Van Galen GP, Van Huygevoort M (2000) Error, stress and the role of neuromotor noise in space oriented behaviour. Biological Psychology 51:151–171
Van Galen GP, Müller MLTM, Meulenbroek RGJ, Van Gemmert AWA (2002) Forearm EMG response activity during motor performance in individuals prone to increased stress reactivity. American Journal of Industrial Medicine 41:406–419
Van Gemmert AWA, Van Galen GP (1997) Stress, neuromotor noise, and human performance: A theoretical perspective. Journal of Experimental Psychology-Human Perception and Performance 23:1299–1313
Van Loon EM, Masters RSW, Ring C, McIntyre DB (2001) Changes in limb stiffness under conditions of mental stress. Journal of Motor Behavior 33:153–164
Van Roon D, Steenbergen B, Meulenbroek RGJ (2005) Trunk use and co-contraction in cerebral palsy as regulatory mechanisms for accuracy control. Neuropsychologia 43:497–508
Van Schie HT, Wijers AA, Kellenbach ML, Stowe LA (2003) An event-related potential investigation of the relationship between semantic and perceptual levels of representation. Brain and Language 86:300–325
Van Eijsden-Besseling, MD, Peeters, FP, Reijnen, JA, De Bie, RA (2004) Perfectionism and coping strategies as risk factors for the development of non-specific work-related upper limb disorders (WRULD). Occupational Medicine (Oxford) 54:122–127
Visser B, Van Dieën JH (2005) Pathophysiology of work related upper extremity muscle disorders. J Electromyograph Kinesiol (in press)
Waersted M, Westgaard RH (1996) Attention-related muscle activity in different body regions during VDU work with minimal physical activity. Ergonomics 39:661–676
Wahlstrom J, Hagberg M, Johnson PW, Svensson J, Rempel D (2002) Influence of time pressure and verbal provocation on physiological and psychological reactions during work with a computer mouse. European Journal of Applied Physiology 87:257–263
Wann J, Nimmo-Smith I (1991) The control of pen pressure in handwriting - A subtle point. Human Movement Science 10:223–246
Winter DA (1990) Biomechanics and motor control of human movement, 2nd edn. John Wiley, New York
Yamazaki Y, Suzuki M, Ohkuwa T, Itoh H (2003) Coactivation in arm and shoulder muscles during voluntary fixation of a single joint. Brain Research Bulletin 59:439–446
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Bloemsaat, J.G., Meulenbroek, R.G.J. & Van Galen, G.P. Differential effects of mental load on proximal and distal arm muscle activity. Exp Brain Res 167, 622–634 (2005). https://doi.org/10.1007/s00221-005-0066-2
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DOI: https://doi.org/10.1007/s00221-005-0066-2