Centro de Documentacion de Fundación MAPFRE - Cycle to cycle variability in a repetitive upper extremity task

Notes: Sumario: The purpose of this study was to examine the variability in muscle activity at rest and work during a repetitive task. A total of 20 participants performed a bimanual push task using three frequencies (4, 8, 16 pushes/min), three loads (1 kg, 2 kg, 4 kg) and two grip conditions (no grip, 30% maximum). The coefficient of variation (CoV) of muscle activity was determined for the anterior deltoid, biceps brachii, extensor digitorum and flexor digitorum superficialis. Faster push frequencies and heavier loads had lower workrest ratio CoV and higher mean muscle activity (p < 0.01). Sixteen pushes per minute produced the lowest CoV for the anterior deltoid (p < 0.01), while the 1- kg load produced the lowest CoV for the extensor digitorum and flexor digitorum superficialis (p < 0.01). Changes were driven by the rest phase rather than by the work phase, except for grip decreasing forearm muscle CoV. These findings underscore the importance of variability at rest and indicate that low variability of muscle activity is associated with ergonomic risk factors.Related records: En: Ergonomics : the international journal of research and practice in human factors and ergonomics. - Oxon [United Kingdom] : Taylor & Francis, 2010- = ISSN 0014-0139. - 01/09/2014 Volumen 57 Número 9 - septiembre 2014 Other categories: 875

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