The effects of obesity on muscle activity during lifting tasks

By Colim, A.S.; Arezes, P.M.; Flores, P.; Braga, A.C.

Occupational Safety and Hygiene III



Obesity is an emerging public health problem affecting the industrialized countries. Besides, obesity seems to negatively affect the individuals’ work performance. In occupational contexts, manual lifting tasks are common and can produce significant muscle loading. With the aim of analysing the possible effect of obesity on workers’ muscle activity, surface electromyography (EMG) data were collected from six muscles recruited during these tasks. In the present study, different tasks of manual lifting were performed by 14 participants with different obesity levels. EMG data normalization was based on the percentage of maximum contraction during each task (MCT). The muscles’ activation times (AT) before each task were also calculated. The current study suggests that obesity can increase the MCT and the delays on muscles’ AT. This investigation proposes obesity as an individual risk factor for the development of work-related musculoskeletal disorders (WMSD), throughout lifting, and reinforces the need to study it more deeply.


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