Summaries of Our Applied Research: Upper Extremity Work
Shoulder Muscle Fatigue During Repetitive Tasks as Measured by Electromyography and NearInfrared Spectroscopy
Summary: This study quantified shoulder muscle fatigue during repetitive exertions similar to motions found in automobile assembly tasks. There was found to be significant shoulder muscle fatigue as a function of shoulder angle, task frequency, and force level. Ergonomists should examine interactions of force and repetition as well as shoulder angle and repetition when evaluating the risk of shoulder MSDs. For activities requiring work at ten repetitions per minute, the impact of force level was found to be much greater than at reduced levels of repetition.
Summary: Although the benefits of gloves to hand safety are well known, less information exists regarding the effects gloves may have on the quality and efficiency of work performed, or the potential risk due to cumulative trauma. This study investigated the effects of different types and sizes of gloves on external grip force and muscle activity. It was found that:
Generally, gloves reduced peak grip strength.
Different glove types have different effects on peak grip strength. Thinner, more elastic materials such as jersey and surgical gloves allowed for the greatest external force output.
Barehanded exertions, and exertions performed wearing surgical and oversized surgical gloves, provided greater transfer of flexor muscle activity to grip force than many of the other glove types.
Better-fitting gloves resulted in better transmission of muscular force to measured grip force.
Significant differences exist between the ratios of force to coactivity between different glove types.