Exploring subjective and objective localized muscle fatigue responses at recommended upper limb ergonomics limits

Abstract

Localized muscle fatigue (LMF) has been associated with numerous negative outcomes, including a reduction in task performance and development of musculoskeletal injury. Thus, the quantification of LMF development in response to occupational task demands has become a major focus in the ergonomics literature. In this thesis, Study 1 showed how a familiarization session, including targeted feedback on ratings of perceived fatigue (RPF), resulted in a significant improvement in error between RPF and measures of force output and electromyography. Study 2 compared the LMF response at three different “acceptable” limits along the ACGIH® threshold limit curve, which describes acceptable relative force intensity for a given level of repetitive work (i.e. duty cycle). Exposures at higher duty cycles (and lower force intensity) were found to elicit the largest LMF responses. This thesis concludes with practical recommendations to help ergonomists better assess and prevent the accumulation of excessive LMF in the workplace.