Validating the recommended cumulative rest allowance equation for use in workload management

The Recommended Cumulative Rest Allowance (RCRA) equation estimates rest requirements based on effort intensity and duty cycle and may be important when optimizing daily workload to maintain productivity without undue muscle fatigue development; however, its validity has not been confirmed. Thus, the purpose of this study was to investigate whether muscle fatigue accumulates when rest time is insufficient according to the RCRA equation, and whether no fatigue occurs in protocols deemed to have sufficient or excess rest. Thirty-two participants performed isometric triceps extensions under three protocols: insufficient rest, sufficient rest, and excess rest for the same total work. Muscle fatigue was assessed by comparing maximum voluntary exertions (MVE) before and after each protocol and investigating amplitude and frequency changes in surface electromyography recorded from the triceps. MVE significantly decreased by an average of 2.4 % after all protocols.

Participants showed significantly higher EMG amplitudes and lower mean power frequencies over time during the insufficient rest protocol, however, no changes were observed in the sufficient and excess rest protocols. This provides evidence supporting that the RCRA may be a useful tool to optimize workloads in the workplace; however, studies using longer exposure times are necessary to confirm its effectiveness.