Rest period and object load effects on upper limb muscle strength recovery for manual load transfer

This study examined the rest period and object load influence on upper limb muscle strength recovery after a simulated 9 min intermittent repetitive manual work. Eight task conditions consisting of four rest periods (2.25, 4.5, 9, 13.5 min) and two object loads (1 and 2 Kg) were studied. Twelve male subjects were recruited to participate. Four muscles in the right upper limb were tested using surface electromyography. Heart rate and rating of fatigue were measured during the experiment. The experimental results showed that the rest period of 4.5 min, which was not the largest, could be the most efficient recovery level that might result in obtaining better muscle strength recovery and larger heart rate reduction with a shorter rest time. The study results provided fundamental work/rest pattern data that could be considered in early intervention strategies for muscle fatigue prevention at worksites. Limitations and recommendations regarding the current study were highlighted. Relevance to industry: Upper limb repetitive manual load transfer tasks are common at worksites, and can result in work-related musculoskeletal disorders. The results from this study should be useful in work/rest scheduling for repetitive manual load transfer tasks.

Automated summary

This study examined the effects of rest period and object load on upper limb muscle strength recovery. The findings suggest that a rest period of 4.5 minutes may be the most efficient for muscle strength recovery. This research provides important data for early intervention strategies to prevent muscle fatigue.