Effects of the maximum acceptable level of physical activity on physiological and psychological strains for Taiwanese females of different age groups

The prevalence of musculoskeletal disorders (MSDs) across different countries, with resulting DAFW and WC claims, indicates that MSDs are significant health problems in the work environment. As the global labor force ages, maintaining regular and adequate levels of physical activity (PA) has been recommended by the World Health Organization (WHO) as one of the protective and proactive strategies to reduce the risk of musculoskeletal disorders, especially for mid-life and older adults. Currently, inconsistent findings have been reported regarding the effectiveness of PA interventions on reducing musculoskeletal symptoms. The inconsistent effects may come from different levels of PA intervention administered across studies or the scarcity of studies that fully complied with the WHO’s recommended PA guideline. Accordingly, this study adopts a psychophysical approach for Taiwanese females of three age groups to determine the maximum acceptable level of physical activity (MAL-PA) using laboratory-owned shoulder-upper extremity and low back-pelvis fitness training equipment. In addition, the strain levels associated with the MAL-PA determined were assessed objectively and subjectively to be further examined for their differences with existing or future studies. The results show that the determined MAL-PA decreased with age while performing functional strengthening exercise using shoulder-upper extremity fitness training equipment and increased with age while performing functional strengthening exercise using low back-pelvis fitness training equipment. The mean heart rates measured associated with MAL-PA showed that the participants are pacing themselves appropriately during each MAL-PA simulation. Subsequently, MAL-PA intervention could be adopted in future studies to make a comparative evaluation of the effects on reducing musculoskeletal symptoms to preserve the worker’s health and safety when achieving and maintaining an active, productive, and prolonged working life.