Dose-dependent association between muscle-strengthening activities and all-cause mortality: Prospective cohort study among a national sample of adults in the USA

BACKGROUND: We have a limited understanding of the association between behavioural participation in muscle-strengthening activities (MSA) and all-cause mortality.

AIM: To determine the effect of MSA on all-cause mortality, and examine a potential dose-response relationship between the frequency with which MSA are performed and the incidence of all-cause mortality.

METHODS: Individuals (8772 adults aged≥20years) from the 2003-2006 National Health and Nutritional Examination Survey were evaluated for baseline characteristics, then followed for an average of 6.7years. MSA were assessed at baseline as the number of self-reported sessions completed within the past 30days. Analyses were performed in 2015.

RESULTS: Only 18.6% of individuals met MSA guidelines (2-3 MSA sessions/week) at baseline, while those performing any form of MSA had a 23% reduced risk of all-cause mortality (hazard ratio [HR]: 0.77; 95% confidence interval: 0.60-0.98; P=0.04). Additionally, we created a five-category variable to determine whether a dose-response relationship existed between MSA and premature mortality; only individuals performing 8-14 sessions over a 30-day period (current MSA guidelines) had a reduced risk of all-cause mortality (HR: 0.70; P=0.02). Results were similar for CVD-specific mortality.

CONCLUSION: The national recommendations that 2-3 MSA sessions be performed per week appear to be most effective at reducing the risk of premature all-cause mortality; however, despite these recommendations, the majority of the adult population in the USA still fails to perform any MSA. Future studies should determine strategies for increasing adherence to these established guidelines.