Few data exist on the association between muscle-strengthening activity (MSA) and mortality rates.
PURPOSE: To examine prospectively the association between muscle-strengthening activity and mortality from all causes, cardiovascular disease (CVD), and cancer in older women, and to evaluate the shape of any dose-response.
METHODS: In 2001, 28,882 women (average (SD) age, 62.2 (6.8) years) from the Women’s Health Study who were free of CVD, diabetes, and cancer reported their physical activities, including MSA. They were followed through 2014 for mortality. Cox proportional hazards models estimated hazard ratios for mortality and restricted cubic splines were used to investigate dose-response.
RESULTS: During an average follow-up of 11.6 years, 2591 deaths occurred (360 from CVD and 706 from cancer). After adjusting for covariables including time in moderate to vigorous aerobic activities, the cumulative average time per week in MSA showed a quadratic association with all-cause mortality (P, linear trend=0.14; P, quadratic trend<0.001); hazard ratios across 5 categories of time in MSA (0; 1 to 19; 20 to 59; 60 to 149; 150+ minutes/week) for all-cause mortality were 1.0 (referent), 0.76 (95% confidence interval 0.68 to 0.86), 0.72 (0.62 to 0.84), 0.77 (0.63 to 0.95), and 1.04 (0.70 to 1.52). A significant quadratic association was also observed for CVD death (P, linear trend=0.42; P, quadratic trend=0.01) but not cancer death (P, linear trend=0.98; P, quadratic trend=0.37). Spline models also indicated a J-shaped non-linear association for all-cause mortality (P=0.02); hazard ratios of <1.00 were observed between 1 to 142 min/week of MSA, compared with none, while hazard ratios of >1.00 were seen with >142 min/week of MSA.
CONCLUSIONS: Time in MSA showed a J-shaped association with all-cause mortality in older women.
Funded by NIH grants CA047988, CA182913, HL043851, HL080467, and HL099355.