Importance: Muscular strength is an important resilience marker relevant to maintaining functional independence and longevity.
Objective: To examine associations between muscular strength and mortality in women aged 63 to 99 years accounting for accelerometer-measured physical activity and sedentary behavior, systemic inflammation, and other markers of aging.
Design, setting, and participants: The Objective Physical Activity and Cardiovascular Health study was a prospective cohort study from baseline (March 2012 to April 2014) through February 19, 2023. Participants were ambulatory women aged 63 to 99 years who completed physical performance testing and 7 days of accelerometer wear.
Exposures: Dominant hand grip strength,measured in kg by quartile (1: <14, 2: 14-19, 3: 19-24, and 4: >24) and time in seconds to complete 5 unassisted chair stands by quartile (standard criteria: 1: >16.7, 2: 16.6-13.7, 3: 13.6-11.2, and 4: ≤11.1).
Main outcome and measure: All-cause mortality.
Results: The present study included 5472 women (mean [SD] age, 78.7 [6.7] years; 1851 [33.8%] Black; 915 [16.7%] Hispanic/Latina; 2706 [49.5%] White) followed up for a mean (SD) of 8.4 (2.4) years. There were 1964 deaths during the study period. Controlling for age and sociodemographic, lifestyle, and clinical factors, significant inverse trends in mortality were evident across quartiles 2 through 4 of grip strength (quartile 2: hazard ratio [HR], 0.94; 95% CI, 0.85-1.06; quartile 3: HR, 0.85; 95% CI, 0.75-0.97; quartile 4: HR, 0.67; 95% CI, 0.58-0.78; P for trend < .001) and chair stand time (quartile 2: HR, 0.79; 95% CI, 0.69-0.88; quartile 3: HR, 0.76; 95% CI, 0.67-0.87; quartile 4: HR, 0.63; 95% CI, 0.54-0.73; P for trend < .001). Further controlling simultaneously for sedentary time and moderate to vigorous physical activity attenuated associations (grip strength: quartile 2: HR, 0.95; 95% CI, 0.86-1.07; quartile 3: HR, 0.87; 95% CI, 0.76-0.99; quartile 4: HR, 0.70; 95% CI, 0.61-0.82; P for trend < .001; chair stands: quartile 2: HR, 0.82; 95% CI, 0.73-0.92; quartile 3: HR, 0.82; 95% CI, 0.71-0.93; quartile 4: HR, 0.69; 95% CI, 0.59-0.79; P for trend < .001). Similar inverse associations were observed when controlling for walking speed and the inflammatory marker C-reactive protein. Magnitudes of association did not differ across subgroups defined by age, race and ethnicity, body mass index, moderate-to-vigorous physical activity, sedentary time, or timed walk.
Conclusions and relevance: In this study of ambulatory older women, greater muscular strength was associated with lower mortality even when controlling for accelerometer-measured PA and sedentary time, walking speed, and systemic inflammation. These findings suggest that assessing strength and promoting its maintenance are instrumental for optimal aging.