Is strength training associated with mortality benefits? A 15year cohort study of US older adults.

Background: The relationship between strength training (ST) behavior and mortality remains understudied in large, national samples, although smaller studies have observed that greater amounts of muscle strength are associated with lower risks of death. We aimed to understand the association between meeting ST guidelines and future mortality in an older US adult population.

Methods: Data were analyzed from the 1997-2001 National Health Interview Survey (NHIS) linked to death certificate data in the National Death Index. The main independent variable was guideline-concordant ST (i.e. twice each week) and dependent variable was all-cause mortality. Covariates identified in the literature and included in our analysis were demographics, past medical history, and other health behaviors (including other physical activity). Given our aim to understand outcomes in older adults, analyses were limited to adults age 65years and older. Multivariate analysis was conducted using multiple logistic regression analysis.

Results: During the study period, 9.6% of NHIS adults age 65 and older (N=30,162) reported doing guideline-concordant ST and 31.6% died. Older adults who reported guideline-concordant ST had 46% lower odds of all-cause mortality than those who did not (adjusted odds ratio: 0.64; 95% CI: 0.57, 0.70; p<0.001). The association between ST and death remained after adjustment for past medical history and health behaviors.

Conclusions: Although a minority of older US adults met ST recommendations, guideline-concordant ST is significantly associated with decreased overall mortality. All-cause mortality may be significantly reduced through the identification of and engagement in guideline-concordant ST interventions by older adults.