Greater skeletal muscle strength was associated with lower all-cause mortality among ambulatory older women, even after accounting for several mortality risk factors and in those not meeting aerobic activity guidelines, according to results from the OPACH study published in JAMA Network Open by Michael J. LaMonte, PhD, of the State University of New York at Buffalo, and colleagues.

“These findings suggest that strength can be easily assessed in the clinical setting, and promoting its maintenance could play a key role in optimal aging,” the researchers wrote.

Study Details

In this prospective cohort study, the researchers analyzed 5,472 ambulatory women aged 63 to 99 years (mean age, 79 years; 34% Black, 17% Hispanic/Latina, 50% White) who completed in-home examinations between 2012 and 2014, including physical performance testing and 7 days of hip-worn accelerometer monitoring.

Participants were followed for a mean of approximately 8 years; 1,964 deaths (36%) occurred during follow-up.

Muscular strength was assessed using dominant-hand grip strength measured by dynamometer and time to complete five unassisted chair stands. Strength measures were categorized into quartiles (1–4) as follows:

• Grip strength: <14, 14–19, 20–24, and >24 kg

• Chair stand time: ≥16.7, 16.6–13.7, 13.6–11.2, and ≤11.1 seconds

Key Findings

After adjustment for age, sociodemographic characteristics, lifestyle factors, and clinical variables, statistically significant inverse trends in mortality were observed across quartiles 2 through 4 vs 1 for both grip strength and chair stand performance.

Women in the highest grip strength quartile had an approximately 33% lower likelihood of death compared with those in the lowest quartile. Those in the fastest chair stand quartile had an approximately 37% lower likelihood of death compared with those in the slowest quartile.

Further adjustment for sedentary time and moderate-to-vigorous physical activity attenuated but did not eliminate the associations. In these models, the highest vs lowest quartile corresponded to an approximately 30% lower risk of death for grip strength and 31% lower risk for chair stand performance.

Similar inverse associations were observed after additional adjustment for walking speed and C-reactive protein.

The researchers reported that magnitudes of association did not significantly differ across subgroups defined by age, race and ethnicity, body mass index, moderate-to-vigorous physical activity, sedentary time, or timed walk. However, within several subgroup analyses, grip strength consistently remained significantly associated with mortality, whereas chair stand performance was not statistically significant in all subgroups. When stratified by meeting aerobic activity guidelines, grip strength remained associated with lower mortality risk, while chair stand time was not significantly associated with mortality in either group.

The researchers concluded:

“In this cohort study of 5,472 women aged 63 to 99 years, two common strength tests were associated with significantly lower mortality risk after controlling for sociodemographic and clinical characteristics, accelerometer-measured physical activity and sedentary behavior, and timed walk. Muscle strength was associated with lower mortality even in women not meeting guideline-recommended activity levels.”

“Our finding supports current national recommendations that promote participation in muscle strengthening activity for optimal aging and longevity,” they added. “To improve guideline recommendations, future research should better characterize the type and amounts of muscular strengthening activity associated with more specific outcomes across the health span.”

Dr. LaMonte reported no conflicts of interest. Drs. Seguin-Fowler, Eaton, Di, and LaCroix reported relationships as detailed in the original publication. For full disclosures, see the study at JAMA Network Open.

Source: JAMA Network Open