Skeletal Muscle Health, Physical Performance, and Lower Urinary Tract Symptoms in Older Adults: The Study of Muscle, Mobility, and Aging.

Abstract

Background: Lower urinary tract symptoms (LUTS) and mobility limitations are bidirectionally associated among older adults, but the role of skeletal muscle remains unknown. We evaluated cross-sectional associations of muscle health and physical performance with LUTS.

Methods: We used data from 377 women and 264 men aged >70 years in the Study of Muscle, Mobility and Aging (SOMMA). LUTS and urinary bother were assessed using the LURN Symptom Index-10 (SI-10; higher = worse symptoms). Muscle mass and volume were assessed using D3-creatine dilution (D3Cr) and magnetic resonance imaging. Grip strength and peak leg power assessed upper/lower extremity physical performance. 400-m walk, Short Physical Performance Battery (SPPB), and Four Square Step Test (FSST) assessed global physical performance. Mobility Assessment Tool-short form (MAT-sf) assessed self-reported mobility. We calculated Spearman correlation coefficients adjusted for age, body mass index, multimorbidity, and polypharmacy, chi-square tests, and Fisher's Z-test to compare correlations.

Results: Among women, LURN SI-10 total scores were inversely correlated with FSST (rs = 0.11, p = .045), grip strength (rs = -0.15, p = .006), and MAT-sf (rs = -0.18, p = .001), but not other muscle and physical performance measures in multivariable models. LURN SI-10 was not associated with any of these measures among men. Forty-four percent of women in the lowest tertile of 400-m walk speed versus 24% in the highest tertile reported they were at least "somewhat bothered" by urinary symptoms (p < .001), whereas differences among men were not significant.

Conclusions: Balance and grip strength were associated with LUTS severity in older women but not men. Associations with other muscle and physical performance measures varied by LUTS subtype but remained strongest among women.