BACKGROUND: The lumbar extensor muscles (LEMs) play an important role in body posture and physical function in older adults. Because lumbar extensor strength decreases more rapidly than limb muscle strength with age, it should be evaluated to aid healthy aging. This study investigated the association between LEM strength and physical performance in community-dwelling older adults. METHODS: This prospective observational cohort study of spinal sarcopenia (SarcoSpine) was conducted at a single center. One hundred and ten consecutive individuals who completed the baseline survey, including conventional sarcopenic indices, lumbar spine three-dimensional magnetic resonance imaging, isokinetic lumbar extensor strength, and physical performance tests (Short Physical Performance Battery, Berg Balance Scale, and Back Performance Scale [BPS]), were enrolled. A multivariate linear regression analysis was performed to determine the variables for evaluating their association with LEM strength. RESULTS: Among the conventional sarcopenic indices, gait speed was significantly correlated with Short Physical Performance Battery results and Berg Balance Scale score in men and women. Handgrip strength was significantly correlated with the BPS score for both sexes. In the multivariable linear regression, age (β = -2.12, p <
.01) and BPS score (β = -3.54, p = .01, R2 = .29) were independent indicators of LEM strength. CONCLUSIONS: Our findings reveal the substantial association between LEM strength and BPS score in older women. The targeted intervention aimed at improving the LEMs strength would be needed to enhance physical performance in the aging population.