Pain, lower-extremity muscle strength, and physical function among older Mexican Americans

Objective: To examine the relation between pain on weight bearing, lower-extremity muscle strength, and physical function among older Mexican Americans. Design: Cross-sectional study. Setting: Five Southwestern states: Texas, New Mexico, Colorado, Arizona, and California. Participants: A population-based sample of 544 noninstitutionalized Mexican-American men and women age 71 years and older. Interventions: Not applicable. Main Outcome Measures: Pain on weight bearing, lower-extremity muscle strength, and physical function. Results: Of the 544 subjects, 244 (44.9%) reported pain on weight bearing. Mean muscle strength in men ranged from 9.3kg for knee extension, 12.8kg for hip flexion, to 13.0kg for hip abduction. In women, mean strength ranged from 6.6kg for knee extension, 9.5kg for hip flexion, to 8.6kg for hip abduction. Mean of physical function score was 70.7 for men and 60.6 for women. Pain on weight bearing was negatively associated with summary lower-extremity muscle strength only in women (-.05, P<.001) after controlling for all covariates. Pain on weight bearing was negatively associated with physical function in both men (-15.33, P<.001) and women (-11.03, P<.001), and lower-extremity muscle strength was positively associated with physical function in both men (37.77, P<.001) and women (73.50, P<.001), after controlling for all covariates. Conclusions: Among older Mexican Americans, the presence of pain was associated with decreased muscle strength in women and decreased physical function in both men and women. High muscle strength was associated with high physical function in both men and women.