Comparison of Lower Limb Muscle Strength Imbalances and Gait Performance in Postmenopausal Women with Healthy and Low Bone Mineral Density.

INTRODUCTION

Osteoporosis and osteopenia increase the risk of fractures, impair physical function, and may lead to loss of independence in postmenopausal women. This study examined differences in muscle strength imbalances and gait performance in postmenopausal women with healthy and low bone mineral density (BMD).

METHODS

In this cross-sectional study, a total of 85 participants underwent body composition and BMD measurements using dual-energy X-ray absorptiometry (DXA, Hologic QDR Horizon A). Muscle strength was evaluated using a handgrip strength test, and knee flexor and extensor strength were analyzed using an isokinetic dynamometer (Humac Norm CSMI). Gait performance was evaluated by a 10 m walking test, a 3 m backward walking test, and a 6-minute walking test. According to whole-body BMD T-score, participants were divided into a Healthy BMD group (n = 30) and a Low BMD group (n = 55).Normality was assessed using the Shapiro-Wilk test. Between-group differences and side-to-side differences in strength parameters were analyzed using the Mann-Whitney U-test, and associations between gait parameters, muscle strength, and BMD were examined using Spearman's rank correlation coefficient. Additionally, multivariable analyses, including multivariate analysis of covariance (MANCOVA) and binary logistic regression, were performed to adjust for age and lean body mass. Statistical significance was set at p < 0.05.

RESULTS

Low BMD status was associated with reduced muscle strength, particularly lower knee extensor strength. After adjustment for age and lean body mass, right knee extensor strength remained independently associated with low BMD status in binary logistic regression (OR = 0.957, 95% CI: 0.927-0.988, p = 0.007). No significant association was observed between gait performance and BMD.

DISCUSSION: These results suggest that lower limb muscle strength, particularly knee extensor strength, may be a relevant functional factor to consider in postmenopausal women with low BMD, as reduced strength may be associated with increased fracture risk in older women.