Effects of bone-specific physical activity on body composition, bone mineral density, and health-related physical fitness in middle-aged women.

Purpose: The study aimed to determine the effects of bone-specific physical activity on body composition, bone mineral density (BMD), and health-related physical fitness in middle-aged women.

Methods: One hundred eighty-six middle-aged women aged 31-49 years participated in this study. The subjects were divided into tertile groups according to the level of physical activity (low-score group, n=62; middle-score group, n=62; high-score group, n=62). Bone-specific physical activity participation was assessed using the bone-specific physical activity questionnaire. Body composition and BMD were measured using dual-energy X-ray absorptiometry. Health-related physical fitness test included isometric muscle strength (grip strength), muscular endurance (sit-ups), flexibility (sit and reach), and cardiorespiratory fitness (maximal oxygen uptake [VO2max]).

Results: The high-score group had a significantly higher fat-free mass (p=.045, partial eta-squared value [ηp2]=.033) than the middle- and low-score groups, whereas the high-score group had significantly lower percent body fat (p=.005, ηp2=.056) than the other two groups. Whole-body BMD (p=.034, ηp2=.036) and lumbar BMD (p=.003, ηp2=.060) were significantly higher in the high-score group than in the low-score group. The high-score group performed significantly better for grip strength (p=.0001, ηp2=.101), sit-ups (p=.0001, ηp2=.108), and VO2max (p=.0001, ηp2=.092) than the other two groups.

Conclusion: The present study suggests that bone-specific physical activity could be useful in improving body composition, BMD, and health-related physical fitness in middle-aged women, significantly enhancing their BMD and health conditions.