The volume of brisk walking is the key determinant of BMD improvement in premenopausal women.

SUMMARY

Osteoporosis is an increasing health problem in postmenopausal women. Our findings indicated that long-term brisk walking with a volume greater than 16 per week is effective for improving BMD in premenopausal women.

PURPOSE

To examine the effects of brisk walking on bone mineral density (BMD) in premenopausal women, and further determine the effective frequency, intensity, time and volume (frequency x duration) of brisk walking for training strategy prescription.

METHODS

222 healthy premenopausal women were recruited for BMD measurement. According to the survey of their physical activity level, 84 subjects (age: 46±1.8) whose physical activity index ≥40 were categorized into the brisk walking group, and 138 subjects (age: 47±2.2) whose physical activity index <40 were assigned to the sedentary group. The BMD of these two groups were statistically compared with an independent t test. Next, 35 subjects from the original sedentary group were recruited for BMD measurement after 2-year moderate brisk walking. According to the volume of physical activity per week, they were divided into the control group (n = 10, aged 49±0.9), volume 8 group (n = 4, aged 48±1.2), volume 12 group (n = 7, aged 49±1.4), volume 16 group (n = 8, aged 49±1.3), and volume 20 group (n = 6, aged 49±1.5). ANOVA was used to analyze BMD before and after brisk walking among the five groups.

RESULTS

The BMD in the brisk walking group (1.00±0.008 g/cm2) was significantly higher than that in the sedentary group (0.89±0.008 g/cm2) (P<0.001). Stepwise regression analysis revealed that the volume of brisk walking was significantly correlated with BMD (P<0.001). In particular, brisk walking with a volume greater than 16 (a score of duration up to 4 and a score of frequency up to 4 or 5) per week is effective for improving BMD in premenopausal women (P = 0.03, P = 0.002, respectively).

CONCLUSIONS

Long-term brisk walking is an efficient way to improve BMD. Taking brisk walks for 30 minutes per day 3 or more times per week (volume>16) is recommended to prevent bone loss in premenopausal women.