Effects of postmenopausal exercises on the bone mineral density

Introduction

In postmenopausal females, secretion of estrogen is reduced, resulting in decreases in the bone mineral density. To prevent decreases in the bone mineral density, exercise with mechanical stress is important. However, effects of swimming on the bone metabolism remain unclarified. In this study, we examined the effects of swimming on the bone mineral density and bone-metabolic dynamics in postmenopausal females.

Methods

The subjects were 20 females, consisting of 10 who were taking a swimming course in a sports club (mean age, 64.30±5.26 years; mean exercise period, 4.20±1.03 years) as the exercise group and 10 who were taking a cultural course (handcrafts) (mean age, 63.20±5.92 years) as the non-exercise group.
The bone mineral density was measured by the dual energy X-ray absorption method (DXA: QDR-2000, Hologic Inc.). The bone mineral density of the whole body, radius, lumbar vertebrae, and proximal regions of the femur were measured. The blood concentration of calcium and urinary concentration of deoxypyridinoline were measured as biochemical markers of bone turnover.

Results

The bone mineral density in the whole body and local regions was slightly higher in the exercise group than in the non-exercise group. The bone mineral density per body weight in Ward’s region of the proximal femur and the proximal femur region was slightly higher in the exercise group than in the non-exercise group.
In the exercise group, the urinary concentration of deoxypyridinoline was significantly lower after swimming than before swimming (p<0.01).

Discussion/Conclusions

Swimming the exercise utilizing water resistance induced bone strain , and it was effective in increasing the bone mineral density in the proximal femur. The findings indicated that swimming enhanced ossification, maintained the postmenopausal bone mineral density, and affected bone-metabolic dynamics.