Effects of alfacalcidol on back extensor strength gained through back extensor exercise in postmenopausal women with osteoporosis.

Objective: The aim of this study was to investigate the additive effect of the active form of vitamin D3 on the gain in back extensor strength through a back extensor exercise.

Design: A total of 107 postmenopausal women with osteoporosis were randomly divided into two groups: the D3 group and the control group. Both groups were treated with calcium and alendronate and undertook the back extensor exercise. Alfacalcidol was prescribed only to the D3 group.

Results: There was no significant difference in the demographic data between the two groups. Ninety-four participants who completed a 4-mo intervention were subjected to per-protocol analysis. There was no significant difference in the improvement in back extensor strength between two the groups (P = 0.349). All subjects were further categorized into two subgroups by age. In the older subgroup (≥68 yrs), no significant difference was found in the improvement in back extensor strength (P = 0.316). In the younger subgroup (<68 yrs), the back extensor strength in the D3 group was significantly more improved than in the control group (P = 0.034).

Conclusions: The results of this study suggest that the administration of the active form of vitamin D3 enhances the beneficial effects of the back extensor exercise in patients younger than those in their late 60s.