Effects of a calcium-deficient diet and resistance exercise on bone in male and female rats of different biological maturity

Abstract

Abstract We investigated the effects of resistance exercise, sex, and biological maturity on bone in rats fed a calcium (Ca)-deficient diet. Growing (age: 4–7 weeks) and mature (age: 12–15 weeks) rats were divided into four groups: sedentary and climbing exercise groups on a Ca-sufficient diet (5 g Ca/kg), and sedentary and climbing exercise groups on a Ca-deficient diet (1 g Ca/kg). Exercise increased the muscle weight in both sexes of the growing rats, but not in both male and female mature rats. In rats fed a Ca-deficient diet, the weight, central axis width, breaking energy, and stiffness of the femur were significantly lower in both sexes of growing rats and were not affected by exercise. In mature rats, neither a Ca-deficient diet nor exercise had any effect on these measurements in either sex. The rupture energy and stiffness of the femur were decreased by the Ca-deficient diet in growing rats of both sexes, but exercise did not suppress this weakening. In mature rats of both sexes, the Ca-deficient diet did not induce fragility of the femur.