The Effects Of Varying Load Swimming On Bone Metabolism In Aged Male Mice

To investigate the preventive effects of varying load swimming on male senile osteoporosis, the effect of a 8-week swim training was studied in male mice. Forty Kunming strain of male mice at twelve months old (aged male mice) were randomly assigned to one of five groups: (TM). thirty-minute group; (SM). sixty-minute group; (SW). sixty-minute group loaded with weight; (EC). experimental control; (SC). sedentary control. The TM group swam 30 min a day, the SM group swam 60 min a day, the SW group swam 60 min a day with 2. 5% of body weight attached to their tails. Eight male mice at two months eld (young male mice) was used as young sedentary control (YC). At the end of the training period following blood sampling, all mice were sacrificed and the femur and thoracic vertebral bones were removed for the measurements of bone mineral content index and the content of hydroxyproline(HOP). Later, serums were used for the following measurements: testosterone(T), estradiol(E2), osteocalcin(BGP), alkaline phosphatase(ALP), and calcium(Ca).The results of this study indicated that (l)the bone mineral content index of the femur and thoracic vertebral bones, the content of HOP in thoracic vertebral bones, and the levels of serum T and E2 were significantly lower (P<0.05) in the aged male mice than in the young male mice. However, there were no significant differences in the concentrations of serum Ca, ALP and BGP and the content of HOP in the femur. (2) The bone mineral content index of thoracic vertebral bones was significantly higher (P<0.05) in the SM group than in the EC and the SC groups. The bone mineral content index of femur and thoracic vertebral bones was significantly higher (P<0.05) in the SW group than in the EC and the SC groups. The content of HOP in the femur was significantly higher (P<0. 05) in the SM and the SW groups than in the EC and the SC groups. Moreover, the range of increase of bone mineral content index and the content of HOP was greater in the SW group than in the SM group. (3)Serum T and E2 levels were significantly higher (P<0. 05) in the SM and the SW groups than in the EC and the SC groups. However, there were no significant differences in the concentrations of serum Ca, ALP and BGP.The results of this study showed that suitable load swimming exercises for the aged male mice could suppress age-associated bone loss and the drop of the levels of serum gonadal hormone, and moreover, the preventive effect of swimming exercise on bone loss become much greater with the augmentation of physical work hard. These results suggest that swimming is a suitable fitness activity for elderly men. Suitable load swimming exercises can prevent senile osteoporosis, in addition, it is important and beneficial for elderly men to select much harder physical work load within the scope of his bearing.