Tohoku J. Exp. Med., 1998, 185 (1)

Effects of Exercise at Different Ages on Bone Density and Mechanical Properties of Femoral Bone of Aged Mice

AKIO HOSHI,1,2 HIROMI WATANABE,2 MOMOKO CHIBA2 and YUTAKA INABA2

1Department of Health and Physical Education, Nippon Dental University, Tokyo 102-8159, and 2Department of Epidemiology and Environmental Health, Juntendo University School of Medicine, Tokyo 113-8421

  • We determined the bone density and mechanical properties of bone specimens from 5 groups of aged mice which had been subjected to voluntary exercise at different ages. ICR 10-week-old female mice were divided into control (C), and exercise-trained during age periods of 10-70 weeks (EE), 10-30 weeks (GPE), 30-50 weeks (MPE) and 50-70 weeks (APE). It was found that in the exercise-trained groups body weight gain was suppressed during the exercise-training period, and that de-training accelerated weight gain. Bone density was significantly higher in all the exercise-trained groups than in the C group and cortical thickness index (CTI) was higher in the exercise-trained groups, except for the APE group. Maximum breaking force, ultimate stress and elasticity in the exercise-trained groups were higher than in the C group except for the APE group, whereas deformation in the APE group had a tendency to be higher than in the other groups. Blood C-terminal parathyroid hormone, calcitonin and calcium concentrations were similar among every group, but phosphorus concentrations tended to be higher in the exercise-trained groups than in the C group. These observations suggest that exercise-training at every age suppresses age-associated bone loss, and that the effect of exercise during youth is greater than that during old age. The results of this study suggest that the effect of exercise on bone at an older age is different from that at other ages.
    Key words--- bone density; mechanical properties of the bone; Ca metabolism; voluntary exercise
    © 1998 Tohoku University Medical Press

    Tohoku J. Exp. Med., 1998, 185, 15-24
    Address for reprints: Akio Hoshi, Department of Health and Physical Education, Nippon Dental University, Tokyo 102-8159, Japan.

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