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Bones benefits gained by jump training are preserved after detraining in young and adult rats

¹Laboratory for Exercise Physiology and Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota; ²Department of Sports, Faculty of Sports, Kyushu Kyoritsu University, Kitakyushu; ³School of Education, Tokyo University and Graduate School of Social Welfare, Nagoya; and ⁴Faculty of Health Science, Suzuka University of Medical Science, Suzuka, Japan

Submitted 22 August 2007 ; accepted in final form 26 June 2008

We investigated the osteogenic responses to jump training and subsequent detraining in young and adult male rats to test the following hypotheses: 1) jump training has skeletal benefits; 2) these skeletal benefits are preserved with subsequent detraining throughout bone morphometric changes; and 3) there are no differences between young and adult rats during detraining in terms of the maintenance of exercise-induced changes. Twelve-week-old (young) and 44-wk-old (adult) rats were divided into the following four groups: young-sedentary, young-exercised, adult-sedentary, and adult-exercised. The exercised groups performed jump training (height = 40 cm, 10 jumps/day, 5 days/wk) for 8 wk followed by 24 wk of being sedentary. Tibial bone mineral content and bone mineral density in vivo significantly increased with jump training, and the effects were maintained after detraining in both the young and adult exercised groups, although the benefits of training became somewhat diminished. After 24 wk of detraining, the beneficial effects of training on bone mass and strength were preserved and associated with morphometric changes, such as periosteal perimeter, cortical area, and moment of inertia. There were no significant age-exercise interactions in such parameters, except for the periosteal perimeter. These results suggest that there are few differences in bone accommodation and maintenance by training and detraining between young and adult rats.

high-impact training; training cessation; bone morphometry; age

This article has been cited by other articles:

				T Kato, T Yamashita, S Mizutani, A Honda, M Matumoto, and Y Umemura Adolescent exercise associated with long-term superior measures of bone geometry: a cross-sectional DXA and MRI study Br. J. Sports Med., November 1, 2009; 43(12): 932 - 935. [Abstract] [Full Text] [PDF]