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 morphometrical 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-week-old (adult) rats were divided into following four groups: Young-Sedentary (YS), Young-Exercised (YE), Adult-Sedentary (AS), and Adult-Exercised (AE). The exercised groups performed jump-training (height = 40 cm, 10 jumps/day, 5 days/week) for 8 weeks followed by 24 weeks of 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-weeks of detraining, the beneficial effects of training on bone mass and strength were preserved associated with morphometrical changes, such as periosteal perimeter, cortical area, and moment of inertia. There were no significant age-exercise interactions in such parameters except for periosteal perimeter. These results suggest that there are few differences in bone accommodation and maintenance by training and detraining between young and adult rats.