The effects of a 5-month physical training on iliac bone morphology in monkeys.

The present study was designed to provide data on the effects on bone of 5 months of daily exercise in nonhuman primates. The subjects were five male rhesus monkeys with mature skeletons with a body mass of 8-10 kg. The exercise schedule selected to provide endurance training was a daily continuous 1-h climbing task. An iliac crest bone biopsy was performed prior to and at the end of the physical training. The histomorphometric bone study was based upon bone mass and bone cell activity measurements made on nondecalcified bone slides, using trichromic and fluorescent labelling techniques. Results showed a decrease in bone formation, resulting in reduced bone mass at the end of the 5 months. This effect is suggested to be related to the unphysiological climbing regimen imposed on these animals which are naturally used to short periods of rapid exercise. From these investigations it was concluded that even if it is well tolerated, long-term physical endurance training can induce bone loss in primates. Further investigations are needed to determine with accuracy the relationships between bone physiology and physical exercise, and particularly with regard to its type, intensity and duration.