The Effect of Detraining on Bone

Physical activity has been recommended for the treatment and even prevention of osteoporosis. This is because physical activity can potentially increase bone mass and strength in the early years of life and reduce the risk of falling in older populations. However, a key question that remains to be answered is whether a high bone mineral density (BMD) resulting from physical activity is sustained despite decreased activity. The aim of this review is to describe the effects of decreased levels of physical activity on bone. A comprehensive search of Medline, EMBASE, and the Cochrane controlled trials register was conducted. Previous studies have reported that benefits from prior physical activity seem to be eroded after cessation of this activity, at least for bone sites that are rich in trabecular bone such as the clinically important proximal femur. In bone sites rich in cortical bone, there appeared to be long-term beneficial effects of physical activity. In conclusion, bone gain through physical activity is lost in bone sites rich in trabecular bone if the activity is not maintained. However, current knowledge is limited and further prospective research into the effect of detraining is recommended.