[Physical activities and bone mass in women]

The mechanism and its effects on the bone mass are discussed. The bone disorders of spacemen show the necessity of physical constraints. The intensive physical exercise can increase disturbances in the bone remodeling. But the hormonal disorders (amenorrhea, oligomenorrhea) which are made by intensive and top level physical activities, increase indirectly the bone remodeling and decrease the bone mass. The effects of a moderate physical activity are more discussed. Nevertheless, an increasing of the bone mass peak is admitted. In the adult and postmenopausal women, the data are more uncertain and discussed. But, an adapted moderate regular physical activity for each people authorizes certainly a bone gain. It is favorable to prevent osteoporosis, its fractures and reduce the social cost.