Age and Exercise as Factors Influencing Osteoporosis,Bone Strength,and Acceleration Tolerance.

摘要

Spinal injury associated with escape from high performance aircraft has tended to occur more frequently in the aged than the younger aircrewman population. Although an age influence for this trauma has not been clearly demonstrated,it must be hypothesized. Osteoporosis is part of the normal aging process and accompanies most diseases affecting man. Disuse osteoporosis appears to be an exaggeration of the normal aging process. Mechanical stress,such as that produced by exercise and physical activity,is necessary for the retention of skeletal mass and may be a specific influence in controlling the adverse effects of osteoporosis. Previous studies confirmed that inhibition of dynamic mechanical stress removes some of the stimuli necessary for normal skeletal modeling activity. The lack of musculoskeletal activity,weight bearing,or both result in a wasting away of bony elements (which seems to be a function of body position with respect to the gravitational vector). The quantity of hard tissue per unit volume decreases,general asthenia of the muscular system develops along with a marked decrease in the breaking strength of isolated vertebral motor segments. (Author)