Effect of physical activity on bone mass.

Maintenance of bone mass depends on several factors, including proper level of physical activity, hormones, and nutrition. Prescribing effective weight-training and weight-bearing exercise programs for improving bone mass is highly desirable. Specificity of each exercise program can contribute to an increment or reduction of bone mass. Cessation of physical activity induces rapid metabolic bone changes, although the effects on bone mass take time to develop. Therefore, weight-bearing and periodic high-intensity loading exercises are recommended for maintenance of bone mass in the spine and lower extremities. Patients who endure a period of immobility such as prolonged bed rest should resume their daily activities in addition to supervised exertional exercises. While research continues in an effort to find ways to increase bone mass despite aging and negative genetic factors, more focus can be given to building a solid skeletal foundation through good nutritional and exercise habits developed early in life.