The effect of physical activity on the properties of bone tissue

The effect of sports training or lack of physical activity on the properties of bone tissue is investigated. People with normal physical activity, sportsmen, and hypodynamic persons are tested. Ultrasound as a safe and noninvasive method is used. In normal activity and after short-time sports training or bed rest, the maximum ultrasound velocity is observed in the middle part of the tibia diaphysis because this region has the highest bending moment. Long-time sports training (more than seven years) in basketball and freestyle skiing alters the distribution of ultrasound velocity along the tibia: the maximum velocity is found in the distal diaphysis of the tibia due to the existence of high mechanical stresses in this region caused by the intense external impact loads and the calf muscle contraction. The maximum velocity for rowers is in the middle diaphysis or in the region between the proximal and middle diaphysis, since high impact loads are not characteristic of their foot joints. Long-time hypodynamia weakens the distal diaphysis of the tibia due to the lack of naturally occuring high stresses in this part of the bone.