Abstract
Effects of forced running exercise on serial cross-sectional properties along the diaphysis of femur were studied in growing male rats. From 30 to 110 days of age, exercise group was trained to run for 20 minutes a day at a maximum speed of about 40m/min on a newly devised treadmill which seemed to burden the rat with minimal stresses. The cross-sectional properties varied with characteristic patterns along the femoral diaphysis from proximal to distal. The forced running exercise had the following effects on the cross-sectional properties in the proximal half of the femoral diaphysis; internal rotation of the principal axis, i. e. the direction of the maximum area moment of inertia; flattening of the cross-section so that its diameter was greater along the principal axis; increase in the cross-sectional area, area moment of inertia, and polar moment of inertia, which indicatesstrength of the femoral diaphysis against axial, bending, and torsional load, respectively.
