Effects of exercise on bone growth mechanical and physical properties studied in the rat.

Thirty-four pubescent male rats were divided into exercise and control groups to examine the effects of a 1-month intensive exercise programme on the mechanical, physical (group 1) and histological properties (group 2) of the tibia and femur. At the completion of training, rats were sacrificed and the right hind-limbs dissected and stored at -60°C prior to torsional-testing at a speed of 180/s. Left tibiae and femora were measured for length and weight' Values for the width of the epiphyseal plate were also obtained from animals in group 2. Following the exercise programme the tibiae showed significant reductions in energy absorbed to failure, bone length and width of the proximal epiphyseal plate. No change was observed for the mechanical properties of the femora, but significant reductions occurred in bone length and weight.