Adaptation of cross-sectional morphology of the femoral diaphysis to exercise

The relationship between different modes of exercise and morphological features of the femoral cross section was investigated by conducting experiments on laboratory rats. Results were compared between bipedal standing exercises and quadrupedal running exercises with respect to cortical thickness around the circumference of ten serial cross-sections along the femoral diaphysis (80 points between 30-75% level) and the geometric properties of the same sections. In both modes of exercise, the cortical thickness increased mainly in the proximal and middle levels of the femur shaft, where changes of cross-sectional geometric properties occurred. In the quadrupedal running rats, cortical thickness was markedly increased around the third trochanter, the region where m. gluteus superficialis and m. adductor brevis insert and m. vastus lateralis arises. In contrast, in the bipedal standing rats, cortical thickness increased mainly around the postero-medial and antero-medial region of mid shaft, seemingly corresponding to the area where m, adductor longus and m. adductor magnus insert and m. vastus medialis arises, respectively. These results suggest that contractions of each hindlimb muscle primarily act as mechanical factors enhancing the regional cortical thickness, thus leading to the changes of cross-sectional geometry, and ultimately affects the whole morphology of the femoral shaft, together with the gravitational factor

Circumference · Diaphysis · Electromyography · Femoral neck · Femoral shaft · Femur · Geometry · Intramedullary rod · Lesser Trochanter · Osteoporosis · Physical medicine and rehabilitation · Quadrupedalism · Trochanter · Vastus medialis · Lower Extremity Biomechanics and Pathologies · Mathematics · Medicine · Sports injuries and prevention · Sports Performance and Training · Anatomy · Internal Medicine · Surgery