Morphometry and calcium contents in appendicular and axial bones of exercised ovariectomized rats

To determine the effects of exercise and ovariectomy on calcium status in selected appendicular and axial bones, female Sprague-Dawley (8-9 mo) rats were assigned to groups based on the following combinations: control (C) or ovariectomized (O); sedentary (S) or exercised (E); and length of treatment (2 or 4 mo). Exercise consisted of treadmill running for 1 h/day, 5 days/wk at a speed of 14.1 m/min and 8 degrees elevation. After death, femurs, tibia-fibula complexes, ribs (T7), and vertebrae (T7) were excised, cleaned, and weighed, and selected morphometrics were measured. Tensile strength was measured for the femurs, and all bones were then acid-hydrolyzed and calcium concentration determined spectrophotometrically. Bone [Ca2+] was significantly greater for CE and OE animals when compared with their sedentary counterparts (CS, OS). Within 4 mo calcium losses were evident in the femur and tibia of the ovariectomized animals, and the moderate exercise program was of insufficient intensity to alter this loss. The average stress to failure for femur from all groups was 1.13 +/- 0.11 N/m2. However, the effects of exercise appeared beneficial in the axial bones where [Ca2+] increased in the ovariectomized animals.