Effects of physical training on bone adaptation in three zones of the rat tibia

Abstract

This study as been conducted to examine the effects of physical exercise on the bone trabecular network and the cellular adaptations in three different areas of a single bone, the tibia. Male Wistar rats (9 weeks old) were treadmill-trained for 0, 3, 4, or 5 weeks at 60% of their measured maximal O2 consumption (VO2max). Histomorphometric analysis of the proximal tibia of running and age-matched control groups was performed in the epiphyseal trabecular bone, in the primary spongiosa and in the secondary spongiosa. Dynamic and static bone cell activities and serum calcium and phosphorus levels were measured. VO2max increased significantly by 18.4% after 5 weeks of training. In the epiphysis, a 9% increase in bone volume, associated with more numerous trabeculae (8%) was detected the third week of training. In primary spongiosa a significant increase (6.7%) in newly formed trabeculae was found. In secondary spongiosa bone volume increased significantly by 26.2% the fifth week of exercise and was associated with thicker trabeculae. The number of osteoclast profiles was significantly depressed. Osteoid surfaces and bone formation rate increased significantly in weeks 3 to 5. Serum calcium levels were found to be significantly decreased in weeks 3 and 4. There was no change in osteoid thickness or mineral apposition rate. These results suggest 1) a rapid increase in osteoblastic recruitment without change of the cell activity in response to moderate exercise; 2) a decreased bone resorption associated with a marked increased in bone formation from the third week of training; 3) adaptation of the trabecular network to exercise that seems to be bone-site-dependent, suggesting a cell sensitivity to training-engendered strain distribution within the bone or to strain-related local factors.

The effect of two types exercise therapy on bone mineral density and mechanical strength of osteoporotic male rats

“…Furthermore, the present results are consistent with Iwamoto (2009) and Joo (2013) findings, regarding the increase of femur BMD and the no increase in L4+L5 BMD. In contrast, the result of Borin (2010) study regarding the destructive effect of 11 weeks running on the treadmill with high intensity on skeleton system (25) and also Yoshinobu results show decrease in bone tissue of long bone due to 180 minute exercise on treadmill are not consistent with our study. Shimegi stated that intensity and duration of exercise are effective on increasing BMD.…”

Exercise and Bone Mass in Adults

“…[74] Experiments with rats have shown that running has osteogenic effects on loaded bones of young male [75] and female [76,77] rats, as well as in ovariectomized [78] and orchidectomized rats, [79] although the osteogenic effect of exercise appears to be less efficient in female ovariectomized rats. [78] The forces generated during running play a role in the osteogenic response, since the rats that run with a loaded backpack on top of their back show a greater gain in bone mass than the rats running without extra load.…”

“…Studies performed in our laboratory have reported that adult (19-27 years old) amateur male Exercise and Bone Mass in Adults 443 [75] (1995)…”

The Effects of Endurance Running Training on Young Adult Bone: Densitometry vs. Biomaterial Properties

“…In these studies, the exercise groups revealed significantly less BW gain after a programmed ERT. [50][51][52][53][54][55] With lower BW, exercise trained animals showed no difference or lower BMD values as compared to the sedentary control group. As in human subjects, male rats undergoing intense ERT exhibit lower BW gain and no benefits to bone health when considering BMD or BMC as a predictor.…”