Abstract
[Purpose]This study aimed to investigate the effect of swimming exercise on high-fat diet-induced low bone mineral density (BMD) and trabecular bone microstructure in rats. [Methods]Eight-week-old male Sprague– Dawley (SD) rats were divided into a normal diet group (n = 9) and a high-fat diet group (n = 15). Three rats in each group were sacrificed after 8 weeks of high-fat diet to evaluate the association between high-fat diet and bone health. The other 18 rats were reassigned to 3 groups (normal diet control, NC; high-fat diet control, HC; high-fat diet + Exercise, HEx) for up to another 8 weeks. Rats in the exercise group were trained for a swimming exercise program (1 h/day, 5 times/ week for 8 weeks). All rats were sacrificed 24 h after the last bout of exercise to analyze the BMD and trabecular bone microstructure in the femur and tibia, using micro-computed tomography. [Results]First, the effect of high-fat diet on bone health was examined. It was observed that BMD, percent bone volume (BV/TV), and trabecular number (Tb.N) of the femur and tibia were lower in rats in the high-fat diet group than in those in the normal diet group (p < .05). In addition, BMD, BV/TV, and Tb.N of the femur and tibia were significantly increased in rats that underwent the 8-week swimming exercise program, compared to the corresponding values in rats in the HC group (p < .05). [Conclusion]These results indicate that high-fat diets negatively affect bone health; however, these negative effects can be improved by exercises such as swimming.
Highlights
Bones are active living tissues that are sensitive to external stimuli such as exercise and to metabolic changes within the body, and actively undergo metabolism[26]
Bone metabolism is regulated by the differentiation of marrow mesenchymal stem cells, which can differentiate into osteoblasts and adipocytes[6]
From childhood to early adulthood, which is the period of increase in bone mass, the differentiation of marrow mesenchymal stem cells into osteoblasts increases owing to the effects of growth factors; during the period of a decrease in bone mass as a result of aging, differentiation into osteoblasts decreases, while differentiation into adipocytes increases; this phenomenon inhibits normal bone metabolism[18]
Summary
Bones are active living tissues that are sensitive to external stimuli such as exercise and to metabolic changes within the body, and actively undergo metabolism[26]. Bone metabolism is regulated by the differentiation of marrow mesenchymal stem cells, which can differentiate into osteoblasts and adipocytes[6]. Excessive accumulation of fat, as observed in obesity, induces the expression of various inflammatory cytokines, and promotes the differentiation of marrow mesenchymal stem cells and hematopoietic stem cells into osteoclasts to increase bone resorption and decrease bone mineral density, increasing the risk of osteoporosis and fractures[20]. Sawant et al reported lower bone mineral density of the tibia and femur in rat models of high-fat diet-induced obesity than in normal rats[29]. This result indicates that high-fat diet-induced obesity has negative effects on bone mineral density
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
