Training-induced Increase in Bone Mineral Density between Growing Male and Female Rats

• Published in: International journal of sports medicine 2015-11, Vol.36 (12), p.992-998
• Main Authors: Joo, W., Singh, H., Ahles, C. P., Lee, Y., Colazas, W., Lee, L. C., Prakash, A., Jaque, S. V., Sumida, K. D.
• Format: Article
• Language: English
• Subjects: Animals; Body Weight; Bone Density - physiology; Female; Growth - physiology; Male; Models, Animal; Physical Conditioning, Animal - methods; Random Allocation; Rats, Sprague-Dawley; Resistance Training - methods; Sex Factors; Training & Testing
• ISSN: 0172-4622; 1439-3964
• DOI: 10.1055/s-0035-1555777

Abstract The purpose of this study was to determine the existence of sex differences in the resistance training-induced elevation in bone mineral density (BMD) and bone strength (Fmax) during the growth period in rats. 16 male (M) and 16 female (F) rats (approx. 8 weeks old) were randomly divided into sedentary control (MC=8, FC=8), and resistance-trained (RT) groups (M-RT=8, F-RT=8). The RT groups were conditioned to climb a vertical ladder 4 consecutive times (per exercise session) with weights attached to their tail 3 days per week for a total of 6 weeks. After 6 weeks, there were no interaction effects (sex×exercise). The main effect of sex indicated no difference in tibial BMD (in g/cm 2 ) for males (0.226±0.005) compared to females (0.221±0.004). However, Fmax (in Newtons) was significantly greater for males (131.3±5.3) compared to females (89.9±3.0). The main effect of exercise indicated that tibial BMD and Fmax were significantly greater for RT groups (0.234±0.004 g/cm 2 and 120.9±7.4 Newtons) compared to controls (0.212±0.003 g/cm 2 and 100.3±5.1 Newtons). The results indicate that during growth, there were no sex differences in the training-induced elevation in BMD and bone mechanical properties.