Impact of Resistance Training on Bone During 40% Caloric Restriction in Growing Female Rats

There is a growing trend in the use of severe caloric restrictive diets among normal weight young females that can jeopardize bone health. Using an animal model, the purpose of this study was to determine whether resistance training (RT) could maintain bone health during a 6-week severe caloric restrictive (CR) diet in growing female rats. Twenty-four female rats (~ 8 weeks old) were randomly divided into the following groups: sedentary rats fed a normal diet (N = 8), sedentary rats fed a 40% CR diet (D = 8), and an RT group fed a 40% CR diet (DT = 8). The DT group climbed a vertical ladder four consecutive times (per exercise session) with weights appended to their tail 3 days/week for a total of 6 weeks. Tibial bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry scans and bone mechanical properties were measured. After 6 weeks, the body mass (Mean ± SD) of CR-fed groups (D & DT = 202.8 ± 10.7 g) was significantly lower than N (275.5 ± 25.3 g). Tibial BMD (g/cm²) for D (0.196 ± 0.012) was significantly lower vs. N (0.213 ± 0.013), resulting in a 7.9% decline. The tibial BMD for DT (0.206 ± 0.009) resulted in a 3.3% decline compared to N that was not significantly different. Bone mechanical properties were significantly greater for DT compared to D, but not significantly different compared to N. Resistance training has the potential to maintain bone health during severe caloric restriction in growing female rats.