Interrupted resistance training and BMD in growing rats

A resistance training program, where the exercise was uninterrupted (UT, i.e. continuous repetitions) was compared against another resistance training program where the exercise was interrupted (IT, i.e. 2 exercise sessions during a training day) for enhancing bone modeling and bone mineral density (BMD) in maturating animals. The total volume of work performed between the two resistance training programs was equivalent by design. Young male rats (approximately 8 weeks old) were randomly divided into Control (Con, n=8), UT (n=8) and IT (n=7) resistance trained groups. The UT and IT groups were conditioned to climb a vertical ladder with weights appended to their tail 3 days/week for 6 weeks. After the 6 week training regimen (Mean+/-SD), tibial BMD (assessed via DXA) was significantly greater for UT (0.237+/-0.008 g/cm(2)) and IT (0.238+/-0.005 g/cm(2)) compared to Con (0.223+/-0.004 g/cm(2)). Further, serum osteocalcin (OC) was significantly greater for UT (45.65+/-2.83 ng/ml) and IT (46.33+/-4.60 ng/ml) compared to Con (37.86+/-4.04 ng/ml). There was no significant difference in BMD or serum OC between UT and IT groups. The results indicate that both resistance training programs were equally effective in elevating BMD in growing animals.