Impact of a 12 week resistance and concurrent training on bone mechanical strength and mineral density of osteoporotic male Wistar rats

This study evaluated the efficacy of concurrent training compared to resistance training on femoral bone mineral density (BMD) and mechanical strength of osteoporotic male rats.
Eight out of 40 male Wistar rats were separated as healthy subjects. Then osteoporosis was induced in the remaining rats by the injection of ethanol (20%, i.p) for 3 weeks. Osteoporotic rats divided into 4 groups: Baseline, Resistance training, Concurrent training and Control. The resistance training protocol consisted of 8 series of climbs on a 110-cm vertical ladder angled at 80º with weights tied to the animal tail. The overload for first and eighth series was set at 50% and 100% of the total body mass of the animal, respectively. Concurrent group completed a combination of both resistance and endurance treadmill trainings (60 min/day, speed: 12 m/min). The left excised femur of the animals were scanned for BMD measurement and examined by three point bending test to obtain the maximum force and stiffness.
Two Resistance training and Concurrent training groups had significantly increased maximum force, stiffness and BMD compared to Control group (P=0.019). Compared to resistance group, the Concurrent group showed a positive effect on bone mechanical strength (P=0.039) with no significance difference in BMD (P=0.890).
The results of this study shows that the combination of resistance and endurance exercise may have a synergistic effect on increasing the mechanical strength of osteoporotic femoral bone in male rats compared to resistance training alone.