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n International SportMed Journal - Enhanced femoral neck strength in response to weightlifting exercise training in maturing male rats : original research article
Background : While the reduction of bone collagen content has been suggested to occur in bone loss during aging, the effects of weightlifting exercises on femoral neck strength and collagen content are not completely understood.
Research question : This study tested the effects of weightlifting exercise training on femoral neck mechanical and structural properties in maturing rats.
Type of study : Randomised controlled study.
Methods : Twelve-week-old male Wistar rats (initial body mass, 252 ± 14 g) were randomly divided into Control (CO, n = 7) and Trained (TR, n = 7) groups. Animals from the TR group were subjected to a resistance-training regime [five sessions·wk-1; four sets of 12 repetitions, 80% of one repetition maximum (1 RM), 90 s resting interval] for eight weeks. The femoral neck maximum load, stiffness and tenacity were measured. Bone mineral density (BMD) and mineral content (BMC), as well as the femoral neck bone volume (BV/TV) and collagen type I and III content were assessed.
Results : TR animals exhibited a higher (P < 0.05) femoral neck maximum load (117 ± 18 N vs. 99 ± 17 N), stiffness (151 ± 18 N/mm vs. 116 ± 17 N/mm), tenacity (67 ± 12 mJ vs. 61 ± 13 mJ), total collagen (32.83 ± 3.59% vs. 24.73 ± 5.89%) and collagen type III content (6.5 ± 4.1% vs. 0.6 ± 0.7%) than CO animals, respectively. No effects of exercise were observed on BV/TV, BMC, BMD and collagen type I content (P > 0.05).
Conclusion : Weightlifting exercise training enhances the femoral neck mechanical properties in maturing rats without increasing bone volume and mineral density, but with important augmentations in the total and type III collagen contents. This indicates that the improved femoral neck strength in response to weightlifting training is more likely to be due to bone quality as opposed to bone quantity.
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