High volumes of resistance exercise are not required for greater bone mineral density during growth.

Abstract

The purpose of this study was to determine the minimum amount of resistance exercise that would stimulate bone formation, via an elevation in bone mineral density (BMD), during the growth period in male rats. Forty male rats were randomly divided into control group (Con, n = 8), one ladder climb resistance-trained group (1LC, n = 8), two ladder climb resistance-trained group (2LC, n = 8), three ladder climb resistance-trained group (3LC, n = 8), and four ladder climb resistance-trained group (4LC, n = 8). All exercised groups were conditioned to climb a vertical ladder with weights appended to their tail 3 d·wk(-1) for a total of 6 wk. After 6 wk, left tibia BMD (mean ± SE) was significantly greater for 2LC, 3LC, and 4LC (0.233 ± 0.003 g·cm(-2)) when compared with Con (0.218 ± 0.003 g·cm). Left femur BMD was significantly greater for 2LC, 3LC, and 4LC (0.318 ± 0.003 g·cm(-2)) when compared with 1LC (0.299 ± 0.008 g·cm(-2)) and Con (0.289 ± 0.010 g·cm(-2)).There were no significant differences in BMD between 2LC, 3LC, and 4LC groups. The results suggest that during growth, a low amount of resistance exercise was just as effective as high volumes of strength training for stimulating bone modeling.