Effects of Different Types of Jump Impact on Trabecular Bone Mass and Microarchitecture in Growing RatsReport as inadecuate




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Substantial evidence from animal studies indicates that jumping increases bone mass and strength. However, most studies have focused on the take-off, rather than the landing phase of jumps. Thus, we compared the effects of landing and upward jump impact on trabecular bone mass and microarchitecture. Male Wistar rats aged 10 weeks were randomly assigned to the following groups: sedentary control CON, 40-cm upward jumps 40UJ; 40-cm drop jumps 40DJ; and 60-cm drop jumps 60DJ n = 10 each. The upward jump protocol comprised 10 upward jumps-day, 5 days-week for 8 weeks to a height of 40 cm. The drop jump protocol comprised dropping rats from a height of 40 or 60 cm at the same frequency and time period as the 40UJ group. Trabecular bone mass, architecture, and mineralization at the distal femoral metaphysis were evaluated using microcomputed tomography. Ground reaction force GRF was measured using a force platform. Bone mass was significantly higher in the 40UJ group compared with the DJ groups +49.1% and +28.3%, respectively, although peak GRF −57.8% and −122.7%, respectively and unit time force −21.6% and −36.2%, respectively were significantly lower in the 40UJ group. These results showed that trabecular bone mass in growing rats is increased more effectively by the take-off than by the landing phases of jumps and suggest that mechanical stress accompanied by muscle contraction would be more important than GRF as an osteogenic stimulus. However, the relevance of these findings to human bone physiology is unclear and requires further study.



Author: Yong-In Ju , Teruki Sone, Kazuhiro Ohnaru, Kensuke Tanaka, Hidetaka Yamaguchi, Masao Fukunaga

Source: http://plos.srce.hr/



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