Open Access Research

Jump exercise during hindlimb unloading protect against the deterioration of trabecular bone microarchitecture in growing young rats

Yong-In Ju1*, Teruki Sone2, Kazuhiro Ohnaru2, Hak-Jin Choi3, Kyung-A Choi4 and Masao Fukunaga5

Author Affiliations

1 Department of Health and Sports Sciences, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, Okayama 701-0193, Japan

2 Department of Nuclear Medicine, Kawasaki Medical School, Kurashiki, Okayama, 701-0192, Japan

3 Graduate School of Medical Professions, Kawasaki University of Medical Welfare, Kurashiki, Okayama, 701-0193, Japan

4 Graduate School of Sport Science, Sungkyunkwan University, Suwon, Gyeonggi-Do, 440-746, Korea

5 Kawasaki Medical School, Kurashiki, Okayama, 701-0192, Japan

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SpringerPlus 2013, 2:35  doi:10.1186/2193-1801-2-35

Published: 31 January 2013

Abstract

Three-dimensional femoral trabecular architecture was investigated in tail-suspended young growing rats and the effects of jump exercise during the period of tail-suspension were also examined. Eight-week-old male Wistar rats (n = 24) were randomly assigned to three body weight-matched groups: a tail suspended group (SUS, n = 8); a sedentary control group (CON, n = 8) and rats primed with jump exercise during the period of tail suspension (JUM, n = 8). The jump exercise protocol consisted of 30 jumps/day, five days/week with a 40 cm jump height. After 3 weeks of jump exercise, bone mineral density (BMD) of the entire right femur was measured using dual energy X-ray absorptiometry. Three-dimensional trabecular bone architecture at the distal femoral metaphysis was evaluated using microcomputed tomography (micro-CT). Tail suspension caused a decrease in femoral BMD (−5%, p < 0.001) and trabecular bone architectural deterioration. Deterioration in the trabecular network during hindlimb unloading was mostly attributed to the reduction of trabecular number (−32%, p < 0.001) in the distal femoral metaphysis. Jump exercise during the tail suspension period increased trabecular thickness (14%, p < 0.001) and the reduction of trabecular number was suppressed. The present data indicate that jump exercise applied during hindlimb unloading could be able to inhibit bone loss and trabecular bone architectural deterioration caused by tail suspension.

Keywords:
Jump exercise; Tail suspension; Trabecular bone; Microarchitecture; Microcomputed tomography