Effects of Exercise Training on Weight-bearing Bone Loss during 30 d -6Head-down Bed Rest

LIU Yu-sheng; WU Bin; FEI jun; TAN Cheng; ZHAO Dong-ming; SUN Hong-yi; GU Zhi-ming; WU Ping; LIU Xing-hua; WANG Jun; ZHONG Chong-fa; GENG Jie; SUN Xi-qing

Abstract：Objective To observe the protective effects of the lower limb muscular strength exercise training and the bicycle ergometer exercise training method on weight-bearing bone loss during 30 d - 6°head-down bed rest (HDBR) , and screening available exercise training method for space flight astronauts exposed to space microgravity. Methods Fifteen men were divided into three groups, control group (A ) , lower limb muscular strength exercise training group (B) and bicycle ergometer exercise training group ( C) , with 5 in each group. The both exercise groups were conducted 25 times exercise training during 30 d -6°HDBR. B group was 16 -18 min everyday, and C group 30 min. The exercise training was carried out in -6°head down tilt supine position. Before and after 30 d -6°HDBR, the whole body bone mineral density ( BMD QDR4500/W Ho-logic) , whole body bone mineral content (BMC) , and lumbar spine trabecular ratio ( CT Philips-Mx-8000) were measured. Results Compared with pre-HDBR, in group A;the left hip total BMD, the right hip trochan-ter BMD and the lumbar spine(2～4) trabecular ratio significantly decreased; in group C, even though whole body BMD increased significantly, the lumbar spine(3～4) BMD decreases significantly; in group B, the whole body BMD and weight-bearing bone BMD did not decrease significantly. Conclusion This study showes that the control group weight-bearing bone ie. lumbar spine and hip bone BMD significant decreased during 30 d -6°DBR, the bicycle ergometer exercise training methods even though whole body BMD increase significantly, but not maintain lumbar spine BMD during 30 d -6°HDBR, however, the lower limb muscular strength exercise training methods has significant protective effect on whole body and weight-bearing bone BMD during 30 d -6°HDBR. These study results provide valuable basis in fomulating counter-measures protocols for space flight astronauts exposed to space microgravity.