Chinese Journal of Tissue Engineering Research ›› 2011, Vol. 15 ›› Issue (33): 6157-6160.doi: 10.3969/j.issn.1673-8225.2011.33.019

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Changes in bone mass, insulin-like growth factor 1, transforming growth factor β and interleukin 6 during long-term progressively increasing load training

Zheng Lu, Wang Zhi-qiang, Chen Xiao-hong   

  1. Capital Institute of Physical Education, Beijing 100088, China
  • Received:2011-04-04 Revised:2011-07-06 Online:2011-08-13 Published:2011-08-13
  • About author:Zheng Lu☆, Doctor, Professor, Capital Institute of Physical Education, Beijing 100088, China zhenglu@cipe.edu.cn
  • Supported by:

    a grant from Academic Innovation Team of Beijing Committee of Education, No. BJSJWRCTD-2007*

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Abstract:

BACKGROUND: Studies have demonstrated that a reasonable amount of regular exercise can increase bone mass and excessive exercise would influence the accumulation of bone mass. However, the precise mechanism underlying the effect of excessive exercise on bone metabolism remains poorly understood.
OBJECTIVE: To investigate the effect of long-term progressively increasing load training on bone mass and bone metabolism.
METHODES: Sprague-Dawley rats were given 4, 9, 11, 13, 15 and 17 weeks of progressively increasing load exercise. A control group was set. Estradiol level in each group was measured by radioimmunoassay and serum level of insulin-like growth factor 1 (IGF-1), transforming growth factor β (TGF-β) and interleukin 6 (IL-6) was determined by enzyme-linked immunosorbent assay. Bone mineral density in each group was determined by dual energy x-ray absorptiometry.
RESULTS AND CONCLUSION: Compared with the control group, IGF-1 and TGF-β levels were significantly decreased after 9 and 17 weeks of training (P < 0.05), TGF-β level was significantly increased after 4 weeks of training (P < 0.05), IL-6 level was significantly increased after 9, 15, and 17 weeks of training (P < 0.05), estradiol level was significantly decreased after 13, 15 and 17 weeks of training (P < 0.05 or P < 0.01), and bone mineral density was significantly decreased after 15 and 17 weeks of training (P < 0.01). Results showed that long-term progressively increasing load training resulted in bone metabolism changes from bone formation to bone absorption superiority and finally leaded to decrease in bone mineral density. The reasons of bone resorption superiority may be related to inhibition of sex gland axis and lower serum estradiol level.

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