| Summary: | 碩士 === 國立臺灣體育大學 === 運動健康科學系碩士班 === 97 === Multi-day cycling events had gaining popular among recreational riders in Taiwan. The adaptation effect on bone metabolism has previously reported but mechanisms remain uncertain. The purpose of this study is to reveal the possible dominate factor of bone metabolism changes during a multi-day cycling event. Thirty previous untrained healthy subjects（24 males and 8 females, 19-38 years old）were recruited form participants of 2008 cycling tour of Taiwan. The tour covered approximately 1100 km in 15 days. Fasting blood samples were collected in the early morning on day 1, 5, 10, 15 during the tour and 5 days after the tour. Plasma OPG, sRANKL level was analyzed by ELISA, and PTH, Testosterone, Cortisol, Total PINP, Beta-crosslaps, and Osteocalcin were determined by electrochemiluminescence immunoassay, respectively. Serum Bone-specific alkaline phosphatase were determined by HITACHI-7020 automatic analyzer. PTH level were slightly increased on day 10 and were significantly on day 15. Testosterone level were decreased on day 5 and returned to basal level since day 10. Cortisol level were not significantly changed through out the journey. OPG level were significantly higher compared with basal level. sRANKL level were reduced through the journey. Total P1NP level were reduced on day 5 but returned to basal level on day 10 and significantly higher than basal level on day 15. Beta-crosslaps were reduced on day 5 and then returned to basal level after day 10. Osteocalcin level were reduced on day 5 and then returned to basal level after day 10. Bone-specific alkaline phosphatase level were significantly reduced through out the journey compared to basal level. Results of current study suggested that multi-day cycling tour induced significant adaptation effect which mediated through sRANKL/OPG transduction pathway on bone metabolism. Down-regulation of OPG expression by increased Testosterone level under prolonged exercise stimulation may possibly responsible for the adaption effect of bone metabolism on untrained subjects.
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