BACKGROUND: Human growth hormone (hGH) responds to bouts of exercise by increasing, while the insulin-like growth factor-I (IGF-I) responses are conflicting. METHODS: Twenty well-trained male cyclists completed a brief duration exercise (A: warm up+increasing workload until exhaustion, lasting 25 min) and a medium duration exercise (B: warm up+70-80%VO(2 max)+increasing workload until exhaustion, lasting 40 min). The immunoreactivity of plasma hGH, the IGF-I in its total and free fraction were measured before and at the end of the exercise, and the free/total IGF-I ratio response to the two cycling exercise bouts was examined. RESULTS: Both A and B demonstrated increased hGH (from 77+/-122 to 544+/-327 and 28+/-68 to 369+/-276 pmol/l respectively) and total IGF-I (from 67+/-10 to 70+/-10 and 55+/-14 to 61+/-15 nmol/l respectively). The free IGF-I was decreased only in A (from 0.38+/-0.16 to 0.32+/-0.14 nmol/l). Both A and B demonstrated a decreased free/total IGF-I ratio (from 0.57+/-0.30 to 0.46+/-0.22 and 0.61+/-0.37 to 0.52+/-0.29). CONCLUSION: Brief and medium duration physical exercise influences the hGH, the total and free IGF-I concentrations. The free/total IGF-I ratio was also influenced and it might be related to the GH/IGF system. Its investigation might be a way of studying the training condition.
BACKGROUND:Humangrowth hormone (hGH) responds to bouts of exercise by increasing, while the insulin-like growth factor-I (IGF-I) responses are conflicting. METHODS: Twenty well-trained male cyclists completed a brief duration exercise (A: warm up+increasing workload until exhaustion, lasting 25 min) and a medium duration exercise (B: warm up+70-80%VO(2 max)+increasing workload until exhaustion, lasting 40 min). The immunoreactivity of plasma hGH, the IGF-I in its total and free fraction were measured before and at the end of the exercise, and the free/total IGF-I ratio response to the two cycling exercise bouts was examined. RESULTS: Both A and B demonstrated increased hGH (from 77+/-122 to 544+/-327 and 28+/-68 to 369+/-276 pmol/l respectively) and total IGF-I (from 67+/-10 to 70+/-10 and 55+/-14 to 61+/-15 nmol/l respectively). The free IGF-I was decreased only in A (from 0.38+/-0.16 to 0.32+/-0.14 nmol/l). Both A and B demonstrated a decreased free/total IGF-I ratio (from 0.57+/-0.30 to 0.46+/-0.22 and 0.61+/-0.37 to 0.52+/-0.29). CONCLUSION: Brief and medium duration physical exercise influences the hGH, the total and free IGF-I concentrations. The free/total IGF-I ratio was also influenced and it might be related to the GH/IGF system. Its investigation might be a way of studying the training condition.
Authors: Gwendolyn A Thomas; William J Kraemer; Brett A Comstock; Courtenay Dunn-Lewis; Carl M Maresh; Jeff S Volek Journal: Sports Med Date: 2013-09 Impact factor: 11.136
Authors: Matthew B Cooke; Paul La Bounty; Thomas Buford; Brian Shelmadine; Liz Redd; Geoffrey Hudson; Darryn S Willoughby Journal: J Int Soc Sports Nutr Date: 2011-11-08 Impact factor: 5.150
Authors: Maha Sellami; Wissem Dhahbi; Lawrence D Hayes; Johnny Padulo; Fatma Rhibi; Hanen Djemail; Anis Chaouachi Journal: PLoS One Date: 2017-08-11 Impact factor: 3.240