Schmidt W, Doré S, Hilgendorf A, Strauch S, Gareau R, Brisson G R
Institut für Sportmedizin, Freie Universität Berlin, Germany.
Eur J Appl Physiol Occup Physiol. 1995;71(5):424-30. doi: 10.1007/BF00635876.
The response of plasma insulin-like growth factor I (IGF I) to exercise-induced increase of total human growth hormone concentration [hGHtot] and of its molecular species [hGH20kD] was investigated up to 48 h after an 1-h ergometer exercise at 60% of maximal capacity during normoxia (N) and hypoxia (H) (inspiratory partial pressure of oxygen = 92 mmHg (12.7 kPa); n = 8). Lactate and glucose concentrations were differently affected during both conditions showing higher levels under H. Despite similar maximal concentrations, the increase of human growth hormone (hGH) was faster during exercise during H than during N[hGHtot after 30 min: 8.6 (SD 11.4) ng.ml-1 (N); 16.2 (SD 11.6) ng.ml-1 (H); P < 0.05]. The variations in plasma [hGH20kD] were closely correlated to those of [hGHtot], but its absolute concentration did not exceed 3% of the [hGHtot]. Plasma IGF I concentration was significantly decreased 24 h after both experimental conditions [N from 319 (SD 71) ng.ml-1 to 228 (SD 72) ng.ml-1, P < 0.05; H from 253 (SD 47) to 200 (SD 47) ng.ml-1, P < 0.01], and was still lower than basal levels 48 h after exercise during H [204 (SD 44) ng.ml-1, P < 0.01]. Linear regression analysis yielded no significant correlation between increase in plasma [hGHtot] or [hGH20kD] during exercise and the plasma IGF I concentration after exercise. It was concluded that the exercise-associated elevated plasma [hGH] did not increase the hepatic IGF I production. From our study it would seem that the high energy demand during and after the long-lasting intensive exercise may have overridden an existing hGH stimulus on plasma IGH I, which was most obvious during hypoxia.
研究了在常氧（N）和低氧（H）（吸入氧分压 = 92 mmHg（12.7 kPa）；n = 8）条件下，进行1小时最大功率60%的测力计运动后48小时内，血浆胰岛素样生长因子I（IGF I）对运动诱导的总人生长激素浓度[hGHtot]及其分子形式[hGH20kD]增加的反应。在两种条件下，乳酸和葡萄糖浓度受到不同影响，在低氧条件下水平更高。尽管最大浓度相似，但低氧运动期间人生长激素（hGH）的增加比常氧期间更快[30分钟后hGHtot：8.6（标准差11.4）ng.ml-1（N）；16.2（标准差11.6）ng.ml-1（H）；P < 0.05]。血浆[hGH20kD]的变化与[hGHtot]密切相关，但其绝对浓度不超过[hGHtot]的3%。两种实验条件后24小时，血浆IGF I浓度均显著降低[N从319（标准差71）ng.ml-1降至228（标准差72）ng.ml-1，P < 0.05；H从253（标准差47）降至200（标准差47）ng.ml-1，P < 0.01]，且低氧运动后48小时仍低于基础水平[204（标准差44）ng.ml-1，P < 0.01]。线性回归分析显示，运动期间血浆[hGHtot]或[hGH20kD]的增加与运动后血浆IGF I浓度之间无显著相关性。得出的结论是，运动相关的血浆[hGH]升高并未增加肝脏IGF I的产生。从我们的研究来看，长时间高强度运动期间及之后的高能量需求可能超过了现有的hGH对血浆IGF I的刺激，这在低氧期间最为明显。
