Nemet Dan, Connolly Peter H, Pontello-Pescatello Andria M, Rose-Gottron Christie, Larson Jennifer K, Galassetti Pietro, Cooper Dan M
Center for the Study of Health Effects of Exeercise in Childdren, University of California Children's Hospital, College of Medicine, Irvine, CA 92868, USA.
J Appl Physiol (1985). 2004 Jan;96(1):276-82. doi: 10.1152/japplphysiol.00654.2003. Epub 2003 Aug 29.
Circulating IGF-I is correlated with fitness, but results of prospective exercise training studies have been inconsistent, showing both increases and decreases in IGF-I. We hypothesized that energy balance, often not accounted for, is a regulating variable such that training plus an energy intake deficit would cause a reduction in IGF-I, whereas training plus energy intake excess would lead to an increased IGF-I. To test this, 19 young, healthy men completed a 7-day strenuous exercise program in which they were randomly assigned to either a positive energy balance [overfed (OF), n = 10] or negative energy balance [underfed (UF), n = 9] group. IGF-I (free and total), insulin, and IGF-binding protein-1 were measured before, during, and 1 wk after the training. Weight decreased in the UF subjects and increased in the OF subjects. Free and total IGF-I decreased substantially in the UF group (P < 0.0005 for both), but, in the OF group, IGF-I remained unchanged. The UF group also demonstrated an increase in IGF-binding protein-1 (P < 0.027), whereas glucose levels decreased (P < 0.0005). In contrast, insulin was reduced in both the OF and UF exercise-training groups (P < 0.044). Finally, within 7 days of the cessation of the diet and training regimen, IGF-I and IGF-binding protein-1 in the UF group returned to preintervention levels. We conclude that energy balance during periods of exercise training influences circulating IGF-I and related growth mediators. Exercise-associated mechanisms may inhibit increases in IGF-I early in the course of a training protocol, even in overfed subjects.
循环中的胰岛素样生长因子-I（IGF-I）与体能相关，但前瞻性运动训练研究的结果并不一致，IGF-I水平既有升高也有降低。我们推测，常未被考虑的能量平衡是一个调节变量，即训练加能量摄入不足会导致IGF-I降低，而训练加能量摄入过量会导致IGF-I升高。为了验证这一点，19名年轻健康男性完成了一项为期7天的高强度运动计划，他们被随机分为正能量平衡组[过度喂养（OF），n = 10]或负能量平衡组[喂养不足（UF），n = 9]。在训练前、训练期间和训练后1周测量IGF-I（游离和总）、胰岛素和IGF结合蛋白-1。UF组受试者体重下降，OF组受试者体重增加。UF组游离和总IGF-I均大幅下降（两者P < 0.0005），但OF组IGF-I保持不变。UF组IGF结合蛋白-1也升高（P < 0.027），而血糖水平下降（P < 0.0005）。相比之下，OF组和UF组运动训练后的胰岛素均降低（P < 0.044）。最后，在停止饮食和训练方案的7天内，UF组的IGF-I和IGF结合蛋白-1恢复到干预前水平。我们得出结论，运动训练期间的能量平衡会影响循环中的IGF-I和相关生长介质。即使在过度喂养的受试者中，运动相关机制也可能在训练方案早期抑制IGF-I的升高。
