Viru A, Viru M, Karelson K, Janson T, Siim K, Fischer K, Hackney A C
Institute of Exercise Biology, University of Tartu, Tartu, Estonia.
Eur J Appl Physiol. 2007 May;100(2):241-5. doi: 10.1007/s00421-007-0416-9. Epub 2007 Mar 3.
This study evaluated the influence of adrenergic factors on the cortisol response to maximal exercise in endurance-trained men. This was achieved by testing healthy young men during exercise while varying both the condition of beta-adrenergic blockage and the presence of a well-controlled simulated competitive environment to simulate activity of the sympatho-adrenal systems. Subjects (n = 10) performed maximal exercise (running) to exhaustion on a treadmill during four conditions: (1) placebo non-competitive [PNon] (2) after administration of 80 mg propranolol non-competitive [betaNon] (3) in a simulated competition after a placebo intake [PCom], and (4) in a simulated competition after propranolol intake [betaCom]. Blood samples were obtained before (pre-) and 3 min after (post-) exercise and assayed for cortisol (C). The data were analyzed with a multi-factorial repeated measures ANCOVA procedure. Statistical analysis revealed a significant three-way interaction for the drug versus competition versus sampling time effects (P < 0.05). Post-hoc tests revealed that the pre-exercise cortisol values did not differ significantly among the conditions. Cortisol did increase from pre- to post-exercise in all experimental conditions (P < 0.01), and the magnitudes of increase in the PCom, betaNon and betaCom conditions were greater than that of the PNon condition. Furthermore, the cortisol increases for both beta-blockage conditions post-exercise (betaNon, betaCom) did not differ from one another (P > 0.05). The findings suggest beta-adrenergic blockage and competitive conditions enhance the exercise cortisol response. In combination, however, these conditions do not act in an additive fashion. This suggests that perhaps there may be two separate influences or mechanisms (i.e., excitatory, inhibitory) on the adrenergic control of adrenocortical function, or a sympathetic compensation for beta-blockage during exhaustive maximal exercise. Furthermore, the data suggests a possible "ceiling" on the hypothalamic-pituitary-adrenal axis response to exercise in endurance-trained men.
本研究评估了肾上腺素能因素对耐力训练男性最大运动时皮质醇反应的影响。这是通过在运动期间对健康年轻男性进行测试来实现的，同时改变β-肾上腺素能阻滞状态以及精心控制的模拟竞争环境的存在情况，以模拟交感-肾上腺系统的活动。受试者（n = 10）在四种情况下在跑步机上进行最大运动（跑步）直至 exhaustion：（1）安慰剂非竞争 [PNon]；（2）服用 80 mg 普萘洛尔后非竞争 [βNon]；（3）服用安慰剂后在模拟竞争中 [PCom]；以及（4）服用普萘洛尔后在模拟竞争中 [βCom]。在运动前（pre-）和运动后 3 分钟（post-）采集血样，并测定皮质醇（C）。数据采用多因素重复测量协方差分析程序进行分析。统计分析显示，药物、竞争和采样时间效应存在显著的三因素交互作用（P < 0.05）。事后检验显示，运动前皮质醇值在各情况下无显著差异。在所有实验条件下，皮质醇从运动前到运动后均有增加（P < 0.01），且 PCom、βNon 和 βCom 条件下的增加幅度大于 PNon 条件。此外，运动后两种β-阻滞条件下（βNon，βCom）的皮质醇增加彼此无差异（P > 0.05）。研究结果表明，β-肾上腺素能阻滞和竞争条件会增强运动时的皮质醇反应。然而，这些条件联合起来并非以相加的方式起作用。这表明，可能存在两种独立的影响或机制（即兴奋性、抑制性）对肾上腺皮质功能的肾上腺素能控制产生作用，或者在力竭性最大运动期间对β-阻滞存在交感神经补偿。此外，数据表明耐力训练男性下丘脑-垂体-肾上腺轴对运动的反应可能存在一个“上限”。
