目的　探讨酪氨酸和依那普利对高原人体运动时自由基代谢的影响。　方法　对进驻海拔 3 70 0 m高原半年的 3 0名健康青年随机分为酪氨酸组、依那普利组及安慰剂组 ,每组 10人。在安静时、服药前、服药第 10天、第 15天及停药第 10天、第 2 0天分别采用功率自行车进行渐增负荷运动至力竭 ,测定其血清中超氧化物歧化酶 (SOD)、谷胱苷肽过氧化物酶 (GSH-Px)和丙二醛 (MDA)含量。　结果　 1高原力竭运动使 GSH-Px、MDA增加 (P<0 .0 5 ) ,SOD无统计学差异 (P>0 .0 5 )。2给予酪氨酸、依那普利 10 d即可使 SOD、GSH-Px活性增强 ,MDA降低 ;依那普利停药 10 d药效消失 ,酪氨酸停药 2 0 d药效消失。　结论　酪氨酸、依那普利对高原低氧所致的自由基代谢失衡均有调节作用 ,可提高高原作业效率 ,延缓运动性疲劳发生 ,且酪氨酸效果更适合 Objective To investigate the effects of tyrosine and enalapril on free radical metabolism during high altitude exercise. Methods Thirty healthy youths who were stationed at an altitude of 3 700 m were randomly divided into tyrosine group, enalapril group and placebo group, with 10 in each group. In the quiet, medication, medication on the 10th day, the first 15 days and the withdrawal of drug on the 10th day, the 20th day using power bicycles were gradually increased load exercise to exhaustion, serum superoxide dismutase (SOD) , Glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) content. The results showed that GSH-Px, MDA increased (P <0.05), SOD had no statistical difference (P> 0.05). 2 administration of tyrosine, enalapril 10 d can make SOD, GSH-Px activity increased MDA decreased; enalapril withdrawal 10 days disappeared efficacy tyrosine withdrawal 20 days disappeared. Conclusions Tyrosine and enalapril exert their effects on the imbalance of free radical metabolism induced by plateau hypoxia, which can improve plateau operating efficiency and delay exercise fatigue, and the tyrosine effect is more suitable