The present invention relates to a compound of Antrodia camphorata used to delay physiological fatigue, in particular to a extract isolated from Antrodia camphorata, 4-hydroxy-2,3-dimethoxy-6-methyl-5(3,7,11-trimethyl-dodeca-2,6-10-trienyl- )-cyclohex-2-enone, and its use in delaying fatigue. Immediate supplementation of the compound according to the invention after high intensity exhausted exercise at 80% VO.sub.2max can promote the metabolism of creatine phosphate kinase and blood ammonia in human bodies, be beneficial to their recovery, further achieves the function in delaying physiological fatigue.