VUeut iyerisindeki metaboliklerle bir ili~ki iyindcbulunan yOl'gunlnk, performansm sInJrlayJCl faktorUdiir.Yorgunluk oldukya kompleks bir kavram olarakkaqJmlZa yJkmaktadlr. Bu kavramln hem fizyolojik hem depsikolojik bir boyutunun da oldugu bilinmektedir. Sporlifaktiyjteler slrasmda vUcudun sistemlerine dii~en awrl1ktayapllan aktivitenin Wrtine gorc artmaktadlr.Yorgunlukta, j~i yapan kaslar kadar bunlan hal'ekelege<;iren sinir sisteminin de roW yok bUyiikttir.Yorgunlugun olu~um scbeplerini iki ana ba~hktatoplayabiliriz.1-Metabolik Sebepler: Kastaki fosfokreatinkonsantrasyonunun tUkenmesi, kaslarda proton birikimi,glikojenin kan ve kastaki miktannda azalmaJtLikenmesi,plazmadaki serbest LripLofan oranlnlO aminoasitkemiklerinin oranwa yUkselmesi. sinir kas noktalan vesinapslarda gereksiz asetilkolin (Ach) sentai, beyin sinirhticrelerinin yorgunlugu, kandaki kaLekolaminlerinmiktanndaki azalma, elektron ve su kayhl.2- Psiko-Sasyal Sebcpler: Ki~isd faktorler,psikolojik faktorler ve <;evresel faktorler.Anahtar KelimeJer : Yorgunluk, ATP, Cpo SummaryFatJgue has acted negative on performance and it isrelation in the body metabolics. FatIgue is complex eoneeptfor this reason this concept has psychological andpysiological dimensions.The responsibility of body systems chaneesaceording !b selected sports. Nerve system has animportant role in falJgue as body muscles since ifstimulates them.There are two different reasons for fatlgue:1· Metabolic Reasons : concentration ofphosphocreatine in exhausted in tbc 'muscle, accumulationof proLon in the muscle, the decrease of glieojen level in theblood. and muscle. tbe increase of the free triptophan levelunLil] amino acid bone level, unnecessry synthesisacetilcholin (Ach) in the synaps and the point of nervemuscle, the reduction of catekolamine level in the blood,dehidration and losses of the electrons.2- Psycho-Social Reasons ; Personnel factors,psycbological factors, psychological factors andenviromental factors.Key Words; Fatigue, ATP, Cpo