Performance of postural tasks by some of the same physiological constraints such as noise induced fatigue jeopardized. Mostly, to evaluate of Changes in postural control during fatigue traditional linear measures is used and little is known about the nonlinear dynamics of postural sway under this these conditions and its relationship with the level of skill. In this study, recurrence quantification analysis (RQA) for comparison nonlinear dynamics of postural sway three groups of students (n = 12), novice shooters (n = 6) and Skilled shooters (n = 6) is used. Change of center of pressure participants in 2 trials before and after isometric fatigue intensity of 40% - 60% - 70% - 80% MVC was recorded. The parameter median of data EMG and Borg scale of perceived fatigue was used as an indicator of fatigue. To determine the effect of fatigue on the variability variables, analysis of variance with repeated measures was used. The results showed that fatigue had significant effect on the value of the total variability, while the values of recurrence rate, deterministic structure and trend of both directions mediolateral and anteroposterior in 3 groups significantly from %70 of fatigue increase. It Seems that Fatigue can affect underlying structure of postural maintain task as a control parameters and this effect will not be influenced by the proficiency. However, the main effect of group is indicative of more skilled athlete’s adaptability in the face of fatigue to maintain optimal performance
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