The aim of this study was to compare the short-term effect of Creatine,Beta-Alanine, combine Creatine-BetaAlanine on peak torque, time to peak and torque development of knee extensor muscles in speeds of 60 and 180 degree/seconds. torque parameters of 40 healthy university athletes dominant leg knee extensors in angular velocity of 60 and 180 degrees per second in the isokinetic machine in 40 subjects in the pre-test and post-test were measured. Analysis of covariance was used to data analysis. No significant changes in peak torque, time to peak and torque development of knee extensor muscles after short-term use of Creatine,Beta-Alanine, combine Creatine*Beta-Alanine at any rate in speeds of 60 and 180 degrees per second. shortterm consumption (5 days) of Creatine, Beta-Alanine, combine Creatine*BetaAlanine cannot lead to peak torque, time to peak and torque development of knee extensor muscles in speeds of 60 and 180 degrees per second improvement. Introduction Creatine and Beta-Alanine has become a popular nutritional supplement among athletes. Short-term creatine supplementation has been reported to improve maximal power/ strength; work performed during sets of maximal effort muscle contractions, single-effort sprint performance, and work performed during repetitive sprint performance(1-3) Recently, attempts have been made to enhance the effects of creatine by adding β-alanine to its formula. β-alanine, an amino acid derivative, has been shown to increase carnosine concentrations within skeletal muscle(6). Carnosine has been shown to enhance the buffering capacity during high-intensity exercise(5). Although creatine supplementation alone has been shown to improve fatigue rates in anaerobic exercise(7), additional benefits supplied by β-alanine may further reduce the rate of fatigue in muscle providing for a greater training stimulus. The endocrine system has been shown to respond to changes in exercise intensity, volume, and rest(8). Considering that creatine supplementation is thought to improve the quality of the workout, it may have important implications to endocrine function and influence on muscle remodeling. Although limited research has indicated that creatine supplementation does not influence the acute responses to an exercise stress(4,7), its’ ability to change resting hormonal concentrations is less understood. Volek and colleagues have indicated that alterations in resting hormonal concentrations are unable to explain performance and body composition changes during a 4 wk resistance training program(11). However, the aim of this study was to compare the short-term effect of Creatine, Beta-Alanine, combine Creatine*Beta-Alanine and amount of consumption on peak torque, time to peak and torque development of knee extensor muscles in speeds of 60 and 180 degree/seconds. Methods 40 active healthy subjects without disease and the lack of any special diet or taking any type of supplement voluntarily were selected to participate in the study. After explanation of the study objectives and complete the consent form, the subjects were randomly divided into five groups: creatine(n=8), placebo(n=8), beta-alanine(n=8), or placebo(n=8) and control(n=8). All participants signed an informed consent form before participating in the study. Ethics approval center for study was Tehran medical university that this center ethic review board previously reviewed the study protocol and then study were done. Subjects were familiarized with the isokinetic device and several times were trained the isokinetic test conditions and repeated the knee extension with maximum power. Three days later than the subject’s familiarization with the testing, the subjects’ height and weight measured with a digital scale and stediometer Model Es-1200 respectively and the pre test of biodex isokinetic Pro. 3 were taken. To obtain parameters related to the torque of the knee extensor muscles the dominant leg(a foot which subject strikes the ball), isokinetic machine was set so that each subjects performed knee extension at angular velocities of 60 and 180° per second six times with a maximal power. Creatine supplementation was performed on 5 consecutive days. Placebo group received glucose supplements as placebo. The betaalanine Supplement consumed as a capsules three times daily along with major meals by the experimental group. Finally, the post test of the knee extensor muscle torque was done in speeds of 60 and 180 degree per second immediately days after the end of supplementation. The covariance analysis used for statistical analysis in alpha level at ≤0.05 in SPSS program version 16. Results Means and standard deviations of demographic characteristics in studied groups are shown in table 1. Table1. Means and standard deviations of demographic characteristics in studied groups. Weight(kg) Height(cm) Age(years) 76.46±12.23 178.73±3.34 19.78±1.12 Creatine 77.44±15.69 179.66±8.62 18.26±3.55 Beta-Alanine 78.46±15.23 178.11±3.34 18.00±2.06 combine Creatine *Beta-Alanine 76±12.03 179.73±8.34 19.00±3.23 Placebo 77.06±15 178±3.04 17.71±1.32 Control Covariance analysis results for supplements effect on peak torque in speeds of 60 and 80 degree are shown in table 2 respectively.