Nickesh Mistry

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INTRODUCTION: Post activation Potentiation (PAP) is a new concept that has a need for further research. The performance of a muscle depends on the historic activity of that muscle. The concept of PAP is activating the muscle prior to maximal contraction. This concept works on the basis that the muscle has history of activating and, in turn, will be able to produce a greater force and torque. This idea was utilized with a biceps isometric contraction. An isometric contraction is a contraction where the joint angle as well as the muscle length is not going to change during the contraction. PURPOSE: The purpose of this study was to evaluate the effects of post activation potentiation on an isometric bicep contraction. METHODS: Eight male subjects (Age 21.9 ± 2.3 yrs; Weight 69.348 ± 9.7 in; Height 180.34 ± 12.3 lbs) from the University of Texas in Arlington volunteered to participate in this study. Each subject was asked to come into the biomechanics lab twice, once to become familiarized with the Biodex 3 machine and the second time to perform the experiment. Upon arriving at the Biomechanics lab for the experiment each subject was prepped with electromyography (EMG) electrodes. An electrode was placed on the ball of the right biceps and a ground was placed on the first cervical (C1) vertebrae of the spine. After the electrode placement the subject was then secured down into the seat of the Biodex machine. The right elbow rested on a pad with the arm at a 90 degree angle when holding the hand grip. The subject’s body was strapped down to reduce any additional movement and so the biceps would be isolated and the only muscle performing the contraction. There were three trials were taken in two different conditions, either the PAP condition or the non-PAP condition. In the PAP condition the subjects were asked to perform a 50% contraction followed by a 0.5 second rest and then a max isometric contraction. In the non-PAP phase, the subject was asked to perform a maximal isometric contraction. The subjects were randomized so that they would either start in the PAP condition or the non-PAP condition. There was a one minute rest given between each trial as well as between the conditions. Peak torque, rate of force development (RFD), impulse every one second, peak impulse, EMG frequency, and EMG amplitude were all measured. Dependent t tests were used to analyze differences between the two conditions and the level of significance was set at p < 0.05. Results: Peak torque was calculated for each condition; peak torque for non-PAP was 68.35 ± 18.04, PAP was 64.84 ± 16.03. Rate of force development non-PAP was 193.02 ± 131.01, PAP was 225.55 ± 114.36. Impulse every second non-PAP was 44.73 ± 11.71, PAP was 47.29 ± 17.38. Peak impulse non-PAP was 96.35 ± 48.90, PAP was 75.72 ± 39.57. EMG amplitude was 1292.62 ± 777.87, PAP was 1135.76 ± 708.92. EMG frequency non-PAP was 131.06 ± 18.38, PAP was 130.20 ± 18.82. Statistical analysis indicated that there was a significant difference (p = 0.008) between peak impulse in the non-PAP and PAP conditions. Conclusion: The significant difference that was seen between the impulses shows that there was more muscle activity when post activation potentiation was used with an isometric biceps contraction.


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