Introduction: Increasing skeletal muscle contraction ability via increasing its neural stimulations, is one of the methods can be effective in sport performance improvement. The aim of the present study was to evaluate the effect of supramaximal isometric conditioning contractions on muscle neural excitation and performance indices during bench press exercise.
Methods: Current research is a semi experimental study performed on 8 athlete men. Age range of them was 19 – 23. Doing resistance trainings was a part of their exercise program at least 2 months before study onset. Bench press with Barbell was used in the protocol of these study. Electromyography was used in order to assay the neural excitation of main muscles which are activated during bench press. In addition, 1-RM test was done so as to assess the performance of these muscles. The protocol of this study was approved by the ethics committee of Arak University of Medical Sciences (Code: IR.ARAKMU.REC.1400.357). All subjects participated in this study voluntarily and they had no illness or injury at the start of the research.
Results: Neural excitation and performance of the muscles increased significantly during strength bench press, following conditioning contractions. This research was reviewed in Islamic Azad University - Arak Unit and approved with the ethics code IR.IAU.ARAK.REC.1401.096. Informed consent was obtained from the participants and they were assured that their information would be confidential
Conclusions: Doing supramaximal isometric conditioning contractions prior to doing strength bench press with barbell, increased neural excitation and performance indices of main muscles activated in this exercise. 

Introduction: Athletes use diverse strategies, including caffeine supplementation, to reduce fatigue and improve their performance. The aim of the present study was to evaluate the effect of the post-activation potentiation method and caffeine supplementation on peripheral fatigue after Wikstrom's fatigue protocol in young male volleyball players.
Methods: In this study, forty male volleyball players with an average age of 27.33 ± 1.78 years and an average weight of 76.5 ± 7.45 kg participated. They were divided into four experimental groups: a group that used only the PAP method (n=10), a group that consumed only caffeine (n=10), a group that both performed PAP and consumed caffeine (n=10), and a control group (n=10). For the groups receiving caffeine, a caffeine supplement was administered at a dose of 6 mg per kilogram of body weight, 15 minutes before starting the protocol. PAP exercises were performed at an intensity of 70% of the one-repetition maximum. Blood samples were taken one hour before and one hour after completing the Wikstrom six-station protocol. All subjects participated in this study voluntarily and they had no illness or injury at the start of the research.
Results: The results of the present study showed that the implementation of PAP along with caffeine showed a significant increase in the variables of time to exhaustion and the number of rounds (p<0.05), while the rate of ammonia showed a significant decrease (p<0.05). In contrast, uric acid showed no significant difference (p>0.05).
Conclusions: The results of the present study, showed that the use of caffeine reduces peripheral fatigue. Also, since the use of PAP did not have an adverse effect on the participant's performance, athletes can use this method concurrently with caffeine to improve their performance in endurance activities.