The effect of moderate dose of caffeine supplementation on endurance and muscle strength of male bodybuilders

Introduction: The purpose of this research is to investigate the effect of moderate dose of caffeine consumption in one session on endurance performance and strength of male athletes.
Methods: The research method is semi-experimental. The statistical population of this research consisted of all active male students of Azad University in 2017. Statistical sample of 60 male athletes (age: 19.63.39±39 years; weight: 68.90±7.63 kg; height: 175.45±5.81 cm; fat percentage: 8.01±2.42 percent) They were randomly selected and divided into two groups of 30 endurance or strength based on their sports field. Subjects performed pre-test and post-test separately. In the first attempt of the subjects, the test of running to exhaustion with 80% of the reserve heart rate (endurance group), one repetition maximum (IRM) and also muscular endurance (number of repetitions until fatigue with 60% of 1RM) for two movements of chest press and leg press ( Power group) performed. After a week of rest, the subjects returned to the laboratory for the second stage of the test and were divided into two groups of caffeine or placebo in terms of Vo2max (endurance group and maximum strength). In a single-blind design, one hour after taking capsules containing 6 mg of caffeine or placebo (starch) per kilogram of body weight, the duration of running to stop, muscle strength and endurance of the subjects were recorded for two movements of chest press and leg press. . The results of the statistical analysis of the data were performed with the independent and dependent t-test at a significant level (P≥0.05).
Results:  In the caffeine group, the running time and also the number of repetitions with 60% of IRM for the chest press and leg press showed a significant increase compared to the pre-test phase (P≥0.05), while no significant changes were observed in the placebo group (05 /0≤P). The changes in the duration of running, the number of repetitions of chest press and leg press of the subjects in the caffeine group compared to the placebo group were statistically significant (P≥0.05), but no significant change was observed for their muscle strength (P≤0.05)..
Conclusion: According to the results of the research, it can be said that a moderate dose of caffeine can have positive effects on endurance performance, especially at maximum intensities, and also on some strength parameters at moderate intensities.