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INTRODUCTION: L-arginine is a non-essential amino acid that is precursor to synthesizing Nitric Oxide (NO). It is responsible for regulating blood pressure and improving exercise efficiency and tolerance, along with improvement in vasodilation. Thus it optimizes blood flow. Increased blood flow to active muscles increases substrate utilization to improve muscle recovery and protein synthesis during and after exercise. This allows for greater removal of metabolites lactate and ammonia that are related to muscle fatigue which inhibit exercise performance. Studies have shown that L-arginine supplementation has been a beneficial treatment for individuals that have hypertension, chronic heart failure, type 2 diabetes, and other types of cardiovascular diseases. PURPOSE: The purpose of this study was to evaluate the effects short term consumption of L-arginine had on the body’s blood lactate levels and individual’s performance. METHODS: 5 male students (age 24.8 ± 4.83 yrs) from the University of Texas at Arlington took part in this research study on the short term effects of L-arginine on blood lactate levels and performance during a 20 minute submaximal exercise test. Subjects came in for two trials, one per week to complete the study. Submaximal exercise test was done on an ergometer bike. Blood lactate levels were obtained and analyzed by the Accusport Lactate Analyzer. Baseline measurements of the heart rate, RPE, blood pressure, and blood lactate were taken prior, during and after the exercise. Following the completion of the 20 minute submaximal exercise test, the distance of the subject was recorded. The alpha level of significance was set at p ≤ 0.05. RESULTS: The average heart rate calculated from the submaximal test with the placebo was 116.28 ± 38.61 bpm while the heart rate with L-arginine was 119.75 ± 42.05 bpm. The distance with the placebo was 7.6 ± 0.23 and the rate of perceived exertion was 8.1 ± 2.6. With the supplement L-arginine the distance was 7.68 ± 0.22 km and the rate of perceived exertion was 7.2 ± 2.09. Blood lactate with the placebo was 6.5 ± 1.40 mmol/L while the L-arginine was 5.14 ± 1.39 mmol/L. The significance level was p = 0.17. CONCLUSION: The result of this study indicated that there was no significant difference (p = 0.17) on blood lactate acid between the placebo cornstarch and L-arginine during submaximal exercise. However, 3 out of 5 of the subjects blood lactate showed a small decrease and improvement the second time they did the submaximal test after taking the supplement L-arginine. More research should be done over a longer period of time to see if there is a significant change while taking the supplement L-arginine.


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