Effects Of Caffeine On Blood Lactate During Submaximal Exercise In Women
•INTRODUCTION: Blood Lactate ([La¯]b) is the buildup of the byproduct lactic acid (LA) in the blood. LA is present at rest, but is increased during exercise. The rate of clearance of LA is an indication of fitness levels. Research shows that a pre-exercise caffeine supplementation further increases the accumulation of blood lactate. •PURPOSE: The specific purpose of this research study was to ask the question does a pre-exercise caffeine supplement increase heart rate, blood pressure, distance traveled and post-exercise blood lactate levels during a submaximal exercise bout while decreasing the overall rate of perceived exertion in a moderately trained individual. •METHODS: Five women (W; age 23.2 ±2.168) of good physical condition, volunteered to participate in this study. Each subject had their body fat measured with a bioelectrical impedance analysis machine (BIA) and their resting values were obtained including height (cm), weight (kg), heart rate (HR) and blood pressure (BP). Resting blood lactate (mmol/L) was taken 30 minutes prior to exercise. Each subject was given either a NoDoz pill (200 mg of caffeine) or a Tylenol pill which contained zero caffeine. Each subject then performed a 30 minute submaximal aerobic bout on a cycle ergometer. During each test, heart rate, blood pressure, and rate of perceived exertion (RPE) were recorded every 10 minutes until the conclusion of exercise bout. As soon as exercise was terminated, a final blood lactate was acquired. •RESULTS: The percent body fat of the five women tested was 24.36 ±0.05%, height was 167.13 ±11.4 cm, and weight was 65.71 ±5.2 kg. The resting heart rate of the control group (P) was 84.8 ±5.0 bpm compared to 83.6 ±12.8 bpm in the experimental group (E) which was not significantly different (p > 0.05). Resting blood lactate was 1.7 ±0.5 mmol/L (P) compared to that of 1.24 ±0.5 mmol/L (E) which also was not a significant difference (p > 0.05). The maximal values: HR (146 ±14.6 bpm (P); 155.2 ±17.5 bpm (E)); RPE (14.2 ±1.8 (P); 13.8 ±1.6 (E)); and blood lactate (5.66 ±1.6 mmol/L (P); 6.36 ±1.3 mmol/L (E)) were not significantly different (p > 0.05). The overall total distance traveled was 12.4 ±0.9 km (P) and 12.7 ±0.8 km (E) which also was not significantly different (p > 0.05). •CONCLUSION: The results of this study indicate that a pre-exercise caffeine supplement did not improve performance during submaximal workloads while decreasing the overall RPE. Furthermore, the overall blood lactate production was higher after receiving the caffeine supplement compared to receiving a placebo. However, these results were not significant. The results may be attributed to each subject’s age and fitness levels.