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THE EFFECTS OF CAFFEINE CONSUMPTION ON THE BLOOD LACTATE LEVELS IN RECREATIONALLY ACTIVE COLLEGE-AGED MALES James S. Hoerig: Cardiovascular Research Laboratory, The University of Texas at Arlington, Arlington, TX; KINE 4400 Abstract Results (continued) Methods Table 1. Mean results from placebo and supplement trials. . THE EFFECTS OF CAFFEINE CONSUMPTION ON THE BLOOD LACTATE LEVELS IN RECREATIONALLY ACTIVE COLLEGE-AGED MALES Author: James Stephen Hoerig Faculty Sponsor: J.R. Wilson, PhD. INTRODUCTION: Caffeine has become the most widely used drug in the world. This xanthene derivative causes an increase in catecholamines circulating throughout the blood, and is commonly used by athletes looking for an increase in athletic performance. Besides having a stimulating effect on the cardiovascular and nervous system, many report a decrease in their levels of perceived exertion while performing exercise in conjunction with the drug. Blood lactate is a common way to quantify objectively the levels of exertion an athlete may be experiencing during exercise, as it is shown to increase linearly with perceived exertion and muscular fatigue. Additionally, because of the sympathetic mimicking properties of caffeine and other xanthene derivatives, oxygen saturation in circulating blood could be affected and contribute to perceived fatigue. Age 80.2 ± 16.9 kg Instruments used for this study were Polar Heart Rate monitor, blood lactate analyzer, Borg scale for perceived exertion, standard blood pressure cuff, Acc U Rate CMS 50 pulse oximeter. Subjects completed two trials on separate days separated by at least 48 hours, but no more than 7 days. Exercise Protocol: Ingestion of 200mg caffeine or placebo tablets (acetaminophen). Collection of demographic data with a short rest period following. Collection of resting BLA, HR, Systolic BP, and O₂ Saturation. Subject participates in a short dynamic warm up routine. Subject begins run and run time is recorded along with RPE every 4 laps. Immediately upon completing the run an Exercising HR, SBP, O₂ Saturation and BLA are measured. Subjected is escorted back to the metabolic lab and undergoes a 5 minute recovery period. Recovery BLA, HR, SBP and O₂ Saturation are measured. RESULTS: There was a significant difference in the run time’s pre and post supplementation with caffeine (p=0.005). There was, on average, a 6.14% difference in run times following supplementation. There was no significant difference in resting heart rate, however exercising heart rate and recovery heart rate showed significant increases (p=0.0128 and p=0.0005, respectively). Furthermore, there was no significant difference in resting or recovery blood pressure, but exercising blood pressure was increased in those who supplemented with caffeine (p=0.015). Oxygen saturation at rest and during exercise showed no significant differences, however during recovery there was a significant decrease in oxygen saturation levels (p=0.005). There were no significant differences in blood lactate levels during any part of the protocol. RPE during the beginning, intermediate, and end run phases all showed significant decreased (p=0.006, p=0.001 and p=0.003, respectively). CONCLUSION: Caffeine is useful in decreasing the levels of perceived exertion an athlete may experience during exertion, however no significant changes in blood lactate levels are shown during any phase of exercise (rest, exercise and recovery). The use of caffeine also shows increases in physiological variables such as heart rate, systolic blood pressure, and most of which are seen more prominently during exercise and recovery. Levels of oxygen saturation show little change during the use of caffeine during exercise which suggests an alternative means for the increased performance (shown as a decrease in run times) show by individuals during submaximal exercise. Purpose The purpose of this study was to analyze the effects of caffeine supplementation on the rating of perceived exertion, blood lactate accumulation, oxygen saturation, heart rate and blood pressure during sub-maximal exercise in recreationally athletic male students. Caffeine is the most widely used drug in the world. Xanethene derivative increases circulating cathecholamines in the blood. Caffeine is thought to increase stimulation of the sympathetic nervous system Caffeine is shown to alter levels of perceived exertion in athletes performing shuttle runs (Rouhola et al. 2010). Caffeine is not shown to decrease blood lactate levels in those performing anaerobic exercise (Rouhola et al. 2010). Weight METHODS: Six men, (age 23.5 ± 3.1 yrs, height 177.2 ± 6.4 cm, weight 80.2 ± 16.9 kg, BMI 25.4 ± 4.4) were asked to run a self-paced 1.5 mile run after obtaining informed consent. Prior to the run, demographic data was obtained and either a placebo (acetaminophen) or a 200mg caffeine tablet were given to the subject and a timer was started to allow adequate time for absorption. Resting levels of blood lactate, oxygen saturation, heart rate and blood pressure were taken. After 30 minutes the subject was escorted to the track where they were guided through a series of dynamic warm up exercises. The subject then began the 1.5 mile run. Every 4 laps the subject was asked for a rating of perceived exertion (a start, intermediate and ending perceived exertion). Upon completion of the run, a final run time was noted as well as heart rate, blood pressure, and oxygen saturation. The subject was then immediately escorted to the lab where a blood lactate was measured. After 5 minutes of recovery, the subject was evaluated for a recovery blood lactate level, oxygen saturation, blood pressure and heart rate. Height 23.5 ± 3.1 years 177.2 ± 6.4 cm PURPOSE: The purpose of this study was to analyze the effects of caffeine supplementation on the rating of perceived exertion, blood lactate accumulation, oxygen saturation, heart rate and blood pressure during submaximal exercise in recreationally athletic male students. Introduction Six recreationally athletic males volunteered to participate in this study. Results 16 180 14 Acetaminophen 160 12 Caffeine 140 Acetaminophen Caffeine 120 10 Acetaminophen Caffeine Run Time (s) 727.8 ± 115.9 683.1 ± 99.7 Rest HR (bpm) 64.5 ± 7.3 65.5 ± 4.9 Ex. HR (bpm) 159.3 ± 4.9 168.3 ± 5.7 Rec. HR (bpm) 106 ± 6.8 111.2 ± 6.6 Rest BLA (mmol/L) 1.52 ± 0.4 1.57 ± 0.3 Ex. BLA (mmol/L) 6.20 ± 2.1 6.95 ± 2.5 Rec. (mmol/L) 5.13 ± 1.3 5.61 ± 2.1 Rest O₂ Sat (%) 97.3 ± 1.1 97.1 ± 1.8 Ex. O₂ Sat (%) 95.8 ± 0.69 94.7 ± 0.69 Rec. O₂ Sat (%) 97.2 ± 0.90 96.2 ± 0.69 Rest. Sys. BP (mmHg) 121 ± 3 120 ± 2 Ex. Sys. BP (mmHg) 142 ± 8 147 ± 7 Start RPE 9.8 ± 1.2 9.8 ± 0.68 Inter. RPE 13 ± 2.1 11.8 ± 2.1 End RPE 14.5 ± 2.0 13.8 ± 1.9 Dependent t-tests showed significant differences (p<0.05) between placebo and supplementation trials in the categories of overall run time, rating of perceived exertion throughout all parts of the run, recovery O₂ saturation, exercising heart rate and blood pressure, along with recovery heart rate. Conclusion 100 8 80 6 60 4 40 2 20 0 0 RPE Start Run RPE Inter. RPE End Run Rest BLA Run Ex. BLA Rec. BLA Rest HR (bpm) Ex. HR (bpm) Rec. HR (bpm) Ex. SBP (mmHg) Rest O₂ Ex. O₂ Sat. Rec. O₂ Sat. (%) (%) Sat. (%) Caffeine may be useful in decreasing the levels of perceived exertion an athlete may experience during exercise, however no significant changes in blood lactate levels are shown during any phase of exercise (rest, exercise and recovery). The use of caffeine also shows increases in physiological variables such as heart rate and systolic blood pressure. Most of which are seen more prominently during exercise and recovery. Levels of oxygen saturation show little change during the use of caffeine.