INTRODUCTION: Blood lactate concentration reflects the balance between lactate production and clearance. It is considered a marker of exercise intensity and muscle glycolysis. It is expressed in mmol/L of lactate found in the plasma of blood. Research shows that caffeine, a stimulant with ergogenic properties, increases blood lactate levels. It is also shown to improve aerobic performance and increase time to exhaustion during exercise. The physiological underpinnings of caffeine-provoked endurance performance gains are not yet fully understood but may be related to enhanced calcium availability, adenosine receptor antagonism and consequential reductions in pain and perceived exertion, and augmented lipolysis and subsequent glycogen sparing, among other hypothesized mechanisms. PURPOSE: The purpose of this study was to look at the effects of caffeine gum on blood lactate levels during submaximal exercise. METHODS: Six men (age 23.3 ± 1.97 yrs) of the UTA Kinesiology department, volunteered to participate in this study. Each subject filled out a caffeine questionnaire prior to testing. Each subject was given either two pieces of caffeine gum or sugar-free mint gum prior to testing. Each subject then performed a 30 minute submaximal exercise test to 70% age-predicted max heart rate on a cycle ergometer. Prior to gum consumption and again before starting the test, heart rate (HR), blood pressure (BP), and rate of perceived exertion (RPE) were recorded, along with blood lactate levels measured by the Accutrend Lactate Analyzer. During each test heart rate, blood pressure, rate of perceived exertion, and blood lactate levels were recorded every 10 minutes. RESULTS: The blood lactate levels measured during rest after chewing caffeine gum was 3.40 ± 1.34 mmol/L, which approached a significant difference (p=0.036, p<0.05) from blood lactate levels after chewing mint gum (2.08 ± 0.61 mmol/L). Average values: La1 (C: 2.15 ± 0.67 mmol/L; M: 1.87 ± 0.37 mmol/L); La10 (C:5.95 ± 1.45 mmol/L; M: 9.33 ± 5.91 mmol/L); La20 (C:5.67 ± 2.06 mmol/L; M: 6.83 ± 2.85 mmol/L); La30 (C:5.42 ± 0.87 mmol/L; M:5.75 ± 1.87 mmol/L); and La5 (C:4.40 ± 1.82 mmol/L; M: 4.38 ± 1.77 mmol/L) were not significantly different between gum types (p>0.05). However there was a significant difference (p<0.05) between gum types for systolic blood pressure at 10 (BP10) (C:127.5 ± 9.35 mmHg; M: 149.17 ± 9.17 mmHg) and 20 (BP20)(C:135.83 ± 11.14 mmHg; M: 155.83 ± 9.17 mmHg) minutes of cycling. CONCLUSION: The results of this study examined the effects of caffeine gum on blood lactate levels, heart rate, blood pressure, and rate of perceived exertion during submaximal cycling. However, the data indicates that caffeine gum does not have a significant effect on submaximal exercise.

• Exercise Protocol:• Resting measurements (La1,

HR1, and BP1)• Chew caffeine gum (C) or “non-

caffeine” mint gum (M)• Rest for 15 minutes followed

by La2, HR2, and BP2 measurements

• Completion of 30-minute submaximal cycling to 70% estimated Hrmax, obtaining measurements every 10 mins (La10, La20, La30, HR10, HR20, HR30, BP10, BP20, BP30, RPE10, RPE20, RPE30)

• 5 minutes of recovery followed by measurements La5, HR5, and BP5

ResultsAbstract

Introduction

Methods, cont’d

Purpose

Conclusions

Author: Sara Cleveland, Faculty Advisor: Judy Wilson, Ph.D.Cardiovascular Research Laboratory, The University of Texas at Arlington Arlington, TX; KINE 4400, 12/4/13

THE EFFECTS OF CAFFEINE ON BLOOD LACTATE THE EFFECTS OF CAFFEINE ON BLOOD LACTATE LEVELS DURING SUBMAXIMAL EXERCISE LEVELS DURING SUBMAXIMAL EXERCISE

The purpose of this study was to evaluate the effects of caffeine gum on blood lactate levels during submaximal exercise.

• This study examined the effects of caffeine gum on blood lactate levels, heart rate, blood pressure, and rate of perceived exertion during submaximal cycling. However, the data indicated that caffeine gum does not have a significant effect on submaximal exercise.

• Suggestions for future studies: larger sample size, chronic supplementation, control group, incremental exercise test.

• Six moderately active male students from the University of Texas at Arlington Kinesiology Department volunteered for this study.

Dependent t-tests showed no significant difference in La1, La10, La 20, La30, La5, measurements (p>0.05). It did however, show a significant difference in La2 measurements (p=0.036).

Dependent t-tests showed a significant difference in systolic blood pressure at 10 and 20 minutes of exercise between the two gum types (p<0.05). No significant difference in diastolic blood pressure was found (p>0.05).

• Instruments used for this study were the Monark Exercise AB 818E Ergomedic Exercise Bike, Polar FT1 Fitness Heart Rate Monitor, ADC 752M Diagnostix Mobile Aneroid Sphygomomanometer and stethoscope, Accutrent Blood Lactate Analyzer blood lancet, Hirschmann Laborgerate Applicator and capillary tube, latex medical gloves, alcohol swabs, Borg scale for RPE.

• Subjects completed two days of testing separated by one weeks time• Blood lactate concentration reflects the balance between lactate

production and clearance. It is considered a marker of exercise intensity and muscle glycolysis.

• Previous research shows that caffeine, a stimulant with ergogenic properties, increases blood lactate levels.

• Caffeine is considered the most widely consumed drug worldwide.• The most customary type of caffeine consumption has been coffee.• Caffeine is quickly metabolized in the liver and is converted into

three types of dimethylxanthine that can be held in blood for a long time and produce its related signals.

• The physiological underpinnings of caffeine-provoked endurance performance gains are not yet understood definitively.

Methods