The Physiological Responses of Caffeine Supplementation During Repeated-Sprint Activity

Abstract

Caffeine is one of the most widely used drugs in the world due to its benefits of increasing mental and physical capabilities. Caffeine also is commonly used as an ergogenic aid when performing repeated-sprint activity (RSA). PURPOSE: The purpose of this study is to examine the effects of 200 mg of caffeine during RSA on heart rate (HR), rating of perceived exertion (RPE), blood lactate concentration (BLa), and sprint time (ST). METHODS: Thirty-two students (Age: 22.19 ± 2.29 years) participated in the study. The study followed a randomized crossover design, in which each participant ingested either 200 mg of caffeine or placebo 45 minutes prior to sprinting. The sprinting protocol consisted of three sets of six maximal-effort 30-meter sprints. Each sprint covered a 15-meter distance between the starting and the secondary marker, such that each subject sprinted down to the secondary and back to the starting. Each of the sprints in a set were separated by a total of 20 seconds of active recovery. Following each set, HR, BLa, ST, and RPE were recorded. RESULTS: The caffeine trials were not significantly different than the placebo for HR and RPE. However, for RPE, there was a main effect for time [F(3,93) = 292.810, p < 0.001]. The caffeine trials (Resting: 1.30 ± 0.52 mmol/L; Set 1: 11:33 ± 2.38 mmol/L; Set 2: 13.26 ± 3.02 mmol/L; Set 3: 13.67 ± 2.49 mmol/L) elicited increased BLa compared to the placebo (Resting: 1.37 ± 0.53 mmol/L; Set 1: 9.24 ± 2.43 mmol/L; Set 2: 11.46 ± 2.87 mmol/L; Set 3: 11.83 ± 2.55 mmol/L). The caffeine trials (Set 1: 6.78 ± 0.58 secs; Set 2: 6.81 ± 0.55 secs; Set 3: 6.85 ± 0.57 secs) also produced a decreased average ST compared to the placebo (Set 1: 7.00 ± 0.64 secs; Set 2: 7.02 ± 0.62 secs; Set 3: 7.12 ± 0.63 secs). For the average ST, there were significant main effects for condition [F(1,31) = 36.839, p < 0.001] and time [F(2,62) = 5.806, p = 0.006]. CONCLUSION: Caffeine supplementation of 200 mg elicits an increase in RSA in college-aged non-athletes.