K.F. Sander, S.A. Sander, T.E. Cherry, V.A. Wimer, A.K. Higgins, S.W. LaVigne, J.M. McKenzie

Gonzaga University, Spokane, WA

PURPOSE: Caffeine is thought to have ergogenic qualities due to its pain suppressing qualities as an adenosine receptor antagonist. The purpose of this study was to determine if caffeine ingestion would increase time to failure (TF) of an anaerobic exercise. METHODS: 11 untrained college-aged males that ingested less than 200 mg of caffeine per week were recruited via email. Each subject visited the lab 3 times. During the first visit informed consent was collected and the subject’s height and weight was measured. Subjects were familiarized with the procedures and given the chance to ask any questions about the study. In visits 2 and 3, implementing a counter-balanced, single-blind protocol the participants consumed either a placebo or a caffeine pill (6 mg caffeine/kg body weight). The participants received the opposite treatment the following visit, which was a minimum of 72 hours later. One hour after ingestion of the pill participants performed a wall sit until failure. Heart rate (HR), blood lactate concentration ([La-]), and rate of perceived exertion (RPE) were measured immediately before exercise. HR and RPE were again measured at ten-second increments during exercise until failure. Also, [La-] was again measured 2 minutes post failure. RPE slope was calculated by looking at the rate of increase in RPE v. time. HR slope was calculated by looking at the rate of increase in HR v. time. RESULTS: TF (p = 0.881), RPE slope (p = 0.406), and Δ [La-] (p = 0.259) were all non-significant between trials. For the caffeine trial, mean ± SD for TF was 132.5 ± 35.7 seconds, for RPE slope was 1.30 ± 0.41, and for Δ [La-] was 3.94 ± 3.54 mmol/L. For the placebo trial, mean ± SD for TF was 133.8 ± 44.9 seconds, for RPE slope was 1.35 ± 0.46, and for Δ [La-] was 2.08 ± 4.25 mmol/L. There was a significant, negative correlation between TF and RPE slope for the caffeine trial (r = -0.735, p = 0.010) and the placebo trial (r = -0.693, p = 0.018). CONCLUSIONS: TF, RPE slope, and Δ [La-] were all non-significant between trials, suggesting that caffeine did not have an ergogenic effect on the duration of a wall sit. RPE slope and HR slope were not significantly correlated, suggesting that the participants did not fully understand the Borg scale or their pain originated from a psychological source, rather than physiological. RPE slope and TF had a significant negative correlation for both conditions, meaning the steeper the RPE slope, the shorter the TF.

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