Time course of tolerance to the performance benefits of caffeine

Abstract

The ergogenic effect of acute caffeine ingestion has been widely investigated; however, scientific information regarding tolerance to the performance benefits of caffeine, when ingested on a day-to-day basis, is scarce. The aim of this investigation was to determine the time course of tolerance to the ergogenic effects of a moderate dose of caffeine. Eleven healthy active participants took part in a cross-over, double-blind, placebo-controlled experiment. In one treatment, they ingested 3 mg/kg/day of caffeine for 20 consecutive days while in another they ingested a placebo for 20 days. Each substance was administered daily in an opaque unidentifiable capsule, and the experimental trials started 45 min after capsule ingestion. Two days before, and three times per week during each 20-day treatment, aerobic peak power was measured with an incremental test to volitional fatigue (25 W/min) and aerobic peak power was measured with an adapted version of the Wingate test (15 s). In comparison to the placebo, the ingestion of caffeine increased peak cycling power in the incremental exercise test by ~4.0 ±1.3% for the first 15 days (P<0.05) but then this ergogenic effect lessened. Caffeine also increased peak cycling power during the Wingate test on days 1, 4, 15, and 18 of ingestion by ~4.9 ±0.9% (P<0.05). In both tests, the magnitude of the ergogenic effect of caffeine vs. placebo was higher on the first day of ingestion and then progressively decreased. These results show a continued ergogenic effect with the daily ingestion of caffeine for 15–18 days; however, the changes in the magnitude of this effect suggest progressive tolerance.

Acute caffeine intake increases performance in the 15‐s Wingate test during the menstrual cycle

“…This researcher also verified that participants remained seated during the whole test. During the Wingate test, cycling power was obtained with a frequency of 1 Hz and the peak and mean cycling power (in W/kg) obtained during the test were recorded as previously described . In addition, peak and minimum cycling power were used to calculate the Wingate fatigue index (%) as previously suggested .…”

“…During the Wingate test, cycling power was obtained with a frequency of 1 Hz and the peak and mean cycling power (in W/kg) obtained during the test were recorded as previously described. 9 In addition, peak and minimum cycling power were used to calculate the Wingate fatigue index (%) as previously suggested. 4 23 The criteria to interpret the magnitude of effect size were: ≤0.2 trivial, >0.2-0.6 small, >0.6-1.2 moderate, >1.2-2.0 large, >2.0 very large.…”

“…However, evidence also suggests that doses <3 mg of caffeine/kg of body mass or the use of coffee as the form caffeine administration might be less effective than the use of 3–9 mg/kg via pure anhydrous caffeine or caffeinated energy drinks . Caffeine ergogenicity for the Wingate test might persist with daily ingestion of 3 mg/kg of caffeine for 15–18 days; however, the magnitude of its ergogenic effect is higher the first day of ingestion, suggesting tolerance to this substance . Lastly, caffeine might be used to improve both upper and lower body Wingate performance, which suggests that the effect of caffeine to enhance anaerobic performance is independent of the muscle mass involved in the exercise.…”

“…The above‐mentioned investigations have been carried out using samples of only male participants or women represented a low proportion of the study subjects, impeding a subanalysis of caffeine effects on female participants . The meta‐analysis of the caffeine ergogenic effect on Wingate performance carried out by Grgic 5 included 16 studies with 246 male participants and only 47 female participants.…”

“…The above-mentioned investigations have been carried out using samples of only male participants 2,4,8 or women represented a low proportion of the study subjects, impeding a subanalysis of caffeine effects on female participants. 1,3,9 The meta-analysis of the caffeine ergogenic effect on Wingate performance carried out by Grgic 5 included 16 studies with 246 male participants and only 47 female participants. Interestingly, the only investigation of caffeine effects on Wingate performance using a sample of female participants concluded that 5 mg/kg of caffeine was not effective to increase any performance variable measured during the Wingate test.…”