Quinine Ingestion During the Latter Stages of a 3,000-m Time Trial Fails to Improve Cycling Performance

Abstract

The ingestion of quinine, a bitter tastant, improves short-term (30 s) cycling performance, but it is unclear whether this effect can be integrated into the last effort of a longer race. The purpose of this study was to determine whether midtrial quinine ingestion improves 3,000-m cycling time-trial (TT) performance. Following three familiarization TTs, 12 well-trained male cyclists (mean ± SD: mass = 76.6 ± 9.2kg, maximal aerobic power = 390 ± 50W, maximal oxygen uptake = 4.7 ± 0.6L/min) performed four experimental 3,000-m TTs on consecutive days. This double-blind, crossover design study had four randomized and counterbalanced conditions: (a)Quinine 1 (25-ml solution, 2mM of quinine); (b)Quinine 2, replicate of Quinine 1; (c)a 25-ml sweet-tasting no-carbohydrate solution (Placebo); and (d)25ml of water (Control) consumed at the 1,850-m point of the TT. The participants completed a series of perceptual scales at the start and completion of all TTs, and the power output was monitored continuously throughout all trials. The power output for the last 1,000m for all four conditions was similar: mean ± SD: Quinine 1 = 360 ± 63W, Quinine 2 = 367 ± 63W, Placebo = 364 ± 64W, and Control = 367 ± 58W. There were also no differences in the 3,000-m TT power output between conditions. The small perceptual differences between trials at specific 150-m splits were not explained by quinine intake. Ingesting 2mM of quinine during the last stage of a 3,000-m TT did not improve cycling performance.