Mouth rinsing with a bitter solution without ingestion does not improve sprint cycling performance

Recently, we have shown that combining mouth rinsing with the ingestion of a 2 mM quinine solution immediately before a 30-s cycling sprint significantly improves performance. However, the strong bitterness of such a solution produces an unpleasant taste and evokes nausea at higher concentrations. Given the possibility that mouth rinsing with quinine without ingesting it may not produce nausea, a mouth rinse only protocol may be a more practical approach to administer quinine for improving exercise performance. The purpose of the present study was to determine whether mouth rinsing with quinine without ingesting it improves 30-s sprint cycling performance.

Twelve competitive male cyclists performed a 30-s maximal cycling sprint immediately after rinsing their mouth for 10 s with either a 10 mM bitter quinine solution (QUI), plain water (WAT), a 7.1 % w/v sweet glucose solution (GLU), or no solution at all (control; CON). Sprint performance was assessed, and heart rate, ratings of perceived exertion and blood variables were measured pre- and post-exercise.

Mean power output during the 30-s sprint (QUI 888 ± 38; CON 873 ± 39; WAT 885 ± 37; GLU 873 ± 42 W; p = 0.431) as well as peak power (QUI 1230 ± 61; CON 1,208 ± 65; WAT 1,220 ± 70; GLU 1,202 ± 59 W; p = 0.690) were similar between the four conditions. There were no significant differences in any other performance measures, heart rate, subjective ratings or blood variables between conditions.

Mouth rinsing with a bitter tasting quinine solution without ingestion does not improve 30-s sprint cycling performance.