Purpose: There is evidence that carbohydrate (CHO) mouth rinsing can improve endurance exercise performance as well as muscle force production and sprint performance. Whether the oral administration of non-CHO tastants also affects exercise performance is not known. The purpose of this study was to investigate whether mouth rinsing and ingesting a bitter-tasting solution of quinine improves maximal sprint cycling performance.
Methods: Fourteen competitive male cyclists performed a 30-s maximal cycling sprint immediately after rinsing their mouth for 10 s and then ingesting a 2-mM bitter quinine solution, plain water, a 0.05% (w/v) sweet aspartame solution, or no solution at all (control). Cycling power output was recorded during the sprint. Heart rate, perceived exertion, blood lactate, and blood glucose were measured preexercise, immediately postexercise, and 7 min postexercise.
Results: Quinine significantly improved mean power output by 2.4%-3.9% compared with the three other conditions [P ≤ 0.021, effect size (ES) = 0.81-0.85]. Peak power output in the quinine condition was higher compared with the water (3.7%, P = 0.013, ES = 0.71) and control (3.5% P = 0.021, ES = 0.84) conditions but was not significantly different from aspartame (1.9%, P = 0.114, ES = 0.47). There were no significant differences in cycling performance between water, aspartame, and control conditions. There were no differences in heart rate, perceived exertion, or blood variables between any of the conditions.
Conclusion: This study shows for the first time that mouth rinsing and ingesting a bitter-tasting solution immediately before a maximal sprint exercise can improve performance.