Mouth Rinsing and Ingesting Unpleasant Salty or Bitter Solutions After Heavy-Intensity Cycling Does Not Influence Sprint Performance or Knee-Extensor Force in Trained Cyclists Edward A. Gray, 1,2,3 Rocco Cavaleri, 1,2 and Jason C. Siegler 1,4 1 School of Health Sciences, Western Sydney University, Campbelltown, NSW, Australia; 2 Brain Stimulation and Rehabilitation (BrainStAR) Lab, School of Health Sciences, Western Sydney University, Campbelltown, NSW, Australia; 3 Division of Public Health, Sport and Wellbeing, University of Chester, Chester, United Kingdom; 4 College of Health Solutions, Arizona State University, Phoenix, AZ, USA Purpose: The present study investigated the effect of unpleasant salty or bitter tastes on cycling sprint performance and knee- extensor force characteristics in different fatigue states. Methods: Following a familiarization session, 11 trained male cyclists completed 3 experimental trials (salty, bitter, and water) in a randomized crossover order. In each trial, participants cycled at 85% of the respiratory compensation point for 45 minutes and then, after a 5-minute rest, completed a 1-minute sprint. Muscle-force characteristics were assessed using 2 knee-extensor maximal voluntary contractions immediately before, between, and after the cycling efforts. Participants mouth-rinsed and ingested 25 mL of test solution (salty, bitter, and water) immediately before each maximal voluntary contractions and the 1-minute sprint. Results: There were no significant differences in mean and peak power output during the 1-minute sprint between conditions (mean power: 528 [71] W, 524 [70] W, and 521 [80] W in the water, salt, and bitter conditions, respectively). Muscle-force production was impaired in all conditions after the heavy-intensity cycling, evidenced by a decline in maximum force production (P = .01, effect size = 0.32) and 100- to 200-millisecond impulse (P = .04, effect size = 0.27). However, there were no significant differences between conditions in maximal force or impulse measures at rest or after exercise. Conclusion: These data question whether unpleasant tastes can influence muscle-force production and do not support that they may be used as an ergogenic aid for a cycling sprint performed under fatigued conditions. Keywords: quinine, unpleasant taste, tastant, fatigue It is well established that appropriate nutrition is crucial to athletic performance. 1 In general, substances must first be ingested and metabolized for their benefit to be realized. However, research over the past 2 decades has revealed that experiencing certain tastes or nutrients, without ingestion, can benefit exercise performance. 2 This was first discovered when it was shown that rinsing the mouth with carbohydrate and then expectorating improved 1-hour cycling time-trial performance by 2.9%. 3 The ergogenic effect of carbohy- drate mouth rinsing raises the possibility that experiencing other tastes could also influence exercise performance. Tasting quinine, a strong bitter compound, has been shown to improve 30-second cycling sprint performance by 3.9%. 4 Notably, unlike carbohydrate mouth rinsing, the quinine solution must be ingested in order to be beneficial 5 because many of the bitter specific taste receptors are located at the back of the tongue and the throat. 6 However, the effects of tasting quinine on exercise perfor- mance remain equivocal because more recently it has been shown that mouth rinsing and ingesting quinine at the start 7 or during the latter stages 8 of a 3-km time trial did not improve overall exercise performance. Furthermore, recently, we found quinine ingestion to have no influence on cycling sprint performance. 9 The mechanisms via which quinine may exert an ergogenic effect are purported to be related to increasing autonomic nervous system activation 4,10 and/or increasing corticomotor excitability. 11 The autonomic nervous system response to tasting quinine may be driven by its unpleasantness, 10 and consequently, it is plausible that other unpleasant tastes may also have an influence on exercise. Therefore, in a recent study, we directly compared 2 unpleasant solutions, salty and bitter, and explored some of the purported mechanisms via which tasting quinine may exert an ergogenic effect. 12 However, contrary to our hypothesis, we found that neither of the unpleasant tastes influenced quadricep neuromuscu- lar function or corticomotor excitability. 12 Fatigue is defined as an exercise induced decrease in the ability to maintain a given work output. The null effect of the unpleasant tastes on neuromuscular function in our recent work could be attributable to the measures being taken at rest in the absence of fatigue. 12 Although ingesting quinine has been shown to be ergo- genic during a 30-second sprint, 4 which begins in a nonfatigued state, the all-out style sprint does induce significant neuromuscular fatigue. Indeed, Fernandez-del-Olmo et al 13 found that, after a 30-second all-out cycling sprint, quadricep maximal voluntary force during an maximal voluntary contractions (MVC) declined by ∼16%. Thus, it is plausible that the ergogenic potential of quinine, 4 or other unpleasant tastes, may be augmented in the presence of fatigue. Supporting this, despite an unpleasant salt solution having no influence on neuromuscular function at rest, 12 recently Khong et al 14 found that mouth rinsing a salt solution attenuated neuromus- cular fatigue after 30 minutes of cycling exercise. However, the influence of a bitter taste on neuromuscular fatigue is unknown. Furthermore, the effect of salty or bitter tastes on exercise perfor- mance in a fatigued state has not been previously explored. Due to the equivocal outcomes in research investigating the influence of unpleasant tastes on exercise performance, the Cavaleri https://orcid.org/0000-0001-9499-1703 Siegler https://orcid.org/0000-0003-1346-4982 Gray (edwardandrew@live.co.uk) is corresponding author, https://orcid.org/0000- 0003-2274-2147 232 International Journal of Sports Physiology and Performance, 2025, 20, 232-237 https://doi.org/10.1123/ijspp.2023-0314 © 2025 Human Kinetics, Inc. ORIGINAL INVESTIGATION Brought to you by Human Kinetics, Inc. | Authenticated CrystalR@hkusa.com | Downloaded 02/10/25 08:55 PM UTC