[Nick Voth is currently finishing his degree in Exercise Science from Bowling Green State University, where he competes on the Cross Country team. He is an Applied Sports Science Intern at Athletic Lab.]

Developing proper fueling strategies is always a goal for coaches and athletes across all sports. Particularly, the use of carbohydrates (CHO) before and during competition can optimize performance. CHO fueling typically consists of ingestion of a commercially available food, gel, or sports drink. Other fueling strategies have been investigated, and thus, the concept of CHO mouth rinsing has surfaced. CHO mouth rinsing involves rinsing a solution in the oral cavity for a short duration and subsequently spitting it out. The first of this two-part blog will discuss implications for CHO mouth rinsing for endurance sports athletes.

There are a couple potential benefits associated with CHO rinsing as opposed to ingestion. The first, and perhaps of most concern to athletes when developing a fueling strategy, is decreased gastrointestinal issues. Many athletes are hesitant to fuel just prior or during competition in fear of gastrointestinal issues that may hinder performance. Consequently, CHO rinsing may allow for an ergogenic enhancement while avoiding gastrointestinal distress. Secondly, albeit very minor, is the additional mass added to the athlete followed by ingestion of food or drink during competition. In sports where fatigue may be dependent upon an athlete’s ability to move one’s mass, the addition of unnecessary weight may result in earlier onset of fatigue. Therefore, CHO mouth rinsing may be the solution that many athletes have been seeking.

Endurance exercise can greatly benefit from CHO mouth rinsing. A systematic review completed by de Ataide e Silva et al. (2014) revealed that CHO mouth rinsing enhances cycling and running performance approximately one hour in duration at about 75% Wattmax or 65% VO2max. Rollo, Williams, and Nevill (2011) found similar results, however, their study focused on the effects of CHO rinsing compared to CHO ingestion. In this study, runners reported to the laboratory after an overnight fast and completed a one-hour run protocol in the following three conditions: ingestion of a CHO solution, ingestion of a placebo solution, or mouth rinse of a CHO solution. The solutions were delivered to the runners 30 minutes before, immediately before, and in 15-minute intervals during the run. The CHO ingestion and CHO mouth rinse conditions resulted in greater distances covered over one hour, however, it was found that the distance covered with CHO ingestion was significantly higher than the mouth rinse (Rollo, Williams, & Nevill, 2011). In contrast, Pottier et al. (2008) found CHO mouth rinsing to be more effective than ingestion in cycling exercise about one hour in duration.

The mechanisms by which CHO mouth rinsing enhances short duration endurance exercise (one hour) can explain the opposing results observed by Rollo, Williams, and Nevill (2011) and Pottier et al. (2010). CHO mouth rinsing is thought to enhance performance via central nervous system excitement. As an athlete rinses with a CHO solution, oral receptors are stimulated causing excitement to pleasure and reward centers in the brain (Stellingwerff & Cox, 2014). Therefore, it appears that the performance benefits from CHO mouth rinsing in shorter duration endurance activities are not related to metabolism or substrate oxidation. For events lasting longer (approximately two hours), CHO ingestion seems to provide the greatest performance enhancement because glycogen stores are severely suppressed and may eventually become completely depleted (Stellingwerff & Cox, 2014). Keeping this idea in mind, the reason for the differences observed between CHO mouth rinse and ingestion can possibly be attributed to the relative state of energy availability in the athlete prior to completing each test. Rollo, Williams, and Nevill (2011) tested runners in a fasted state, while Pottier et al. (2010) encouraged subjects to eat a meal high in CHO content at least three hours before the test. It is likely that the runners only received a benefit from CHO ingestion because they were exercising in a fasted state. Had they come to the laboratory completely fueled, the researchers may not have discovered a significant difference between CHO mouth rinsing and CHO ingestion. In most cases, athletes will not compete in a fasted state, so the performance benefits from CHO mouth rinsing may still be achieved. Relative energy availability seems to play a role in the effectiveness of CHO mouth rinsing, but may still be a viable option for athletes considering alternative fueling strategies.

Outside of long duration endurance activities, CHO mouth rinsing seems to be a sufficient fueling strategy immediately prior to and during competition. Athletes prone to gastrointestinal distress should consider this fueling strategy in training and competition. Part Two of this blog will shift attention to speed-power athletes and how CHO mouth rinsing can be used across all sports.

References

de Ataide e Silva, T., Di Cavalcanti Alves de Souza, M.E., de Amorim, J.F, Stathis, C.G., Leandro, C.G., & Lima-Silva, A.E. (2014). Can carbohydrate mouth rinse improve performance during exercise? A systematic review. Nutrients, 6(1), 1-10. doi: 10.3390/nu6010001

Pottier, A., Bouckaert, J., Gilis, W., Roels, T., & Derave, W. (2010). Mouth rinse but not ingestion of a carbohydrate solution improves 1-h cycle time trial performance. Scandinavian Journal of Medicine and Science in Sports, 20, 105-111. doi: 10.1111/j.1600-0838.2008.00868.x

Rollo, I., Williams, C., & Nevill, M. (2011). Influence of ingesting versus mouth rinsing a carbohydrate solution during a 1-h run. Medicine & Science in Sports & Exercise, 43(3), 468-475. doi: 10.1249/MSS.0b013e3181f1cda3

Stellingwerff, T., & Cox, G.R. (2014). Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Applied Physiology, Nutrition & Metabolism, 39(9), 998-1011. https://doi.org/10.1139/apnm-2014-0027