- A meta-analysis of 16 studies found that rinsing the mouth with a carbohydrate solution during endurance exercise has a small but statistically significant effect of improving performance compared to a placebo. - The overall effect size was 0.28, indicating a small performance benefit from carbohydrate mouth rinsing. Higher carbohydrate concentrations in the mouth rinse resulted in better performance. - Study characteristics like exercise mode, pre-exercise diet, and type of carbohydrate did not significantly affect the results of the meta-analysis.

1. The SDPooled was calculated as:
The Hedges’s correction (Hedges’s g) was used to account for potential bias due to the small sample
sizes that were used in the reviewed studies. To do this, the calculated standardized difference in means
and SDPooled were multiplied by the following correction factor:
In studies that reported more than one study outcome, an average of the study’s effect sizes/standard
errors were used in the calculation of the meta-analysis’ overall effect size. The overall effect size was
calculated using a random effects model. An effect size of zero would indicate that there is no difference
between the two treatments. A negative effect size would indicate that placebo yielded better
performance while a positive effect size would indicate that CHO mouth-rinse yielded better performance
outcomes. The reference points developed by Cohen (Cohen, 1988) were used for interpretation of the
effect sizes (effect size of 0.2 = small, 0.5 = moderate, 0.8 = large). To test if the type of performance
test utilized affected the effect size, an ANOVA-like procedure testing the between-group homogeneity
was employed. Meta regression was performed to assess the influence that potential moderator
variables had on effect size via mixed methods regression (method of moments) model. All calculations
were made with Comprehensive Meta Analysis, Version 2.2.064 (Biostat, Englewood, NJ).
• A systematic review and meta-analysis of the available literature indicated
that CHO mouth-rinse during endurance exercise results in an improved
endurance performance compared to control.
• The improvement appears to be independent of the type of control
utilized, CHO type, exercise mode, or pre-exercise dietary intake.
• Higher dose of the CHO may provide a greater performance effect,
however these results are based on a limited number of studies that
utilized higher CHO doses.
It has been well established that consuming carbohydrates (CHO) during
prolonged endurance exercise has a performance-enhancing effect. Over
the past ten years, a considerable body of evidence has suggested that CHO
may enhance exercise performance during moderate duration exercise due
stimulation of the central nervous system. To examine this theory, Carter et
al.2 found an improvement in performance when utilizing a CHO mouth-rinse
protocol during a one hour cycling time trial. Others studies were
subsequently published using a CHO mouth-rinse protocol. However, there
has been some discrepancy in the results.
The purpose of this investigation was objectively quantify via meta-analysis
if a CHO mouth-rinse can improve moderate duration endurance exercise
performance.
PURPOSE: Utilizing a systematic review of the literature combined with a meta-analysis, this investigation
sought to objectively assess the effect of a carbohydrate (CHO) mouth-rinse on endurance performance.
METHODS: PubMed, SportDiscus, ProQuest, and World Cat databases were searched using the key words:
carbohydrate AND mouth-rinse AND exercise OR performance. A total of 180 studies were identified by the
search terms. Inclusion criteria were as follows: 1) studies published in peer-reviewed journals, 2) use of
human subjects, 3) an endurance exercise bout of at least 10 minutes in duration, 4) a measure of exercise
performance, and 5) a CHO mouth-rinse and water/placebo condition. Data from each study were converted
into an effect size, i.e. standardized difference in means.
RESULTS: Sixteen studies met the inclusion criteria. The effect sizes for each study ranged from -0.52
(moderate effect tending to favor placebo) to 1.01 (very strong effect favoring CHO mouth-rise). The overall
effect size for the meta-analysis was 0.28 and was statistically significant (p = 0.001) indicating a small effect
size favoring CHO mouth-rinse. Study effect sizes were not significantly related to the length of pre-trial fast,
exercise mode, or type of CHO utilized. Studies that utilized a greater concentration of CHO in the mouth-rinse
demonstrated a significantly larger ES during the performance task (p = 0.01). However, these results were
based on a limited number of studies that used mouth-rinse solutions with greater than 6.4% CHO.
CONCLUSION: A meta-analysis of published literature indicated that utilizing a CHO mouth-rinse had a small
but significant effect on endurance exercise performance. Results may be related to the concentration of CHO
used in the mouth-rinse.
Scott A. Conger1, Matthew E. Darnell2, Scott M. Fulkerson1 (Sponsor: David R. Bassett, Jr., FACSM)
1 Boise State University, Boise, ID; 2 University of Pittsburgh, Pittsburgh, PA
DOES A CARBOHYDRATE MOUTH-RINSE IMPROVE
ENDURANCE EXERCISE PERFORMANCE?
.
.
.
Abstract
Background
Purpose
Methods
)1(2
2
,
,
22
CHOCON
CHOCONCHOCONCHOCON
R
SDSDRSDSD


POOLED
CONCHO
SD
 
PubMed, SportDiscus, ProQuest, and World Cat databases were
searched using the key words: carbohydrate AND mouth-rinse AND
exercise OR performance.
The criterion for inclusion in this meta-analysis was an endurance
exercise bout (>10 min), a measurement of exercise performance, and
CHO mouth-rinse and control conditions.
Data was converted into the standardized difference in means:
Literature Search
Inclusion Criteria
Statistical Analysis
  114
3
1
, 

CHOCONN
Summary of Studies
First Author, Year
Subjects
(M/F)
CHO
content (%)
Type of CHO
Control
Condition
Exercise
Mode
Endurance exercise
Carter, 2004 9 (7/2) 6.4 Maltodextrin Water
Cycle
Ergometer
Total time to complete 914 kJ
of work
Whitham, 2007 7 (7/0) 6 Maltodextrin Placebo Treadmill Total distance covered in 1 hr
Rollo, 2008 10 (10/0) 6 Glucose Placebo Treadmill
Total distance covered in 30
min
Chambers, 2009
Study A
8 (8/0) 6.4 Glucose Placebo
Cycle
Ergometer
Total work completed in 1 hr @
75% Wmax
Chambers, 2009
Study B
8 (6/2) 6.4 Maltodextrin Placebo
Cycle
Ergometer
Total work completed in 1 hr @
75% Wmax
Beeleen, 2009 14 (14/0) 6.4 Maltodextrin Water
Cycle
Ergometer
Total time to complete 1053 kJ
of work
Rollo, 2010 10 (10/0) 6.4 Glucose Placebo Treadmill Total distance covered in 1 hr
Pottier, 2010 12 (12/0) 6
Sucrose/
glucose
Placebo
Cycle
Ergometer
Total time to complete 975 kJ
of work
Fares, 2011 13 (13/0) 6.4 Maltodextrin Water
Cycle
Ergometer
Ride to exhaustion @ 60%
Wmax
Rollo, 2011 10 (10/0) 6.4 Glucose Placebo Treadmill Total distance covered in 1 hr
Sinclair, 2013 11 (11/0) 6.4 Maltodextrin Water
Cycle
Ergometer
Total distance covered in 30
min
Lane, 2013 12 (12/0) 10 Maltodextrin Placebo Bicycle Total work completed in 1 hr
Gam, 2013 10 (10/0) 6.4 Maltodextrin Water
Cycle
Ergometer
Total time to complete 1000 kJ
of work
Wright, 2013 7 (7/0) 6 & 12
Maltodextrin/
fructose
Placebo Treadmill
Total distance covered in 90
min
Muhamed, 2014 9 (9/0) 6
Sucrose/
glucose
Placebo
Cycle
Ergometer
30 min at 65% Wmax, then total
time to complete 10 km
Watson, 2014 10 (10,0) 6.4 Glucose Placebo
Cycle
Ergometer
Total work completed in 1 hr
Results
Results (cont.)
Conclusions
References
1. Beelen M, Berghuis J, Bonaparte B, Ballak SB, Jeukendrup AE, van Loon LJC. Carbohydrate
mouth rinsing in the fed state: Lack of enhancement of time-trial performance. Int J Sport Nutr
Exerc Metab. 2009; 19: 400-9.
2. Carter JM, Jeukendrup AE, Jones DA. The effect of carbohydrate mouth rinse on 1-h cycle time
trial performance. Med Sci Sport Exerc. 2004; 12: 2107-11.
3. Chambers ES, Bridge MW, Jones DA. Carbohydrate sensing in the human mouth: Effects on
exercise performance and brain activity. J Physiol. 2009; 587: 1779-94.
4. Fares EJ, Kayser B. Carbohydrate mouth rinse effects on exercise capacity in pre- and
postprandial states. J Nutr Metab. 2011; 6: 1-6.
5. Gam S, Guelfi KY, Fournier PA. Opposition of carbohydrate in a mouth-rinse solution to the
detrimental effect of mouth rinsing during cycling time trials. Int J Sport Nutr. 2013; 23: 48-56.
6. Lane SC, Bird SR, Burke LM, Hawley JA. Effect of a carbohydrate mouth rinse on simulated
cycling time-trial performance commenced in a fed or fasted state. Appl Physiol Nutr Metab. 2013;
38: 134-9.
7. Muhamed AMC, Mohamed NG, Ismail N, Aziz AR, Singh R. Mouth rinsing improves cycling
endurance performance during Ramadan fasting in a hot humid environment. Appl Physiol Nutr
Metab. 2014; 39: 458-64.
8. Pottier A, Bouckaert J, Gilis W, Derave W. Mouth rinse but not ingestion of a carbohydrate solution
improves 1-h cycle time trial performance. Scand J Med Sci Sport. 2010; 20: 105-11.
9. Rollo I, Williams C, Gant N, Nute M. The influence of carbohydrate mouth rinse on self-selected
speeds during a 30-min treadmill run. Int J Sport Nutr Exerc Metab. 2008; 18: 585-600.
10. Rollo I, Cole M, Miller R, Williams C. Influence of mouth rinsing a carbohydrate solution on 1-h
running performance. Med Sci Sport Exerc. 2010; 42: 798-804.
11. Rollo I, Williams C, Nevell M. Influence of ingesting versus mouth rinsing a carbohydrate solution
during a 1-h run. Med Sci Sport Exerc. 2011; 43: 468-75.
12. Sinclair J, Bottoms L, Flynn C, et al. The effect of different durations of carbohydrate mouth rinse
on cycling performance. Eur J Sport Sci. 2014; 14: 1-6.
13. Watson P, Nichols D, Cordery P. Mouth rinsing with a carbohydrate solution does not influence
cycle time trial performance in the heat. Appl Physiol Nutr Metab. 2014; 39: 1064-69.
14. Whitham M, McKinney J. Effect of a carbohydrate mouthwash on running time-trial performance. J
Sport Sci. 2007; 25: 1385-92.
15. Wright BF, Davison G. Carbohydrate mouth rinse improves 1.5 h run performance: Is there a
dose-effect? Int J Exerc Sci. 2013; 6: 328-40.
Moderator Variable p-value Comparison
Control condition 0.80
Placebo (N = 11, ES = 0.295, SEE = 0.108)
Water (N = 5, ES = 0.247, SEE = 0.159)
CHO dose 0.01
6-7% CHO (N=15, ES = 0.222, SE = 0.075)
10-12% (N=2, ES = 0.768, 0.204)
CHO Type 0.87
Glucose/Maltodextrin (N = 13, ES = 0.272, SEE = 0.100)
Multiple CHOs (N = 3, ES = 0.311, SEE = 0.208)
Exercise mode 0.61
Cycling (N = 11, ES = 0.311, SEE = 0.109)
Running (N = 5, ES = 0.211, SEE = 0.161)
Pre-exercise diet 0.66
Fed (N = 9, ES = 0.376, SEE = 0.123)
Fasted (N = 8, ES = 0.297, SEE = 0.132)
Effect of CHO mouth-rinse vs. control on Endurance Performance
Do the study characteristics explain the difference?
Forest plot with individual studies and overall (red diamond) effect sizes (Hedges’s g) for performance
with comparing control vs CHO mouth-rinse. Studies listed in ascending order of effect size.
Heterogeneity statistics revealed a Q value of 172.8 (df =15, p<0.001) indicating that the results were
unlikely to be a result of chance, I2 = 91.3 indicating that over 91% of the study-to-study dispersion was
due to real difference in the true effects.
ES: effect size (Hedges’s g), SEE: Standard error of estimate