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Tan SH, Khong TK, Selvanayagam VS, Yusof A. Central effects of mouth rinses on endurance and strength performance. Eur J Appl Physiol 2024; 124:403-415. [PMID: 38038740 DOI: 10.1007/s00421-023-05350-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 10/20/2023] [Indexed: 12/02/2023]
Abstract
Rinsing the mouth with a carbohydrate (CHO) solution has been shown to enhance exercise performance while reducing neuromuscular fatigue. This effect is thought to be mediated through the stimulation of oral receptors, which activate brain areas associated with reward, motivation, and motor control. Consequently, corticomotor responsiveness is increased, leading to sustained levels of neuromuscular activity prior to fatigue. In the context of endurance performance, the evidence regarding the central involvement of mouth rinse (MR) in performance improvement is not conclusive. Peripheral mechanisms should not be disregarded, particularly considering factors such as low exercise volume, the participant's fasting state, and the frequency of rinsing. These factors may influence central activations. On the other hand, for strength-related activities, changes in motor evoked potential (MEP) and electromyography (EMG) have been observed, indicating increased corticospinal responsiveness and neuromuscular drive during isometric and isokinetic contractions in both fresh and fatigued muscles. However, it is important to note that in many studies, MEP data were not normalised, making it difficult to exclude peripheral contributions. Voluntary activation (VA), another central measure, often exhibits a lack of changes, mainly due to its high variability, particularly in fatigued muscles. Based on the evidence, MR can attenuate neuromuscular fatigue and improve endurance and strength performance via similar underlying mechanisms. However, the evidence supporting central contribution is weak due to the lack of neurophysiological measures, inaccurate data treatment (normalisation), limited generalisation between exercise modes, methodological biases (ignoring peripheral contribution), and high measurement variability.Trial registration: PROSPERO ID: CRD42021261714.
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Affiliation(s)
- Shi Han Tan
- Faculty of Sports and Exercise Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Teng Keen Khong
- Faculty of Sports and Exercise Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Victor S Selvanayagam
- Faculty of Sports and Exercise Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Ashril Yusof
- Faculty of Sports and Exercise Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.
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Carbohydrate mouth rinse is no more effective than placebo on running endurance of dehydrated and heat acclimated athletes. Eur J Appl Physiol 2023:10.1007/s00421-023-05170-y. [PMID: 36920510 DOI: 10.1007/s00421-023-05170-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 02/27/2023] [Indexed: 03/16/2023]
Abstract
PURPOSE To determine whether carbohydrate mouth rinsing would improve endurance running performance of tropical natives in a warm-humid (30 °C and 70% relative humidity) environment. METHOD Twelve endurance male runners [age 25 ± 3 years; peak aerobic capacity ([Formula: see text]O2peak) 57.6 ± 3.6 mL.kg-1.min-1] completed three time-to-exhaustion (TTE) trials at ~ 70% [Formula: see text]O2peak while swilling 25 ml of a 6% carbohydrate (CHO) or taste-matched placebo (PLA) as well as no mouth rinse performed in the control (CON) trial. RESULTS TTE performance was significantly longer in both CHO and PLA trials when compared with the CON trial (54.7 ± 5.4 and 53.6 ± 5.1 vs. 48.4 ± 3.6 min, respectively; p < 0.001 and p = 0.012, respectively), but was not significantly different between CHO and PLA trials (p = 1.000). The rating of perceived exertion was not different between the CHO and PLA trials, however, was significantly affected when compared to the CON trial (p < 0.001). A similar effect was observed for perceived arousal level between the CHO and PLA trials to the CON trial. Core temperature, mean skin temperature and skin blood flow were not significantly different between the three trials (all p > 0.05). Similarly, plasma lactate and glucose as well as exercise heart rate were not influenced by the trials. CONCLUSIONS The present study demonstrates that mouth rinsing, whether carbohydrate or placebo, provides an ergogenic benefit to running endurance when compared to CON in a heat stress environment. Nevertheless, the results do not support the notion that rinsing a carbohydrate solution provides a greater advantage as previously described among non-heat acclimated individuals within a temperate condition.
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Hartley C, Carr A, Bowe SJ, Bredie WLP, Keast RSJ. Maltodextrin-Based Carbohydrate Oral Rinsing and Exercise Performance: Systematic Review and Meta-Analysis. Sports Med 2022; 52:1833-1862. [PMID: 35239154 PMCID: PMC9325805 DOI: 10.1007/s40279-022-01658-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2022] [Indexed: 12/04/2022]
Abstract
Background Carbohydrates are an important fuel for optimal exercise performance during moderate- and high-intensity exercise; however, carbohydrate ingestion during high-intensity exercise may cause gastrointestinal upset. A carbohydrate oral rinse is an alternative method to improve exercise performance in moderate- to high-intensity exercise with a duration of 30–75 min. This is the first systematic review and meta-analysis to comprehensively examine the isolated effect of maltodextrin-based rinsing on exercise performance. Objective The objective of this review was to establish the effect of a maltodextrin-based carbohydrate oral rinse on exercise performance across various modes of exercise. Furthermore, a secondary objective was to determine the effects of moderators [(1) participant characteristics; (2) oral rinse protocols; (3) exercise protocol (i.e. cycling, running etc.) and (4) fasting] on exercise performance while using a maltodextrin-based, carbohydrate oral rinse. Methods Five databases (MEDLINE, PsycINFO, Embase, SPORTDiscus and Global Health) were systematically searched for articles up to March 2021 and screened using Covidence (a systematic review management tool). A random effects robust meta-analysis and subgroup analyses were performed using Stata Statistical Software: Release 16. Results Thirty-five articles met the inclusion criteria and were included in the systematic review; 34 of these articles were included in the meta-analysis. When using a conventional meta-analytic approach, overall, a carbohydrate oral rinse improved exercise performance in comparison with a placebo (SMD = 0.15, 95% CI 0.04, 0.27; p = 0.01). Furthermore, when implementing an adjusted, conservative, random effects meta-regression model using robust variance estimation, overall, compared with placebo, a carbohydrate oral rinse demonstrated evidence of improving exercise performance with a small effect size (SMD = 0.17, 95% CI − 0.01, 0.34; p = 0.051). Conclusion This systematic review and meta-analysis demonstrates that a maltodextrin-based carbohydrate oral rinse can improve exercise performance. When comparing the two meta-analytic approaches, although non-significant, the more robust, adjusted, random effects meta-regression model demonstrated some evidence of a maltodextrin-based carbohydrate oral rinse improving exercise performance overall. Supplementary Information The online version contains supplementary material available at 10.1007/s40279-022-01658-3.
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Affiliation(s)
- Claudia Hartley
- CASS Food Research Centre, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Amelia Carr
- Centre for Sport Research, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Steven J Bowe
- Deakin Biostatistics Unit, Faculty of Health, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia
| | - Wender L P Bredie
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958, Frederiksberg, Denmark
| | - Russell S J Keast
- CASS Food Research Centre, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
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Evans ES, Brophy T, Braswell MR, Boyle J, Harris GK, Watkins RH, Bailey SP. Carbohydrate mouth rinsing does not affect 6-min walk test performance and blood glucose responses in older adults. Eur J Appl Physiol 2021; 121:2849-2858. [PMID: 34173862 DOI: 10.1007/s00421-021-04753-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 06/15/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE Carbohydrate (CHO) mouth rinsing (MR) prior to exercise has been shown to elicit enhanced performance and energy availability in some studies. Previous literature has concentrated on examining CHO MR strategies for improving aerobic endurance performance in younger athletic adults. Knowledge of the impact of CHO MR on functional performance in older adults is scarce. The purpose of this investigation was to determine if CHO MR would improve 6-min walk test (6MWT) performance, perceived exertion, and blood glucose responses in older adults. METHOD Thirty-three individuals (16 males, 17 females), age ≥ 70 years performed two 6MWT trials, one of which utilized a 6.4% maltodextrin CHO MR and one of which utilized a placebo MR. Participants held the MR in their mouth for 20 s prior to the 6MWT, and trials occurred in a counterbalanced fashion. Total distance walked and rating of perceived exertion (RPE) were recorded upon completion of each 6MWT. Heart rate (HR), peripheral blood oxygen saturation (SpO2), systolic and diastolic blood pressures (BP), blood glucose, and blood lactate were measured before and after each 6MWT. RESULT CHO MR did not alter the response of any study parameter compared to the placebo MR (p = 0.13-0.94). HR, systolic BP, and blood lactate increased and SpO2 decreased across time (p < 0.01). CONCLUSION A 6.4% maltodextrin CHO MR did not alter total distance walked, perceived exertion, or other physiological responses elicited by the 6MWT in older adults.
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Affiliation(s)
- Elizabeth S Evans
- Department of Physical Therapy Education, Elon University, 2085 Campus Box, Elon, NC, 27244, USA.
| | - Terrence Brophy
- Department of Physical Therapy Education, Elon University, 2085 Campus Box, Elon, NC, 27244, USA
| | - Matthew R Braswell
- Department of Physical Therapy Education, Elon University, 2085 Campus Box, Elon, NC, 27244, USA
| | - Joshua Boyle
- Department of Physical Therapy Education, Elon University, 2085 Campus Box, Elon, NC, 27244, USA
| | - G Keith Harris
- Department of Food, Bioprocessing, and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Ruth H Watkins
- Department of Food, Bioprocessing, and Nutrition Sciences, North Carolina State University, Raleigh, NC, USA
| | - Stephen P Bailey
- Department of Physical Therapy Education, Elon University, 2085 Campus Box, Elon, NC, 27244, USA
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Brietzke C, Franco-Alvarenga PE, Coelho-Júnior HJ, Silveira R, Asano RY, Pires FO. Effects of Carbohydrate Mouth Rinse on Cycling Time Trial Performance: A Systematic Review and Meta-Analysis. Sports Med 2020; 49:57-66. [PMID: 30488186 DOI: 10.1007/s40279-018-1029-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Despite the growing number of studies reporting carbohydrate mouth rinse effects on endurance performance, no systematic and meta-analysis review has been conducted to elucidate the level of evidence of carbohydrate mouth rinse effects on cycling trial performance such as time-, work-, and distance-based trials. OBJECTIVES The objective of this study were to establish the effect of a carbohydrate mouth rinse on cycling performance outcomes such as mean power output and time to complete a trial, together with the risk of bias in the cycling-carbohydrate mouth rinse literature. METHODS We systematically reviewed randomized placebo-controlled trials that assessed carbohydrate mouth rinse effects on mean power output and time to complete the trial. A random-effects meta-analysis assessed the standardized mean difference between carbohydrate and placebo mouth rinses. RESULTS Thirteen studies (16 trials) were qualitatively (systematic review) and quantitatively (meta-analysis) analyzed with regard to mean power output (n = 175) and time to complete the trial (n = 151). Overall, the reviewed studies showed a low risk of bias and homogeneous results for mean power output (I2 = 0%) and time to complete the trial (I2 = 0%). When compared with placebo, the carbohydrate mouth rinse improved mean power output (standardized mean difference = 0.25; 95% confidence interval 0.04-0.46; p = 0.02), but not the time to complete the trial (standardized mean difference = - 0.13; 95% confidence interval - 0.36 to 0.10; p = 0.25). CONCLUSION The present systematic and meta-analytic review supports the notion that a carbohydrate mouth rinse has the potential to increase mean power output in cycling trials, despite showing no superiority over placebo in improving time to complete the trials.
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Affiliation(s)
- Cayque Brietzke
- Exercise Psychophysiology Research Group, School of Arts, Sciences and Humanities, University of São Paulo, 1000 Arlindo Béttio Avenue, Ermelino Matarazzo, São Paulo, SP, 03828-000, Brazil
| | - Paulo Estevão Franco-Alvarenga
- Exercise Psychophysiology Research Group, School of Arts, Sciences and Humanities, University of São Paulo, 1000 Arlindo Béttio Avenue, Ermelino Matarazzo, São Paulo, SP, 03828-000, Brazil
| | - Hélio José Coelho-Júnior
- Applied Kinesiology Laboratory, University of Campinas, 701 Érico Veríssimo Avenue, Barão Geraldo, Campinas, SP, 13.083-851, Brazil
| | - Rodrigo Silveira
- Exercise Psychophysiology Research Group, School of Arts, Sciences and Humanities, University of São Paulo, 1000 Arlindo Béttio Avenue, Ermelino Matarazzo, São Paulo, SP, 03828-000, Brazil
| | - Ricardo Yukio Asano
- Exercise Psychophysiology Research Group, School of Arts, Sciences and Humanities, University of São Paulo, 1000 Arlindo Béttio Avenue, Ermelino Matarazzo, São Paulo, SP, 03828-000, Brazil
| | - Flávio Oliveira Pires
- Exercise Psychophysiology Research Group, School of Arts, Sciences and Humanities, University of São Paulo, 1000 Arlindo Béttio Avenue, Ermelino Matarazzo, São Paulo, SP, 03828-000, Brazil.
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