Article

The Effect of Carbohydrate Mouth Rinse on 1-h Cycle Time Trial Performance

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Abstract

To investigate the possible role of carbohydrate (CHO) receptors in the mouth in influencing exercise performance, seven male and two female endurance cyclists (VO(2max) 63.2 +/- 2.7 (mean +/- SE) mL.kg*(-1).min(-1)) completed two performance trials in which they had to accomplish a set amount of work as quickly as possible (914 +/- 40 kJ). On one occasion a 6.4% maltodextrin solution (CHO) was rinsed around the mouth for every 12.5% of the trial completed. On the other occasion, water (PLA) was rinsed. Subjects were not allowed to swallow either the CHO solution or water, and each mouthful was spat out after a 5-s rinse. Performance time was significantly improved with CHO compared with PLA (59.57 +/- 1.50 min vs 61.37 +/- 1.56 min, respectively, P = 0.011). This improvement resulted in a significantly higher average power output during the CHO compared with the PLA trial (259 +/- 16 W and 252 +/- 16 W, respectively, P = 0.003). There were no differences in heart rate or rating of perceived exertion (RPE) between the two trials (P > 0.05). The results demonstrate that carbohydrate mouth rinse has a positive effect on 1-h time trial performance. The mechanism responsible for the improvement in high-intensity exercise performance with exogenous carbohydrate appears to involve an increase in central drive or motivation rather than having any metabolic cause. The nature and role of putative CHO receptors in the mouth warrants further investigation.

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... Compared to traditional CHO drink ingestion, rinsing protocols may provide comparable performance improvements during endurance exercise (Pottier et al., 2010). A landmark study conducted by Carter et al. (2004) demonstrated a CHO rinse (6.4% maltodextrin solution) elicited a 2.9% improvement in a cycling trial of endurance trained cyclists. These findings have led to an increased popularity of CHO rinsing as a supplementation strategy in endurance sports, especially in those in which athletes experience gastrointestinal distress with CHO ingestion (Jeukendrup et al., 2013). ...
... These findings have led to an increased popularity of CHO rinsing as a supplementation strategy in endurance sports, especially in those in which athletes experience gastrointestinal distress with CHO ingestion (Jeukendrup et al., 2013). However, several follow-up studies reported equivocal findings in performance improvements using a CHO rinse, with most positive findings occurring in endurance exercise of approximately one-hour in duration (Carter et al., 2004(Carter et al., , 2016James et al., 2017;Pottier et al., 2010). Furthermore, whether CHO rinsing provides residual benefits in subsequent exercise bouts or Journal of Human Kinetics -volume 83/2022 http://www.johk.pl ...
... Participants rinsed their mouths with either a commercially available CHO drink (Powerade ® , Fruit Punch) or an artificially (Pottier et al., 2010). The concentration of the CHO solution selected for this study was 6.4%, which has been shown to improve performance (Carter et al., 2004;Chambers et al., 2009;Pottier et al., 2010) and diminished response to higher concentrations (Devenney et al., 2016;James et al., 2017). Artificial sweeteners have been used as a control solution in previous studies (Kumar et al., 2016;Pottier et al., 2010). ...
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The purpose of the study was to examine the effects of carbohydrate (CHO) mouth rinsing on autonomic and metabolic recovery as well as cycling performance. Ten male recreational cyclists (age = 30 ± 6 years, VO 2peak = 54.5 ± 8.1 mL·kg ⁻¹ ·min ⁻¹ ) completed a randomized, double-blind, placebo-controlled, crossover designed study. A CHO or a placebo (PLA) rinse was administered every 12.5% of a work to completion trial (75%W max ). Heart rate variability (lnRMSSD), the respiratory exchange ratio, and plasma epinephrine, norepinephrine, insulin, glucose, free fatty acids (FFA), and lactate were measured pre- and post-exercise. The CHO rinse did not improve time to completion of the test trial (CHO: 4108 ± 307 s, PLA: 4176 ± 374 s, p = 0.545). Further, the CHO rinse did not impact autonomic recovery, as measured by lnRMSSD (p = 0.787) and epinephrine (p = 0.132). Metabolic biomarkers were also unaffected by the CHO rinse, with no differences observed in responses of FFA (p = 0.064), lactate (p = 0.302), glucose (p = 0.113) or insulin (p = 0.408). Therefore, the CHO mouth rinse does not reduce the acute sympathetic response following strenuous exercise and does not result in improvements in cycling time to completion.
... During the time trial, participants were instructed to complete a certain amount of work (kJ) as quickly as possible. This amount of work was based on a formula including each participant's maximum power output value (W max ) [28]. During the time trial either a 6.4% (w/v) maltodextrin or water (placebo) sample was rinsed in the mouth for 5 s prior to expectoration. ...
... During the time trial either a 6.4% (w/v) maltodextrin or water (placebo) sample was rinsed in the mouth for 5 s prior to expectoration. With the carbohydrate oral rinse, performance time was significantly faster (2.9%) in comparison with the water rinse (placebo) [28]. Additionally, improvements in exercise performance after an oral carbohydrate rinse in comparison with a placebo rinse have been found with cycling [29][30][31][32][33], running [34][35][36][37] and resistance exercise [38]. ...
... Furthermore, research in this area has also discussed a possible placebo effect in conjunction with carbohydrate oral rinsing. As previous research has demonstrated that placebo effects may have a significant impact on physical performance [47], it is common practice for at least two oral rinses to be trialled: a carbohydrate oral rinse and a placebo oral rinse [28,29]. To minimise possible placebo effects between the rinsing conditions, previous research has also blinded participants to the composition of the rinses and also to the true objective of the experiment [45]. ...
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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.
... Over the past 15 years mouth rinsing has been suggested to mitigate fatigue during a range of activities, including endurance (Carter et al., 2004), intermittent (Rollo et al., 2015)and strength-based exercises (Decimoni et al., 2018). Specifically, mouth rinsing with carbohydrate (CHOMR) is suggested to exert its ergogenic effect via activation of the brain regions associated with reward and pleasure (anterior cingulate cortex and ventral striatum; Chambers et al., 2009), motor output (sensorimotor cortex) and visual cue perception (intracalcarine and temporal occipital fusiform cortices; Turner et al., 2014)). ...
... Signaling pathways are also activated by CHOMR, which in turn, are suggested to enhance corticomotor output (facial, glossopharyngeal and vagus afferent pathways; Gant et al., 2010). The beneficial effect of CHOMR was first reported on 1 h cycling time trial (TT) performance (Carter et al., 2004). Since then, its effect has been explored on other types of exercises including continuous and intermittent running (Rollo et al., 2008(Rollo et al., , 2015, single and repeated sprints (Chong et al., 2011) and soccer specific performance (Matsumoto, 2013) (Arlai & Nana, 2019). ...
... This claim should be interpreted with caution, however, as this study did not examine brain responses other than perceptual feelings of RPE, FAS and FS. Importantly, the current study did not find any significant changes in any of these perceptual brain-linked responses for any mouth rinse, which previous studies corroborate (Rollo et al., 2008;Rollo et al., 2010;Carter et al., 2004). The lack of difference observed in the present study could be attributed to the near-maximal RPE values elicited by RSAT, and as a result, this created a 'ceiling effect' that makes any significant difference between treatments hard to distinguish (Beaven et al., 2013). ...
Article
The study examined the synergistic and independent effects of carbohydrate-caffeine mouth rinse on repeated sprint performance during simulated soccer match play. Nine male soccer players (21 ± 3 years, 1.75 ± 0.05 m, 68.0 ± 9.0 kg) completed four trials with either 6 mg·kg⁻¹ caffeine + 10% maltodextrin (CHO+CAFMR), 6 mg·kg⁻¹ caffeine (CAFMR), 10% maltodextrin (CHOMR), water (PLA) in a block randomised, double-blinded, counterbalanced and crossover manner separated by minimum 96 h. All solutions were taste-matched and a carbohydrate-rich meal (2 g·kg⁻¹body mass) was provided a minimum 2 h before each trial. Each trial consisted of a 90-min soccer specific aerobic field test (SAFT⁹⁰) and two bouts of repeated sprint ability tests (RSAT; 6 x 6 s sprints with 24 s recovery) completed at 0 min and 75th min of SAFT⁹⁰. A 25 ml solution of either CHO+CAFMR, CAFMR, CHOMR or PLA was rinsed immediately before the second RSAT (75 min). Mean power output, peak power output (PPO) or fatigue index (FI) was not impacted by any treatment during the 75th min RAST (p > 0.05). These results suggest that carbohydrate and/or caffeine mouth rinses do not have an ergogenic effect during simulated soccer exercise after a high carbohydrate meal.
... Carbohydrate (CHO) mouth rinsing has been touted as a nutritional strategy to improve exercise performance (Jeukendrup, 2013). The strategy consists of rinsing a CHO beverage for ∼10 s in the oral cavity without swallowing (Jeukendrup, 2013), and studies have suggested that the contact of CHO with the oral mucosa activates receptors that are linked to activation of the central nervous system and reward system (Carter et al., 2004), which may improve performance (Jeukendrup, 2013). However, current evidence as to the efficacy of CHO mouth rinse on performance is conflicting as some studies show positive effects (Carter et al., 2004;Rollo et al., 2008Rollo et al., , 2010, whereas others do not (Cherif et al., 2018;Dolan et al., 2017;Dorling & Earnest, 2013;Rossato et al., 2019;Whitham & McKinney, 2007). ...
... The strategy consists of rinsing a CHO beverage for ∼10 s in the oral cavity without swallowing (Jeukendrup, 2013), and studies have suggested that the contact of CHO with the oral mucosa activates receptors that are linked to activation of the central nervous system and reward system (Carter et al., 2004), which may improve performance (Jeukendrup, 2013). However, current evidence as to the efficacy of CHO mouth rinse on performance is conflicting as some studies show positive effects (Carter et al., 2004;Rollo et al., 2008Rollo et al., , 2010, whereas others do not (Cherif et al., 2018;Dolan et al., 2017;Dorling & Earnest, 2013;Rossato et al., 2019;Whitham & McKinney, 2007). To date, it has been suggested that the ergogenic effect of CHO mouth rinse is most likely to occur in sports consisting of continuous exercise with a duration between 30 and 60 min (Best et al., 2021;Carter et al., 2004;Jeukendrup, 2013;Pottier et al., 2010;Rollo et al., 2010). ...
... However, current evidence as to the efficacy of CHO mouth rinse on performance is conflicting as some studies show positive effects (Carter et al., 2004;Rollo et al., 2008Rollo et al., , 2010, whereas others do not (Cherif et al., 2018;Dolan et al., 2017;Dorling & Earnest, 2013;Rossato et al., 2019;Whitham & McKinney, 2007). To date, it has been suggested that the ergogenic effect of CHO mouth rinse is most likely to occur in sports consisting of continuous exercise with a duration between 30 and 60 min (Best et al., 2021;Carter et al., 2004;Jeukendrup, 2013;Pottier et al., 2010;Rollo et al., 2010). However, its effects on intermittent exercise, such as soccer, are less well studied. ...
Article
Carbohydrate (CHO) mouth rinsing seems to improve performance in exercises lasting 30-60 min. However, its effects on intermittent exercise are unclear. It is also unknown whether serial CHO mouth rinses can promote additional ergogenic effects when compared with a single mouth rinse. The aim of this study was to evaluate the effect of single and serial CHO mouth rinses on Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) performance in soccer players. In a randomized, crossover, double-blind, placebo-controlled design, 12 male (18.9 ± 0.5 years) soccer players performed eight serial mouth rinses under three different conditions: placebo solution only (noncaloric juice), seven placebo mouth rinses plus a single CHO mouth rinse (8% maltodextrin), or eight CHO mouth rinses (8-CHO). Following the final mouth rinse, individuals performed the Yo-Yo IR1 test to evaluate the maximal aerobic endurance performance measured via total distance covered. There were no differences in Yo-Yo IR1 performance between sessions (p = .32; single CHO mouth rinse (8% maltodextrin): 1,198 ± 289 m, eight CHO mouth rinses: 1,256 ± 253 m, placebo: 1,086 ± 284 m). In conclusion, single and serial CHO mouth rinsing did not improve performance during the Yo-Yo IR1 for soccer players. These data suggest that CHO mouth rinsing is not an effective ergogenic strategy for intermittent exercise performance irrespective of the number of rinses.
... Although comparison between the conditions did not reach significance for the other main dependent variables (peak acceleration, peak velocity, peak horizontal force, and average velocity), clear beneficial effects of CAF-CHO were observed for peak horizontal force in Sprint 2 relative to NMR (d: 0.78) and PLA (d: 0.70), and also expectoration [6,8,11]. For the NMR control trial, no fluid was provided. ...
... Previous research has demonstrated the potential for rapid central effects of caffeine to impact on exercise performance [14]. Earlier investigations have similarly proposed central stimulation as the underlying mechanism of mouth-rinsing (i.e., CHO), which involves triggering of receptors located in the mouth [11,13]. CAF mouth-rinsing activates the receptor cells (oropharyngeal epithelia) in the oral cavity, activating gustatory (i.e., taste) neural pathways to stimulate the same brain regions responsible for reward and information processing [28]. ...
... To date, CHO mouth-rinsing has yielded up to 12% improvement in cycling and endurance performances when compared to PLA or NMR conditions in Ramadan-fasting subjects [6,10]. The performance improvement in biomechanical parameters in the present study are also consistent with the previous literatures that showed positive effects following a mouth-rinsing intervention [6,7,10,11,12,18,25]. A recent fasting study, however, found no statistically significant main effect of CHO mouthrinsing on average power, average speed, and vertical stiffness during an interval sprinting protocol (2 sets of 5 × 5 s each, 25 s and 3 min recovery in-between sprints and sets, respectively), when comparing PLA and NMR [30]. ...
Article
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Carbohydrate mouth-rinsing has been reported to benefit endurance performance in athletes intermittently fasting; however, in the fasted state, the effects of combined caffeine and carbohydrate (CAF-CHO) mouth-rinsing on sprint-endurance performance are unknown. We determined the effects of CAF-CHO mouth-rinsing on kinetics, kinematics, and perceptual measures during a sprint-endurance performance commonly performed by track and field athletes in Muslim athletes fasting during Ramadan. In a randomised and counterbalanced single-blind study, ten national-level male sprinters and sprint/middle-distance runners (21.0±2.0 y) participated in this study. They performed three sprint-endurance sessions on a non-motorised treadmill within the second and third weeks of Ramadan. Each session consisted of 3x15-s all-out sprints, with 2-min active recovery between each sprint. In each session, athletes either did not mouth rinse (NMR), or rinsed with 25 mL of CAF-CHO (4 g carbohydrate, 5 mg caffeine), or a placebo solution (PLA) prior to warm-up (30-min pre-trial), 1-min pre-trial, and mid-way through every recovery period. CAF-CHO maximised total sprint distance relative to NMR (210.3±7.8 vs. 208.7±9.1 m, d=0.20), whilst counteracted the attenuation following PLA (204.6±8.7 m; d=0.66). Relative to NMR, CAF-CHO increased perceived activation prior to each sprint (p<0.05, d=1.23-2.05). Post-trial perceived exertion was lower for CAF-CHO (d=0.12) and PLA (d=0.58) compared to NMR (p>0.05). Athletes indicated ‘no’ (50%) or ‘unsure’ (50%) whether mouth-rinsing would improve performance. The results suggest that CAF-CHO has a potential to optimise, and counter-act the negative effect of mouth-rinsing in Ramadan-fasted Muslims having a negative attitude towards this procedure. Keywords: Athletics, ergogenic aid, perceived activation, Ramadan, sprint training
... For example, when comparing CHO ingestion relative to CAF, it has been suggested that CHO should be ingested at a rate of 1 g/min, or in sufficient amounts, 30 min before fatigue (23), whereas CAF should be consumed 1 h before fatigue as this will allow for plasma CAF concentrations to peak (22). Albeit the positive effects of dietary supplementation during exercise, the ergogenic effects may not be directly proportional to peak oxidation or concentration (24). In light of this, evidence suggests that rinsing of the oral cavity may be used to improve performance through activation of chemoreceptors and thermoreceptors, leading to an increase in brain activity (25,26). ...
... During exercise, it has been suggested that oral receptors within the mouth directly stimulate reward centers in the brain, which increase "central drive" and improve work capacity: this has been observed in CHO, CAF, and MEN MRs (11,24,(40)(41)(42)(43)(44). The activation of reward areas in the brain, such as the insula/frontal operculum, orbitofrontal cortex, and striatum, is suggested to lower the perception of exertion during exercise (11,45) and, potentially, feelings of displeasure (46). ...
... This implies that MEN is effective at reducing thermal sensation and/or state via its action on the trigeminal ganglion, which may contribute to increased skeletal muscle activation during hyperthermic exercise (60). Moreover, it has been suggested that, when MEN stimulates the trigeminal system, this directly activates reward/pleasure centers in the brain to increase "central drive" and improve work capacity (11,24,40,(42)(43)(44). The activation of reward areas in the brain, such as the insula/frontal operculum, the orbitofrontal cortex, and the striatum, is suggested to lower the perception of exertion during exercise (11,45) and, potentially, feelings of displeasure (46). ...
Article
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Interventions that solely act on the central nervous system (CNS) are gaining considerable interest, particularly products consumed through the oral cavity. The oropharyngeal cavity contains a wide array of receptors that respond to sweet, bitter, and cold tastants, all of which have been shown to improve physiological performance. Of late, the ergogenic benefits of carbohydrate (CHO) and caffeine (CAF) mouth rinsings (MRs) have been widely studied; however, less is known about menthol (MEN). That the physiological state and environmental conditions impact the response each product has is increasingly recognized. While the effects of CHO and CAF MRs have been thoroughly studied in both hot and thermoneutral conditions, less is known about MEN as it has only been studied in hot environments. As such, this review summarizes the current knowledge regarding the MEN MR and exercise modality, frequency of the mouth rinse, and mouth rinse duration and compares two different types of study designs: time trials vs. time to exhaustion (TTE).
... Mouth swilling is an increasingly popular ergogenic strategy employed by athletes over a short to moderate exercise duration [1][2][3][4][5][6], during nutrient restricted states [7][8][9][10] and may be appropriate during times of potential gastrointestinal distress [11,12]. Multiple nutritional stimuli are swilled, each conferring a different ergogenic effect [5,6,13,14] and magnitude thereof, most likely due to affecting differing sensory pathways. ...
... Carbohydrate (CHO) is considered the gold standard ergogenic mouth swilling strategy, with a wealth of literature documenting its efficacy in contrasting environments [21], nutritional states [9] and sports [22][23][24]. Mechanistically, CHO is shown to activate areas of the brain that are associated with behavioural, cognitive and emotional responses [3], with areas associated with motivation and motor control also stimulated [25]. The activation of these higher order and efferent regions of the brain, as supported by functional magnetic resonance imaging (fMRI), provide strong explanation(s) for CHO mouth swilling's ergogenic effects to date, but CHO is also shown to affect receptors within the oral cavity [26], as are caffeine [27][28][29] and menthol [13,30,31]. ...
... Similarly, the duration between swills warrants attention, as if swills are administered too close together, and receptors may still be saturated and thus sensations may be falsely heightened, thus committing a type 1 error. This is likely cause for concern when swilling menthol, however, it could also apply to other tastants such as caffeine, capsaicin or quinine [15] and sweet carbohydrates [1][2][3][4][5][6][7]15]. ...
Article
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Carbohydrate and menthol mouth-swilling have been used to enhance exercise performance in the heat. However, these strategies differ in mechanism and subjective experience. Participants (n = 12) sat for 60 min in hot conditions (35 °C; 15 ± 2%) following a 15 min control period, during which the participants undertook three 15 min testing blocks. A randomised swill (carbohydrate; menthol; water) was administered per testing block (one swill every three minutes within each block). Heart rate, tympanic temperature, thermal comfort, thermal sensation and thirst were recorded every three minutes. Data were analysed by ANOVA, with carbohydrate intake controlled for via ANCOVA. Small elevations in heart rate were observed after carbohydrate (ES: 0.22 ± 90% CI: −0.09-0.52) and water swilling (0.26; −0.04-0.54). Menthol showed small improvements in thermal comfort relative to carbohydrate (−0.33; −0.63-0.03) and water (−0.40; from −0.70 to −0.10), and induced moderate reductions in thermal sensation (−0.71; from −1.01 to −0.40 and −0.66; from −0.97 to −0.35, respectively). Menthol reduced thirst by a small to moderate extent. These effects persisted when controlling for dietary carbohydrate intake. Carbohydrate and water may elevate heart rate, whereas menthol elicits small improvements in thermal comfort, moderately improves thermal sensation and may mitigate thirst; these effects persist when dietary carbohydrate intake is controlled for.
... The first mouth rinsing experiment was performed in 2004 by Carter and colleagues 89 where they showed stimulation of sweet taste receptors in the oral cavity, which activated various reward centers in the brain 87,90 . Importantly, in the same timeframe, it was also confirmed that carbohydrate mouth rinsing did not alter plasma glucose concentrations, suggesting the ergogenic effect must be mediated by the central nervous system 91 . ...
... Importantly, in the same timeframe, it was also confirmed that carbohydrate mouth rinsing did not alter plasma glucose concentrations, suggesting the ergogenic effect must be mediated by the central nervous system 91 . To date, most studies exploring the effect of carbohydrate mouth rinsing on athletic performance have produced consistent findings, supporting a positive ergogenic effect [81][82][83]89 . ...
Article
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Top-class athletes have optimized their athletic performance largely through adequate training, nutrition, recovery, and sleep. A key component of sports nutrition is the utilization of nutritional ergogenic aids, which may provide a small but significant increase in athletic performance. Over the last decade, there has been an exponential increase in the consumption of nutritional ergogenic aids, where over 80% of young athletes report using at least one nutritional ergogenic aid for training and/or competition. Accordingly, due to their extensive use, there is a growing need for strong scientific investigations validating or invalidating the efficacy of novel nutritional ergogenic aids. Notably, an overview of the physiological considerations that play key roles in determining ergogenic efficacy is currently lacking. Therefore, in this brief review, we discuss important physiological considerations that contribute to ergogenic efficacy for nutritional ergogenic aids that are orally ingested including: (1) the impact of first pass metabolism, (2) rises in systemic concentrations, and (3) interactions with the target tissue. In addition, we explore mouth rinsing as an alternate route of ergogenic efficacy that bypasses the physiological hurdles of first pass metabolism via direct stimulation of the central nervous system. Moreover, we provide real world examples and discuss several practical factors that can alter the efficacy of nutritional ergogenic aids including human variability, dosing protocols, training status, sex differences, and the placebo effect. Taking these physiological considerations into account will strengthen the quality and impact of the literature regarding the efficacy of potential ergogenic aids for top-class athletes.
... Indeed, isolated oral exposure to CHO through mouth-rinsing (MR) has demonstrated small to moderate positive effects on exercise performance in short-term (< 60 min), steady-state high-intensity (> 75% VO 2 max) running and cycling. Relative to taste-matched placebo solutions (PLA), CHO MR was observed to improve time trial (TT) performance and power production, as well as increase distances and times to exhaustion (18)(19)(20). In seminal work, direct infusion of glucose did not enhance exercise performance, despite elevated blood glucose levels and increased muscle glucose uptake (21). ...
... The absence of diverging RPE values between CHO and PLA MR with the development of physical fatigue opposes previous CHO-ingestion ice-hockey research (15)(16)(17). However, this observation has been frequently repeated in existing CHO MR exercise research (18)(19)(20). The present findings along with others demonstrate that instead of reducing perceptions of effort and fatigue, oral sensing of CHO permits maintenance of these perceptions despite greater work performed. ...
... Indeed, isolated oral exposure to CHO through mouth-rinsing (MR) has demonstrated small to moderate positive effects on exercise performance in short-term (< 60 min), steady-state high-intensity (> 75% VO 2 max) running and cycling. Relative to taste-matched placebo solutions (PLA), CHO MR was observed to improve time trial (TT) performance and power production, as well as increase distances and times to exhaustion (18)(19)(20). In seminal work, direct infusion of glucose did not enhance exercise performance, despite elevated blood glucose levels and increased muscle glucose uptake (21). ...
... The absence of diverging RPE values between CHO and PLA MR with the development of physical fatigue opposes previous CHO-ingestion ice-hockey research (15)(16)(17). However, this observation has been frequently repeated in existing CHO MR exercise research (18)(19)(20). The present findings along with others demonstrate that instead of reducing perceptions of effort and fatigue, oral sensing of CHO permits maintenance of these perceptions despite greater work performed. ...
Article
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PurposeThis randomized, double-blind, crossover study examined the effects of mouth-rinsing (MR) with a carbohydrate (CHO) vs. a placebo (PLA) solution on external and internal loads in hydrated ice hockey players during regulation and overtime (OT) periods of an on-ice scrimmage.Methods Twelve skilled male hockey players (22.6 [3.4] years, 178.9 [4.7] cm, 84.0 [6.5] kg) played three 20-min regulation periods and one 12-min OT period of small-sided 3-on-3 scrimmage. Skaters repeated 2 min shift and rest intervals. Participants mouth rinsed with 25 mL of CHO or PLA solution approximately every 10 min for a total of 7 rinses. A local positioning system (LPS) tracked external load variables including speed, distance, acceleration, and deceleration. Internal load was monitored with heart rate (HR) sensors and a rating of perceived exertion (RPE).ResultsDuring regulation play, both the conditions developed similar fatigue, with significantly decreased high-intensity distance, average speed and decelerations, and increased RPE, from period 1 to 2 and 3. In OT, CHO MR increased the distance skated at high-intensity (224 [77], 185 [66] m, p = 0.042), peak speed (24.6 [1.6], 23.7 [1.3] km·h−1, p = 0.016), number of sprints (1.9 [1.2], 1.2 [0.9], p = 0.011), and decreased distance skated at slow speed (300 [33], 336 [47], p = 0.034) vs. PLA MR. OT RPE was similar between the two conditions in spite of more work done in CHO MR.ConclusionsCHO MR may be a valuable practice to protect against decrements in external load with increased playing time in ice hockey, and possibly allows athletes to perform more work relative to perceived levels of exertion.
... The training itself, performed in all 4 cases under the same conditions (same load, intensity, and duration) modifies this perception, and it seems that the intake of different solutions and rinsing is not sufficient to cause differences between subjective perceptions. Previous research has shown significant improvements in the intake of placebo rinse or CH rinse [26][27][28]; however, the results obtained do not follow the same line. addition, it should be used by sport psychologists, physical trainers, and coaches to promote the peak performance of these athletes and decrease attrition [24]. ...
... The training itself, performed in all 4 cases under the same conditions (same load, intensity, and duration) modifies this perception, and it seems that the intake of different solutions and rinsing is not sufficient to cause differences between subjective perceptions. Previous research has shown significant improvements in the intake of placebo rinse or CH rinse [26][27][28]; however, the results obtained do not follow the same line. FS ratings ( Figure 2) decreased over time in group B (from 2.89 ± 1.76 to 2.44 ± 2.46) and increased in group A (from 2.22 ± 1.64 to 3.33 ± 1.41), group C (from 3 ± 1.66 to 3.78 ± 1.3), and group D (from 3 ± 1.22 to 2.78 ± 2.33). ...
Article
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Triathlons are endurance events that include swimming, running, and cycling. Triathletes need to eat optimally during training and competitions to maximize their potential for success. The presence of carbohydrates in the mouth could activate regions in the brain to enhance athletic performance in exercise. Methods: This study examined the effects of glucose and mouthwash in ten male triathletes (age: 26.0 ± 8.7 years, height: 173.6 ± 10.4 cm, BMI 22.0 ± 1.7 kg/m2). The four oral test solutions included (A) Rinse with placebo, (B) Water + gel with placebo, (C) Rinse with 15% CH concentration, and (D) Water + gel with 15% CH concentration (25 g gel in 165 mL water). The Rate of Perceived Exertion (RPE), Sensation Scale (FS), Felt Arousal Scale (FAS), Profile of Mood States (POMS), blood glucose, sprints, and dietary habits were assessed in each subject. All preceded ingestion of the oral-based test solution during workouts. Results: RPE showed no significant differences for subjective perceptions. The same was observed for FS and sprints. FAS scores increased over time (p = 0.039) in all groups. POMS score increased significantly in group D (p = 0.041). There was no effect of time on plasma glucose levels (p = 0.737). As for correlations, positive correlations were observed between sprint and FAS variables (p = 0.011). Conclusions: It appears that CH intake correlates positively with mood, but in all other variables, there are no differences depending on the product.
... to be ergogenic, but complement existing carbohydrate swilling literature of similar exercise durations [44][45][46]. ...
... This suggests that during extended self-paced exercise in the heat, fuel availability and associated oral sensing may be a more dominant signal than thermal perception when swills are applied at regular intervals throughout the exercise bout. These findings are contrary to previous research in shorter duration [22,40] and fixedpaced exercise [41][42][43] in the heat, where menthol administration has been shown to be ergogenic, but complement existing carbohydrate swilling literature of similar exercise durations [44][45][46]. ...
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The current study compared mouth swills containing carbohydrate (CHO), menthol (MEN) or a combination (BOTH) on 40 km cycling time trial (TT) performance in the heat (32 • C, 40% humidity, 1000 W radiant load) and investigates associated physiological (rectal temperature (Trec), heart rate (HR)) and subjective measures (thermal comfort (TC), thermal sensation (TS), thirst, oral cooling (OC) and RPE (legs and lungs)). Eight recreationally trained male cyclists (32 ± 9 y; height: 180.9 ± 7.0 cm; weight: 76.3 ± 10.4 kg) completed familiarisation and three experimental trials, swilling either MEN, CHO or BOTH at 10 km intervals (5, 15, 25, 35 km). The 40 km TT performance did not differ significantly between conditions (F 2,14 = 0.343; p = 0.715; η 2 = 0.047), yet post-hoc testing indicated small differences between MEN and CHO (d = 0.225) and MEN and BOTH (d = 0.275). Subjective measures (TC, TS, RPE) were significantly affected by distance but showed no significant differences between solutions. Within-subject analysis found significant interactions between solution and location upon OC intensity (F 28,196 = 2.577; p < 0.001; η 2 = 0.269). While solutions containing MEN resulted in a greater sensation of OC, solutions containing CHO experienced small improvements in TT performance. Stimulation of central CHO pathways during self-paced cycling TT in the heat may be of more importance to performance than perceptual cooling interventions. However, no detrimental effects are seen when interventions are combined.
... While debate persists (Brietzke et al., 2019;Li et al., 2019;Borszcz & de Lucsa, 2020), mouth-rinsing with a carbohydrate solution has been proposed as a potential ergogenic practice for improving endurance exercise performance (Carter et al., 2004;Chambers et al., 2009;Lane et al., 2013;Pottier et al., 2010;Rollo et al., 2011). It is proposed that the presence of carbohydrate in the oral cavity stimulates oropharyngeal receptors, eliciting a central neural response and resulting in enhanced central drive for increased or sustained work output (Carter et al., 2004;Jeukendrup & Chambers, 2010), via activation of brain regions associated with reward (Chambers et al., 2009). ...
... While debate persists (Brietzke et al., 2019;Li et al., 2019;Borszcz & de Lucsa, 2020), mouth-rinsing with a carbohydrate solution has been proposed as a potential ergogenic practice for improving endurance exercise performance (Carter et al., 2004;Chambers et al., 2009;Lane et al., 2013;Pottier et al., 2010;Rollo et al., 2011). It is proposed that the presence of carbohydrate in the oral cavity stimulates oropharyngeal receptors, eliciting a central neural response and resulting in enhanced central drive for increased or sustained work output (Carter et al., 2004;Jeukendrup & Chambers, 2010), via activation of brain regions associated with reward (Chambers et al., 2009). ...
Article
Ageing is associated with reductions in appetite and food intake leading to unintentional weight loss. Such weight loss, particularly through muscle mass reduction, is associated with muscle weakness and functional decline, which represent predictors of poor health outcomes and contribute to frailty in older adults. Exercise-induced anorexia is an established phenomenon in young adults; however appetite and energy intake (EI) responses to resistance exercise are unknown in older adults. Twenty healthy older adults (68 ± 5 years, BMI 26.2 ± 4.5 kg.m-2) undertook two 5-hour experimental trials. Participants rested for 30 minutes before being provided with a standardised breakfast (196 kcal, 75.2% carbohydrate, 8.9% protein and 15.9% fat). Participants then rested for 1-hour before completing: 1-hour resistance exercise bout followed by 2-hour of rest (RE) or, a control condition (CON) where participants rested for 3 hours, in a randomised crossover design. Appetite perceptions were measured throughout both trials and on cessation, an ad libitum meal was provided to assess EI. A repeated-mesures ANOVA revealed no significant condition x time interaction for subjective appetite (p = 0.153). However, area under the curve for appetite was significantly lower in the RE compared with CON (49 ± 8mm•hour-1 vs. 52 ± 9mm•hour-1, p = 0.007, d = 0.27). There was no difference in EI (RE = 681 ± 246 kcal; CON = 673 ± 235 kcal; p = 0.865), suggesting that resistance exercise does not affect EI 2 hours post-exercise in older adults despite a significant but modest reduction in appetite over a 5-h period. In conclusion, resistance exercise may be an appropriate means for optimising muscle mass adaptations without attenuating acute EI of older adults.
... In 2004, Carter et al. [4] were the first to investigate CHO mouth rinsing using a 6.4% CHO solution rinsed for 5 s every 12.5% of a cycling test and found a significant improvement in 1 h cycling time trial performance (+2.8%) in elite endurance cyclists. While mechanisms were not measured, the authors speculated that afferent signals from taste-receptor cells housed in papillae in the tongue and spread out over the soft palate and larynx may have altered perceived exertion leading to greater exercise performance. ...
... Chambers, Bridge and Jones [5] utilized functional magnetic resonance imaging to demonstrate that both glucose (with sweetness) and maltodextrin (no sweetness) in the mouth activates brain regions, including the anterior cingulate cortex and striatum, which are important for reward and motor control. Since the first investigation by Carter et al. [4], several studies have demonstrated that carbohydrate mouth rinsing (CMR) can improve aerobic endurance [6,7] and high-intensity exercise performances [8,9]. However, most of the literature focuses on aerobic-endurance based exercise or running and sprint type activities [6][7][8][9][10][11][12][13][14]; yet, evidence on muscular strength and endurance is limited. ...
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Carbohydrate (CHO) mouth rinse has been shown to enhance aerobic endurance performance. However, the effects of CHO mouth rinse on muscular strength and endurance are mixed and may be dependent on dosage of CHO. The primary purpose was to examine the effects of different dosages of CHO rinse on strength (bench press 1 repetition maximum [1-RM]) and muscular endurance (40% of 1-RM repetitions to failure) in female athletes. Sixteen resistance-trained females (age: 20 ± 1 years; height: 167 ± 3 cm; body mass: 67 ± 4 kg; BMI: 17 ± 2 kg/m 2 ; resistance training experience: 2 ± 1 years) completed four conditions in random order. The four conditions consisted of a mouth rinse with 25 mL solutions containing either 6% of CHO (Low dose of CHO: LCHO), 12% CHO (Moderate dose of CHO: MCHO), 18% CHO (High dose of CHO: HCHO) or water (Pla-cebo: PLA) for 10 s prior to a bench press strength and muscular endurance test. Maximal strength (1-RM), muscular endurance (reps and total volume), heart rate (HR), ratings of perceived exertion (RPE) and glucose (GLU) were recorded each condition. There were no significant differences in strength (p = 0.95) or muscular endurance (total repetitions: p = 0.06; total volume: p = 0.20) between conditions. Similarly, HR (p = 0.69), RPE (p = 0.09) and GLU (p = 0.92) did not differ between conditions. In conclusion, various doses of CHO mouth rinse (6%, 12% and 18%) have no effect on upper body muscular strength or muscular endurance in female athletes.
... Mouth swilling is an increasingly popular ergogenic strategy employed by athletes over short to moderate exercise durations [1][2][3][4][5][6], during nutrient restricted states [7][8][9][10] and may be appropriate during times of potential gastrointestinal distress [11,12]. Multiple nutritional stimuli are swilled, with each conferring a different ergogenic effect [5,6,13,14] and magnitude thereof, most likely due to affecting differing sensory pathways. ...
... Carbohydrate (CHO) is considered the gold-standard ergogenic mouth swilling strategy, with a wealth of literature documenting its efficacy in contrasting environments [21], nutritional states [22] and sports [23][24][25]. Mechanistically, CHO is shown to activate areas of the brain that are associated with behavioural, cognitive and emotional responses [3], with areas associated with motivation and motor control also stimulated [26]. Activation of these higher order and efferent regions of the brain, as supported by fMRI, provide strong explanation(s) for CHO mouth swilling's ergogenic effects to date, but CHO is also shown to affect receptors within the oral cavity [27], as are caffeine [28][29][30] and menthol [13,31,32]. ...
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Carbohydrate and menthol mouth-swilling have been used to enhance exercise performance in the heat. However, these strategies differ in mechanism and subjective experience. Participants (n=12) sat for 60 min in hot conditions (35°C; 15±2%), following a 15 min control period, participants undertook three 15 min testing blocks. A randomised swill (Carbohydrate; Menthol; Water) was administered per testing block (one swill every three minutes within each block). Heart rate, tympanic temperature, thermal comfort, thermal sensation and thirst were recorded every three minutes. Data were analysed by ANOVA, with carbohydrate intake controlled for via ANCOVA. Small elevations in heart rate were observed after carbohydrate (ES: 0.22 ± 90% CI: -0.09 to 0.52) and water swilling (0.26; -0.04 to 0.54). Menthol showed small improvements in thermal comfort relative to carbohydrate (-0.33; -0.63 to 0.03) and water (-0.40; -0.70 to -0.10), and induced moderate reductions in thermal sensation (-0.71; -1.01 to -0.40 and -0.66; -0.97 to -0.35, respectively). Menthol reduced thirst by a small to moderate extent. These effects persisted when controlling for dietary carbohydrate intake. Carbohydrate and water may elevate heart rate, whereas menthol elicits small improvements in thermal comfort, moderately improves thermal sensation and may mitigate thirst; these effects persist when dietary carbohydrate intake is controlled for.
... However, emerging evidence suggests that tasting certain substances, without ingestion, can influence exercise performance (for review, see: Best et al. 2021). This was first demonstrated by Carter et al. (2004) who showed that mouth rinsing a carbohydrate solution, and then expectorating, improved 1 h cycling time trial performance by 2.9%. However, the mechanisms via which carbohydrate mouth rinsing promotes ergogenic effects remain Communicated by Michalis G Nikolaidis. equivocal. ...
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Purpose To explore the effect of tasting unpleasant salty or bitter solutions on lower limb corticomotor excitability and neuromuscular function. Methods Nine females and eleven males participated (age: 27 ± 7 years, BMI: 25.3 ± 4.0 kg m ⁻² ). Unpleasant salty (1 M) and bitter (2 mM quinine) solutions were compared to water, sweetened water, and no solution, which functioned as control conditions. In a non-blinded randomized cross-over order, each solution was mouth rinsed (10 s) and ingested before perceptual responses, instantaneous heart rate (a marker of autonomic nervous system activation), quadricep corticomotor excitability (motor-evoked potential amplitude) and neuromuscular function during a maximal voluntary contraction (maximum voluntary force, resting twitch force, voluntary activation, 0–50 ms impulse, 0–100 impulse, 100–200 ms impulse) were measured. Results Hedonic value (water: 47 ± 8%, sweet: 23 ± 17%, salt: 71 ± 8%, bitter: 80 ± 10%), taste intensity, unpleasantness and increases in heart rate (no solution: 14 ± 5 bpm, water: 18 ± 5 bpm, sweet: 20 ± 5 bpm, salt: 24 ± 7 bpm, bitter: 23 ± 6 bpm) were significantly higher in the salty and bitter conditions compared to control conditions. Nausea was low in all conditions (< 15%) but was significantly higher in salty and bitter conditions compared to water (water: 3 ± 5%, sweet: 6 ± 13%, salt: 7 ± 9%, bitter: 14 ± 16%). There was no significant difference between conditions in neuromuscular function or corticomotor excitability variables. Conclusion At rest, unpleasant tastes appear to have no influence on quadricep corticomotor excitability or neuromuscular function. These data question the mechanisms via which unpleasant tastes are proposed to influence exercise performance.
... Although speculative, the lack of significant benefits on physical performance in this study could be due to the fact that the sensing of carbohydrates and menthol in the mouth affects similar nervous signaling pathways and, hence, the erogenicity of both substances is not additive. In fact, carbohydrate mouth rinsing is known to be ergogenic on its own, without supplying additional energy to the body (148). Therefore, more significant results are found with the administration of menthol, in comparison with no-beverage or beverages that do not exert an ergogenic role. ...
Article
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Exercise in a hot and humid environment may endanger athlete’s health and affect physical performance. This systematic review aimed to examine whether internal administration of ice, cold beverages or menthol solutions may be beneficial for physical performance when exercising in different environmental conditions and sports backgrounds. A systematic search was performed in PubMed, Web of Science, Scopus and SPORTDiscus databases, from inception to April 2022, to identify studies meeting the following inclusion criteria: healthy male and female physically active individuals or athletes (aged ≥18 years); an intervention consisting in the internal administration (i.e., ingestion or mouth rinse) of ice slush, ice slurry or crushed ice and/or cold beverages and/or menthol solutions before and/or during exercise; a randomized crossover design with a control or placebo condition; the report of at least one physical performance outcome; and to be written in English. Our search retrieved 2,714 articles in total; after selection, 43 studies were considered, including 472 participants, 408 men and 64 women, aged 18-42 years, with a VO 2max ranging from 46.2 to 67.2 mL⋅kg –1 ⋅min –1 . Average ambient temperature and relative humidity during the exercise tasks were 32.4 ± 3.5°C (ranging from 22°C to 38°C) and 50.8 ± 13.4% (varying from 20.0% to 80.0%), respectively. Across the 43 studies, 7 exclusively included a menthol solution mouth rinse, 30 exclusively involved ice slurry/ice slush/crushed ice/cold beverages intake, and 6 examined both the effect of thermal and non-thermal internal techniques in the same protocol. Rinsing a menthol solution (0.01%) improved physical performance during continuous endurance exercise in the heat. Conversely, the ingestion of ice or cold beverages did not seem to consistently increase performance, being more likely to improve performance in continuous endurance trials, especially when consumed during exercises. Co-administration of menthol with or within ice beverages seems to exert a synergistic effect by improving physical performance. Even in environmental conditions that are not extreme, internal cooling strategies may have an ergogenic effect. Further studies exploring both intermittent and outdoor exercise protocols, involving elite male and female athletes and performed under not extreme environmental conditions are warranted. Systematic review registration: [ https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021268197 ], identifier [CRD42021268197].
... There are currently two proposed mechanisms of carbohydrate ergogenicity. Firstly, carbohydrates can be sensed in the oral cavity, causing an activation of certain brain regions, leading to stimulation of the central nervous system, as shown by improved performance by carbohydrate mouth rinsing [49][50][51]. Secondly, and most importantly, carbohydrates provide an additional fuel source for ATP formation during exercise. ...
Article
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The importance of carbohydrate as a fuel source for exercise and athletic performance is well established. Equally well developed are dietary carbohydrate intake guidelines for endurance athletes seeking to optimize their performance. This narrative review provides a contemporary perspective on research into the role of, and application of, carbohydrate in the diet of endurance athletes. The review discusses how recommendations could become increasingly refined and what future research would further our understanding of how to optimize dietary carbohydrate intake to positively impact endurance performance. High carbohydrate availability for prolonged intense exercise and competition performance remains a priority. Recent advances have been made on the recommended type and quantity of carbohydrates to be ingested before, during and after intense exercise bouts. Whilst reducing carbohydrate availability around selected exercise bouts to augment metabolic adaptations to training is now widely recommended, a contemporary view of the so-called train-low approach based on the totality of the current evidence suggests limited utility for enhancing performance benefits from training. Nonetheless, such studies have focused importance on periodizing carbohydrate intake based on, among other factors, the goal and demand of training or competition. This calls for a much more personalized approach to carbohydrate recommendations that could be further supported through future research and technological innovation (e.g., continuous glucose monitoring). Despite more than a century of investigations into carbohydrate nutrition, exercise metabolism and endurance performance, there are numerous new important discoveries, both from an applied and mechanistic perspective, on the horizon.
... Their hypothesis based on that the salty (NaCl) mouth rinse solution, which is frequently used in dentistry to desensitize the oral cavity to pain, may influence the insular cortex and/or opioid receptor activities by activating the 'salty' taste receptors in the oral cavity, which in turn affects the parasympathetic nervous system, which regulates cardiac automatic activity that it can potentially cause changes in the brain and protect the maximum voluntary contraction performance. In addition, it was suggested that since CHO-MR had no effect on metabolic processes in the study (Carter et al., 2004), alterations in central drive (executive) or motivation level may contribute to reported enhancements in performance. For this reason, it has been claimed that it is appropriate to examine the effect of mouth rinsing on exercises involving high central drive, such as maximum voluntary contraction. ...
Article
Aim: The purpose of this research is to examine the effects of oral rinsing of CHO and NaCl on repeated sprint performance in trained athletes. Methods: Fifteen trained athletes (5 women; 10 men) voluntarily participated in the repeated, single-blind, placebo-controlled and crossover design study. Athletes came to the laboratory with a night fasting four times with an interval of at least 48 hours and participated in the repeated sprint test (10 sec × 6, 40 sec intervals) after 30 minutes of endurance exercise (70% maxVO2). At the 0th, 10th, 20th and 30th minutes of the endurance exercise, it was requested to MR with CHO (6.4% maltodextrin), sodium chloride (6.4%) solution and water (placebo) or no rinsing (control). Results: As a result of the analyzes performed with 3 × 4 ANOVA, the power output variables obtained by repeated sprint performance [peak power, average power, minimum power (W, W/kg) and fatigue index (%)] and fatigue variables (heart rate, blood lactate level and rate of perceived exertion) between sessions were not found to be significantly different. Conclusion From the obtained results, it may be concluded that the method and stimuli used in this study seem insufficient to affect the outcome variables of physical performance.
... The effect of CHO mouth rinse on brain activity seems to be independent of sweetness of the CHO solution (Chambers, Bridge, and Jones 2009). It is well-accepted that CHO mouth rinsing improves performance during endurance exercise lasting from 30 to 75 minutes (Carter, Jeukendrup, and Jones 2004;Pottier et al. 2010;Sinclair et al. 2014;Jeukendrup 2014;De Ataide e Silva et al. 2013;Brietzke et al. 2019). Nevertheless, the effects of CHO mouth rinse on muscle strength and muscular endurance are less clear and underexplored. ...
Article
The present systematic review with meta-analysis summarized studies that investigated the effect of carbohydrate (CHO) mouth rinse on muscle strength and muscular endurance. The search was performed in six databases. Thirteen randomized clinical trials were selected and the standardized mean difference between CHO mouth rinse and placebo for maximal strength and muscular endurance was determined via a random-effects model using Review Manager 5.4 software. Meta-regression was also performed to explore the influence of load, number of sets, number of exercises, fasting time, CHO concentration, and number of mouth rinses on the main outcomes. There was no significant effect of CHO mouth rinse on maximal strength (mean difference= 0.25 kg, 95%CI - 1.81 to 2.32 kg, z = 0.24, p = 0.810). However, there was a significant positive effect of CHO mouth rinse on muscular endurance (mean difference = 1.24 repetitions, 95%CI 0.70 to 1.77 repetitions, z = 4.55, p < 0.001). Meta-regression identified that CHO mouth rinse has greater benefits on muscular endurance when using high workloads, multiple exercises, and a smaller number of mouth rinses (p = 0.001). In conclusion, CHO mouth rinse has no effect on maximal muscle strength but has a positive effect on muscular endurance and seems to optimize when fewer mouth rinses, high workloads and numbers of exercises are used.
... Ingested CHOs are metabolized via pathways that preserve muscle glycogen and maintain blood glucose levels [1]. Recently, CHO mouth rinses, which do not involve ingesting the CHO, have been introduced to maintain performance during exercises lasting for 30-75 min or during high-intensity exercise when there is no significant reduction in blood glucose levels [2][3][4][5]. ...
Article
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Mouth rinsing with a carbohydrate (CHO) solution has emerged as a sports nutrition strategy to increase endurance performance. This study aimed to clarify the effects of two forms of CHO sensing in the mouth (i.e., CHO mouth rinse (CMR) and CHO mouth spray (CMS)) on exercise performance during prolonged exercise, including ultra-high intensity intermittent exercise over time. We conducted the following experimental trials: (1) 6% glucose solution (G), (2) 6% CMR, (3) 6% CMS, and (4) water (WAT). These trials were conducted at least 1 week apart in a randomized crossover design. Eight male college students performed constant-load exercise for 60 min (intensity 40% VO2peak), four sets of the Wingate test (three 30 s Wingate tests with a 4 min recovery between each test), and a constant-load exercise for 30 min (intensity 40% VO2peak). The mean exercise power output (Watt), ratings of perceived exertion, and blood glucose levels were measured. We found that the mean power values of the CMR and CMS in the third and fourth sets was significantly higher than that of WAT (p < 0.05), and that the G trial did not show a significant difference from any other trial. Thus, when compared to G or WAT, CMR and CMS can help improve endurance exercise performance.
... The important conclusion must be that glucose ingestion or infusion does not enhance exercise performance [14,27,49,51,[57][58][59][69][70][71][72][73] by slowing muscle glycogen use, which in turn means that carbohydrate ingestion during exercise most likely influences exercise performance by a central brain mechanism: either by maintaining central motor drive by protecting against hypoglycemia, or by as yet to be determined reflex central brain mechanism [74][75][76]. ...
Article
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The introduction of the needle muscle biopsy technique in the 1960s allowed muscle tissue to be sampled from exercising humans for the first time. The finding that muscle glycogen content reached low levels at exhaustion suggested that the metabolic cause of fatigue during prolonged exercise had been discovered. A special pre-exercise diet that maximized pre-exercise muscle glycogen storage also increased time to fatigue during prolonged exercise. The logical conclusion was that the athlete’s pre-exercise muscle glycogen content is the single most important acutely modifiable determinant of endurance capacity. Muscle biochemists proposed that skeletal muscle has an obligatory dependence on high rates of muscle glycogen/carbohydrate oxidation, especially during high intensity or prolonged exercise. Without this obligatory carbohydrate oxidation from muscle glycogen, optimum muscle metabolism cannot be sustained; fatigue develops and exercise performance is impaired. As plausible as this explanation may appear, it has never been proven. Here, I propose an alternate explanation. All the original studies overlooked one crucial finding, specifically that not only were muscle glycogen concentrations low at exhaustion in all trials, but hypoglycemia was also always present. Here, I provide the historical and modern evidence showing that the blood glucose concentration—reflecting the liver glycogen rather than the muscle glycogen content—is the homeostatically-regulated (protected) variable that drives the metabolic response to prolonged exercise. If this is so, nutritional interventions that enhance exercise performance, especially during prolonged exercise, will be those that assist the body in its efforts to maintain the blood glucose concentration within the normal range.
... Although indicators like heart rate variability, blood pressure and respiratory rate were studied in the context of mental fatigue (Richter et al., 2008;Hsu et al., 2015), it seems to be based on mechanisms that are rather separate from those that physical fatigue is usually characterized by, which originate in skeletal muscle activity (Dantzer et al., 2014;Abd-Elfattah et al., 2015). Moreover, the effects for theta and alpha band activity may not be as significant as shown in some previous studies, which corroborates the notion, as well as previous evidence, that pinpointing a physiological marker of mental fatigue is difficult (Dantzer et al., 2014;Abd-Elfattah et al., 2015;Brietzke et al., 2021) (also see the discussion on the role of glucose in effortful self-control as well as related research in the psychology of sports and performance: Carter et al., 2004;Chambers et al., 2009;Beedie and Lane, 2012;Molden et al., 2012;Sanders et al., 2012;Carter and McCullough, 2013;Hagger and Chatzisarantis, 2013;Finley et al., 2019). Due to this, subjective declarations of increased fatigue and tiredness as well as decreases in performance effectiveness are the main indicators of mental fatigue in previous research. ...
... Many studies have observed a lower RPE with carbohydrate supplementation compared to a placebo (Coggan & Coyle, 1987;Kang et al., 1996;Robertson et al., 1990;Utter et al., 2002;Utter et al., 2004). This reduced RPE can be partially explained by a greater carbohydrate oxidation rate in the carbohydrate supplementation group (Robertson et al., 1990;Utter et al., 2004) and by the effect of carbohydrate supplementation on the central nervous system (Beelen et al., 2009;Carter et al., 2004;Chambers et al., 2009). ...
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This study aimed to determine the effects of consuming a high fat solution (HFS) compared to a high carbohydrate solution (HCS) during a cycling effort on substrate oxidation, muscle oxygenation and performance with cyclists and triathletes. Thirteen men participated in this study (age: 30.4 ± 6.3 y; height: 178.7 ± 6.1 cm; weight: 74.9 ± 6.5 kg; V̇O2 peak: 60.5 ± 7.9 mlO2×kg-1×min-1). The solutions were isocaloric (total of 720 kcal) and were consumed every 20 minutes. Each solution of HFS contained 12.78 g of lipids, 1.33 g of carbohydrates and 0.67 g of proteins, and each solution of HCS contained 28 g of carbohydrates. We measured pulmonary oxygen consumption and skeletal muscle oxygenation, using a Near Infrared Spectrometer (NIRS) during a cycling effort consisting of 2 hours at 65 % of maximal aerobic power (MAP) followed immediately by a 3-minute time-trial (TT). We observed that the consumption of the HFS increased the rate of fat oxidation at the end of the sub-maximal effort (0.61 ± 0.14 vs 0.53 ± 0.17 g×min-1, p < 0.05). We have also shown that the HFS negatively affected the performance in the TT (mean Watts: HCS: 347.0 ± 77.4 vs HFS: 326.5 ± 88.8 W; p < 0.05) and the rating of perceived exertions during the sub-maximal effort (modified Borg Perceived Exertion scale: 1–10) (mean: 3.62 ± 0.58 for HCS vs 4.16 ± 0.62 for HFS; p < 0.05). We did not observe a significant effect of the acute consumption of the HFS compared to the HCS on muscle oxygenation during the cycling effort. Finally, we observed that cyclists who demonstrated a high skeletal muscle deoxygenation relative to their pulmonary oxygen consumption (DHHb/V̇O2) had a higher fat oxidation capacity (higher Fatmax). In conclusion, even though the consumption of HFS increased the rate of fat oxidation at the end of a sub-maximal effort, it did not affect muscle oxygenation and it negatively affected performance and perceived exertion during a time-trial and caused gastro-intestinal distress in some participants. Keywords: Fat oxidation, Skeletal muscle oxygenation, Lipid supplementation, Carbohydrate supplementation, Near Infrared Spectroscopy (NIRS), Cycling, Triathlon.
... Time to pVGRF during lower-extremity muscle fatigue and trunk flexion angle during brain fatigue, which were altered during the 10-min task and prior to reaching maximal fatigue, may be more pronounced during such actual sports activities. Simply rinsing out the mouth with a sugar solution as a preventive measure against central fatigue has been shown to improve performance 27 ) . The results of this study indicate that the landing motion may be altered during fatigue compared to resting, which may provide important basic information for studying preventive measures. ...
Article
Objective: Anterior cruciate ligament (ACL) injury is one of the most frequent sportsinjuries, and previous studies have shown that fatigue is a risk factor for sports injuries.This study aimed to inform prevention of ACL injury by investigating how exercise and desk tasks affect trunk and lower limb alignment and ground reaction force (GRF) during one-legged landing movements. Methods: The study subjects were 12 men who performed a one-legged landing movement from a 30-cm platform before and after fatigue tasks, including lower-limb muscle fatigue, cardiopulmonary fatigue, and brain fatigue tasks. For the measurement of joint angles and moments and GRF, a three-dimensional motion analysis device and a floor reaction-force meter were used. Statistics were performed using Wilcoxon's signed rank sum test as a multiple comparison test with Bonferroni adjustment to compare the difference in effects. Results: The maximum trunk flexion angle during landing on one leg was significantly lower in the brain fatigue group than in the control group. The time to peak vertical GRF (pGRF) was significantly shorter in the leg-muscle fatigue group than in the control group. Conclusion: Brain fatigue may have altered the postural strategy before and after landing, resulting in a decrease in trunk flexion angle. Time to pVGRF was shortened in the leg muscle fatigue group, suggesting that there may be an increased risk of ACL injury. Time to pVGRF during lower extremity muscle fatigue and trunk flexion angle during brain fatigue may be more pronounced during actual sports activities.
... A CNS-mediated response to oral exposure of macromolecules, including carbohydrates, has been demonstrated (Jeukendrup 2013). For example, a carbohydrate oral "swish" without ingestion increases blood glucose and enhances athletic performance (Carter 2004, Rollo 2008). This effect has been linked to CNS activation of metabolic pathways that occurs pre-ingestion (Chambers 2009). ...
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Background Serotonin syntheses in the brain requires a steady supply of tryptophan. Branched chain amino acids (BCAA) and tryptophan are transported across the blood-brain barrier by the amino acid transporter LAT1. BCAA supplementation is predicted to decrease serotonin biosynthesis through LAT1 competition and reduce central fatigue during exercise. Despite a strong theoretical basis for BCAA to attenuate serotonin production and fatigue during exercise, a number of human clinical trials have failed to demonstrate these benefits. To shed light on this discrepancy, we measured the impact of BCAA supplementation on serotonin and associated metabolites during exercise. Methods A cohort of endurance runners (n=10) participated in a randomized, placebo-controlled, crossover trial to determine impact of BCAA supplementation during a 60-minute run at 65% of VO2 max. Metabolomic analysis targeted for serotonin and untargeted analysis for biomarkers of BCAA supplementation using LCMS were performed on serum samples collected immediately before and after exercise. Results Serum BCAA levels were greater in the supplement group compared to placebo (p<0.05). Serum serotonin was lower immediately after BCAA supplementation and before exercise (p<0.05) but not after exercise. L-ornithine increased during exercise with BCAA treatment compared to placebo. Ratings of perceived exertion were no different in BCAA and placebo groups. Conclusions BCAA supplementation led to a rapid decrease in serum serotonin concentration relative to placebo, which may be indicative of a central nervous system (CNS) mediated process. After exercise with BCAA supplementation, endurance athletes did not show lower serum serotonin concentration, but did present an almost three-fold increase in L-ornithine which has metabolic connections to cortisol and central fatigue. Trial Registration: ClinicalTrials.gov NCT04969536, retrospectively registered 20 July 2021, https://clinicaltrials.gov/ct2/show/NCT04969536
... Previous research has demonstrated that the use of a CHO MR before or during exercise may have potential ergogenic effects in a variety of athletic populations. In cyclists, CHO MR has been shown to improve power output and/or performance time during time trials of varying distances (Baltazar-Martins and Del Coso 2019; Bavaresco Gambassi et al. 2019;Carter et al. 2004;Chambers et al. 2009;Jensen et al. 2018;Murray et al. 2018). In distance runners, rinsing or ingestion of a CHO solution has been shown to increase time to exhaustion during treadmill running (Fraga et al. 2017;Kamaruddin et al. 2019). ...
Article
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PurposeCarbohydrate (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.ResultCHO 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).ConclusionA 6.4% maltodextrin CHO MR did not alter total distance walked, perceived exertion, or other physiological responses elicited by the 6MWT in older adults.
... As caffeine mouth rinse effects are probably mediated by activation of reward and pleasure circuitry impacting perception of effort (Carter, Jeukendrup, and Jones 2004), a non-improvement during high-intensity exercise after caffeine mouth rinse may be due to this mode of exercise already be performed near-maximal perception of effort. This characteristic decreases the possibility of improving in physical performance via reduction of effort perception (i.e., ceiling effect). ...
Article
Caffeine is one of the most used ergogenic aids for improving athletic and cognitive performance. However, the use of alternative forms of caffeine administration has recently been proposed as a form to mitigate possible side effects. We therefore conducted a systematic review of the studies examining the effects of caffeine mouth rinsing on physical and cognitive performance. Using the PRISMA guidelines, we identified 1791 studies on four electronics databases (Cochrane, Pubmed, Science Direct and Web of Science). From these, 18 articles fulfilled the inclusion criteria (15 for physical performance and 3 for cognitive performance). The results from the PEDro scale indicate that, in general, studies with good methodological quality have been included in the present review (8.3 ± 1.7 for physical performance and 8 ± 1.7 for cognitive performance). All selected studies found an improvement in cognitive performance with caffeine mouth rinse. Five studies found positive effects of caffeine mouthwash on physical performance when repeated mouthwash was performed during exercise, while one study detected a positive effect of caffeine mouth rinse with a single mouthwash before exercise, but only in a fasted state. Among these studies that showed positive effects, however, three (2 for physical performance and 1 for cognitive performance) presented fair methodological quality. There was also a variety of methodological approach in the studies that showed no improvement in physical performance with caffeine mouth rinse, which may have influenced the potential to detect the ergogenic effect of caffeine mouth rinse. Thus, the effects of caffeine mouth rinse on physical performance are mixed, but a potential ergogenic effect might be present in a fasted state and when mouthwash is repeated during exercise. Concerning cognitive performance, caffeine mouth rinse seems to be a beneficial strategy.
... However, this is speculative as the effect of pre-exercise CHO on anaerobic performance was not assessed in the current study. Other factors at play could be beneficial effects of CHO on the central nervous system, by delaying central fatigue (Carter et al., 2004;Clark et al., 2019). Lastly, other effects of CHO solely related to delaying fatigue by attenuating the accumulation of ATP breakdown products without interacting with the performance-determining variables (Costill and Hargreaves, 1992;Clark et al., 2019). ...
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The current study aimed to investigate the effect of the relative CHO content in a pre-event meal on time to exhaustion (TTE), peak oxygen uptake ( V ∙ O 2 peak ), the 2nd lactate threshold (LT2), onset of blood lactate accumulation (OBLA), and work economy (WE) and to compare responses between well-trained and recreationally trained individuals. Eleven well-trained and 10 recreationally trained men performed three trials in a randomized cross-over design, in which they performed exercise tests (1) after a high-CHO pre-event meal (3 g · kg-1), (2) a low-CHO pre-event meal (0.5 g · kg-1), or (3) in a fasted-state. The test protocol consisted of five submaximal 5-min constant-velocity bouts of increasing intensity and a graded exercise test (GXT) to measure TTE. A repeated measure ANOVA with a between-subjects factor (well-trained vs. recreational) was performed. A main effect of pre-event meal was found (p = 0.001), with TTE being 8.0% longer following the high-CHO meal compared to the fasted state (p = 0.009) and 7.2% longer compared to the low-CHO meal (p = 0.010). No significant effect of pre-event meal on V ∙ O 2 peak , LT2, OBLA, or WE (p ≥ 0.087) was found and no significant interaction effect between training status and pre-event CHO intake was found for TTE or any of the performance-determining variables (p ≥ 0.257). In conclusion, high-CHO content in the pre-event meal led to a longer TTE compared to a meal with a low-CHO content or exercising in a fasted state, both in well-trained and recreationally trained participants. However, the underlying physiological reason for the increased TTE is unclear, as no effect of pre-event meal on the main physiological performance-determining variables was found. Thus, pre-event CHO intake should be standardized when the goal is to assess endurance performance but seems to be of less importance when assessing the main performance-determining variables.
... , maintenance of plasma glucose and elevated CHO oxidation rates (Coyle, Coggan, Hemmert, & Ivy, 1986) and direct effects upon the central nervous system (CNS) (Carter, Jeukendrup, & Jones, 2004). Contemporary guidelines for athletic populations (Thomas et al., 2016) currently recommend CHO mouth rinsing when exercise duration is <60 min, CHO intake at a rate of 30-60 g·h −1 (from single sources such as glucose or maltodextrin) during 1-2.5 h of endurance exercise and finally, up to 90 g·h −1 of multi-transportable CHO (glucose:fructose blends) when exercise duration is >2.5 h. ...
Article
Optimal carbohydrate and protein intakes are vital for modulating training adaptation, recovery, and exercise performance. However, the research base underpinning contemporary sport nutrition guidelines has largely been conducted in male populations with a lack of consensus on whether the menstrual phase and associated changes in sex hormones allow broad application of these principles to female athletes. The present review will summarise our current understanding of carbohydrate and protein requirements in female athletes across the menstrual cycle and provide a critical analysis on how they compare to male athletes. On the basis of current evidence, we consider it premature to conclude that female athletes require sex specific guidelines in relation to CHO or protein requirements provided energy needs are met. However, there is a need for further research using sport-specific competition and training related exercise protocols that rigorously control for prior exercise, CHO/energy intake, contraceptive use and phase of menstrual cycle. Our overarching recommendation is to use current recommendations as a basis for adopting an individualised approach that takes into account athlete specific training and competition goals whilst also considering personal symptoms associated with the menstrual cycle.
... The glucose solution presence in the mouth can impact on improved physical and cognitive performance [110,111] (Table 4). A 3% increase in performance was observed by following the rinsing of a maltodextrin solution around in the mouth before and during exercise [112] (Table 4). Most studies that found a positive effect were carried out in the fasted state. ...
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Proper nutrition is a key factor in physical performance, but there are also indications of an impact of dietary components on the brain function. Therefore, the aim of the study was to assess the impact of macronutrients and water on cognitive performance. Assumptions of the Mediterranean diet correlate with better global cognition, episodic memory, lower risk of cognitive impairment and neurodegenerative diseases. In turn, a high-fat and high-sugar diet shows the opposite effect. Omega-3 fatty acids could be used as a preventive tool for cognitive decline, but there is still insufficient evidence if supplementation improves cognitive functions. The proper intake of protein may be important in cognitive performance. Tyrosine seems to be potentially effective in inhibition of fatigue under extreme conditions, and the influence of BCAA on cognitive performance is still unclear. An appropriate glucose level is a critical factor for brain functions. Carbohydrate supplementation before and during exercise is associated with enhanced brain activation and decreased exercise perception, as well as improved cognitive functions. Dehydration worsens cognitive performance, especially for tasks requiring attention, executive functions and coordination. Based on the review of available studies, it should be assumed that proper nutrition might play a relevant role in athletes' cognitive performance.
... In this way, CAF mouth rinse may overcome the effect of hepatic metabolism (clearance). CAF mouth rinse is one of the alternative forms of administration that has gained interest alongside carbohydrate mouthwash studies [7,9]; however, the improvements in performance have been demonstrated in shortterm resistance exercises (less than 1 h) [7,9e11]. CAF mouth rinse has been tested in different sports modalities, such as in cycling sprints [12,13], 30 min of cycling [14], on intermittent running [15]. ...
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Purpose This study assessed whether caffeine mouth rinsing affects 10-km run performance and vertical jump in recreational runners. Methods A double-blind, placebo-controlled, crossover study was conducted. Ten well-trained volunteers performed two trials, following caffeine or placebo mouth rinse, separated by seven days. Immediately before the 10-km run, a 10-second mouth rinse with either 300 mg of caffeine (1.2%) or microcrystalline cellulose (placebo) diluted in 25 mL of water was performed. Pre- and post-exercise, participants performed a vertical jump test. A Garmin Forerunner® GPS, was used to measure 10-km running time and an 11-point Borg scale was used post-exercise to measure ratings of perceived exertion. Blood samples were also collected during the visit in the laboratory in the afternoon period to classify individuals according to their CYP1A2 genotype. Vertical jump performance was evaluated using a force plate. Results Nine runners (90%) were CC homozygotes and one (10%) was an AC heterozygote for CYP1A2. There was no difference in 10-km time-trial performance (Placebo: 47.07±5.18 vs. CAF: 47.45±6.34 min, p = 0.89), ratings of perceived exertion (Placebo: 17±1 vs. CAF: 16±2, p = 0.34) or vertical jump power (Placebo, Pre: 4.5±0.6 W•kg-1 and Post: 4.5±0.7 W•kg-1; CAF: Pre: 4.4±0.7 W•kg-1 and Post: 4.4±0.8 W•kg-1, d = 0.21, p = 0.66) between trials. Conclusion Acute caffeine mouth rinsing (1.2%) did not improve 10-km performance and showed similar null effects on vertical jump performance in CYP1A2 C-allele carriers.
... These improvements could be due to a Communicated by Michael Lindinger. number of factors such as stimulation of CHO receptors in the oral cavity and thereby modulating neural drive and attenuating perceived exertion (Carter et al. 2004), and/or maintenance of plasma glucose concentration leading to an increase in CHO oxidation late in exercise (Coggan and Coyle 1989;Jeukendrup 2004). In addition, CHO intake during exercise not only increases oxidation but may spare the use of the limited muscle glycogen and thereby improve performance or capacity (Stellingwerff et al. 2007;Tsintzas et al. 1995), although not universally accepted as a number of studies have failed to show a sparing effect on muscle glycogen (Coyle et al. 1986;Mitchell et al. 1989). ...
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Purpose Carbohydrates (CHO) are one of the fundamental energy sources during prolonged steady state and intermittent exercise. The consumption of exogenous CHO during exercise is common place, with the aim to enhance sporting performance. Despite the popularity around exogenous CHO use, the process by which CHO is regulated from intake to its use in the working muscle is still not fully appreciated. Recent studies utilizing the hyperglycaemic glucose clamp technique have shed light on some of the potential barriers to CHO utilisation during exercise. The present review addresses the role of exogenous CHO utilisation during exercise, with a focus on potential mechanisms involved, from glucose uptake to glucose delivery and oxidation at the different stages of regulation. Methods Narrative review. Results A number of potential barriers were identified, including gastric emptying, intestinal absorption, blood flow (splanchnic and muscle), muscle uptake and oxidation. The relocation of glucose transporters plays a key role in the regulation of CHO, particularly in epithelial cells and subsequent transport into the blood. Limitations are also apparent when CHO is infused, particularly with regards to blood flow and uptake within the muscle. Conclusion We highlight a number of potential barriers involved with the regulation of both ingested and infused CHO during exercise. Future work on the influence of longitudinal training within the regulation processes (such as the gut) is warranted to further understand the optimal type, dose and method of CHO delivery to enhance sporting performance.
... Mechanistically, the effects of CHO on performance can be partially attributed to influences on the central nervous system, and related effects on perceived effort, affect, and reduced inhibition of central motor drive . This is best illustrated by numerous studies reporting that mouth rinsing with CHO (without swallowing) can significantly improve TT performance (Carter et al. 2004;Chambers et al. 2009). These central influences are likely the primary mechanism responsible for ergogenic effects of CHO during shorter endurance events (~ 45 to 75 min). ...
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Purpose To critically examine the research on novel supplements and strategies designed to enhance carbohydrate delivery and/or availability. Methods Narrative review. Results Available data would suggest that there are varying levels of effectiveness based on the supplement/supplementation strategy in question and mechanism of action. Novel carbohydrate supplements including multiple transportable carbohydrate (MTC), modified carbohydrate (MC), and hydrogels (HGEL) have been generally effective at modifying gastric emptying and/or intestinal absorption. Moreover, these effects often correlate with altered fuel utilization patterns and/or glycogen storage. Nevertheless, performance effects differ widely based on supplement and study design. MTC consistently enhances performance, but the magnitude of the effect is yet to be fully elucidated. MC and HGEL seem unlikely to be beneficial when compared to supplementation strategies that align with current sport nutrition recommendations. Combining carbohydrate with other ergogenic substances may, in some cases, result in additive or synergistic effects on metabolism and/or performance; however, data are often lacking and results vary based on the quantity, timing, and inter-individual responses to different treatments. Altering dietary carbohydrate intake likely influences absorption, oxidation, and and/or storage of acutely ingested carbohydrate, but how this affects the ergogenicity of carbohydrate is still mostly unknown. Conclusions In conclusion, novel carbohydrate supplements and strategies alter carbohydrate delivery through various mechanisms. However, more research is needed to determine if/when interventions are ergogenic based on different contexts, populations, and applications.
... A 6.4% maltodextrin solution rinsed around the mouth for 5 seconds enhanced 1-hour time trial performance. 11 Further, a meta-analysis analyzing 16 trials shows that a carbohydrate mouth rinse improves mean power output. 12,13 Therefore, enhanced performance previously observed 8 could be due to the mouth rinse effect. ...
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Trehalose is a disaccharide consisting of 2 glucose units linked in an alpha 1,1-glycosidic bond. Pre-exercise trehalose ingestion enhances exercise performance within 30 minutes. Enhanced performance was hypothesized to be due to a mouth rinse effect. A 3-arm double-blind crossover trial was conducted to test this hypothesis. Ten healthy male collegiate distance runners rinsed their mouths with either trehalose (6% w/v) or maltose (6% w/v) or acesulfame potassium (0.04 mg/mL) for 5 seconds and then performed an exercise assessment composed of 6-second peak power and endurance tests. Trehalose induced the highest mean power output ( P < .01) in peak power tests. In the endurance test, trehalose consistently showed higher mean power output than maltose. The 3 test drinks displayed indistinguishable sweetness and were expected to activate receptors for sweetness (T1R2-T1R3) with the same intensity. Trehalose activates taste receptors T1R1-T1R3, T1R3-T1R3 homodimer, and T1R2-T1R3, whereas sucrose activates only T1R2-T1R3. Therefore, a difference in mouth rinse effect might be due to a specific receptor in the oral cavity that recognizes differences between trehalose and maltose.
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Günümüzde, ülkemizde ve dünyada farklı isimler altında “spor içeceği” ve “enerji içeceği” pazarlanmaktadır. Çoğunlukla, bu iki içecek birbiriyle karıştırılmakta, hatta başta çocuklar olmak üzere birçok kişi bundan olumsuz etkilenmektedir. Özellikle, bu içeceklerin çocuklar ve yetişkinler arasında kullanımı istismara açık bir durum yaratmakta, bazen bu konuda yeterince bilgi sahibi olmayan ebeveynler tarafından da teşvik edilebilmektedir. Diğer yandan, spor camiasında da bu konuda açıklık yoktur. Hangi içeceğin, gerçekten faydalı olacağı sadece ürünü pazarlayan kişilerin bilgisine bırakılmıştır. Doğru ürünün seçildiği durumlarda bile, hangi egzersiz yoğunluğu ve süresi boyunca nasıl bir kullanım yapılacağına dair bilgiler son derece kısıtlıdır. Son yıllarda, dünya ve ülkemiz genelinde doğal ürünlere olan ilgi artmış olsa da, bu ürünlerdeki yararlı doz nedir ? sorusu akla gelmektedir. Bir diğer soru da, bu içecekler gerçekten faydalı mı ? Ya da hangileri, ne düzeyde faydalı ? Bu derleme çalışmada, spor içeceklerinin kısa tarihinden başlayarak, bu içeceklerin özellikleri ve yapılarını karşılaştırarak doğru ürün seçimi üzerine bilimsel çerçeveden katkı sağlamak amaçlanmıştır.
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Previous systematic reviews have confirmed that carbohydrate (CHO) mouth rinse may boost physical exercise performance, despite some methodological aspects likely affecting its ergogenic effect. In this review, we discussed if the exercise mode, pre-exercise fasting status, CHO solutions concentration, CHO solutions temperature, mouth rinse duration, and CHO placebo effects may potentially reduce the CHO mouth rinse ergogenic effect, suggesting possible solutions to manage these potential confounders. The effectiveness of CHO mouth rinse as a performance booster is apparently related to the origin of the exercise-induced neuromuscular fatigue, as CHO mouth rinse unequivocally potentiates endurance rather than sprint and strength exercises performance. Furthermore, ergogenic effects have been greater in fasting than fed state, somehow explaining the varied magnitude of the CHO mouth rinse effects in exercise performance. In this regard, the CHO solution concentration and temperature, as well as the mouth rinse duration, may have increased the variability observed in CHO mouth rinse effects in fasting and fed state. Finally, placebo effects have challenged the potential of the CHO mouth rinse as an ergogenic aid. Therefore, we suggest that future studies should consider methodological controls such as sample size and sample homogeneity, proper familiarization with experimental procedures, and the use of alternative placebo designs to provide unbiased evidence regarding the potential of the CHO mouth rinse as an ergogenic aid
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Ketone ingestion can alter metabolism but effects on exercise performance are unclear, particularly with regard to the impact on intermittent-intensity exercise and team-sport performance. Nine professional male rugby union players each completed two trials in a double-blind, randomized, crossover design. Participants ingested either 90 ± 9 g carbohydrate (CHO; 9% solution) or an energy matched solution containing 20 ± 2 g CHO (3% solution) and 590 mg/kg body mass β-hydroxybutyrate monoester (CHO + BHB-ME) before and during a simulated rugby union-specific match-play protocol, including repeated high-intensity, sprint and power-based performance tests. Mean time to complete the sustained high-intensity performance tests was reduced by 0.33 ± 0.41 s (2.1%) with CHO + BHB-ME (15.53 ± 0.52 s) compared with CHO (15.86 ± 0.80 s) placebo ( p = .04). Mean time to complete the sprint and power-based performance tests were not different between trials. CHO + BHB-ME resulted in blood BHB concentrations that remained >2 mmol/L during exercise ( p < .001). Serum lactate and glycerol concentrations were lower after CHO + BHB-ME than CHO ( p < .05). Coingestion of a BHB-ME with CHO can alter fuel metabolism (attenuate circulating lactate and glycerol concentrations) and may improve high-intensity running performance during a simulated rugby match-play protocol, without improving shorter duration sprint and power-based efforts.
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Captain America can bring more than entertainment value to the public. The pop icon can also be used effectively in the science classroom, encouraging students to more effectively learn the content. How Captain America uses nutrients and how often he eats are novel ways to communicate real science. The point is to make a connection using science to explain how the superhero can run faster, jump higher, or lift more than is humanly possible. In this way fun, teachable moments are available for the educator.
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Optimal hydration is an essential consideration for athletic performance and it involves activities before, during and after exercise. Hence, adequate hydration not only provides benefits for health but also facilitate to maintain athletic performance. Therefore, the objective of the present study is to evaluate the importance of sports drinks as a performance prerequisites. The central aim of sports drinks utilization differ according to the mode of exercise regime but from a hydration point of view it depends upon rapid fluid absorption, reduction of physiological stress and faster recovery after exercise. So, proper intake of different essential macro and micro nutrients will help our body to hydrate. Sports drinks is a such a product which contain almost all the things which we lost during sports performance. Similarly, dehydration is a condition which cause negative impact on sports performance. The performance of the athlete is very much depends upon their hydration point of view, which may lead to cause both psychological as well as physiological illness. During activity the major fluid loss occurs through sweat. Thus it causes increment of heart rate, body temperature and also reduces the fluid absorption rate, making out body resistive against the minimum demand of work. All these problems can be overcome with the help of isotonic sports drinks. It helps replenish the lost fluid and also provide essential electrolytes and carbohydrates to the athletes which ultimately helped them to execute better performance output.
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New findings: What is the topic of this review? The nutritional strategies that athletes use during competition events to optimize performance and the reasons they use them. What advances does it highlight? A range of nutritional strategies can be used by competitive athletes, alone or in combination, to address various event-specific factors that constrain event performance. Evidence for such practices is constantly evolving but must be combined with understanding of the complexities of real-life sport for optimal implementation. Abstract: High-performance athletes share a common goal despite the unique nature of their sport: to pace or manage their performance to achieve the highest sustainable outputs over the duration of the event. Periodic or sustained decline in the optimal performance of event tasks, involves an interplay between central and peripheral phenomena that can often be reduced or delayed in onset by nutritional strategies. Contemporary nutrition practices undertaken before, during or between events include strategies to ensure the availability of limited muscle fuel stores. This includes creatine supplementation to increase muscle phosphocreatine content and consideration of the type, amount and timing of dietary carbohydrate intake to optimize muscle and liver glycogen stores or to provide additional exogenous substrate. Although there is interest in ketogenic low-carbohydrate high-fat diets and exogenous ketone supplements to provide alternative fuels to spare muscle carbohydrate use, present evidence suggests a limited utility of these strategies. Mouth sensing of a range of food tastants (e.g., carbohydrate, quinine, menthol, caffeine, fluid, acetic acid) may provide a central nervous system derived boost to sports performance. Finally, despite decades of research on hypohydration and exercise capacity, there is still contention around their effect on sports performance and the best guidance around hydration for sporting events. A unifying model proposes that some scenarios require personalized fluid plans while others might be managed by an ad hoc approach (ad libitum or thirst-driven drinking) to fluid intake.
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Black, CD, Haskins, KR, Bemben, MG, and Larson, RD. Carbohydrate mouth rinsing does not alter central or peripheral fatigue after high-intensity and low-intensity exercise in men. J Strength Cond Res 36(1): 142-148, 2022-Carbohydrate (CHO) mouth rinsing improves performance during endurance exercise. However, its ability to attenuate fatigue during strength-based exercise is less certain. This study sought to determine the effects of a CHO mouth rinse on torque production and voluntary activation (VA%) after high-intensity and low-intensity isometric exercise. Twelve male subjects (22.5 ± 2.3 years; 183.5 ± 6.5 cm; 82.2 ± 13.9 kg) completed 4 testing sessions in a double-blind crossover fashion. Knee extension maximal voluntary isometric strength (MVC) was assessed before(Pre), immediately (iPost-Ex), and 5 minutes (5-min Post Ex) after isometric exercise performed at 80% or 20% of MVC. An 8% CHO solution or placebo (PLA) was rinsed for 20 seconds after exercise. VA% was determined by twitch interpolation. A 2 condition (CHO vs. PLA) × 2 contraction intensity (20 vs. 80%) × 3 time (Pre, iPost Ex, and 5-min Post Ex) completely within subject-repeated measured analysis of variance was performed; statistical significance was set at p ≤ 0.05. Greater reductions in MVC were found at iPost-Ex after exercise at 20% compared with 80% of MVC (-25 ± 14% vs. -11 ± 8%; p < 0.001) as well as for VA% (-17 ± 14% vs. -8 ± 14%; p < 0.004). No differences were observed in the CHO vs. PLA condition (p ≥ 0.34). We were successful in eliciting differing levels of central and peripheral fatigue by exercising at a low and high intensity. Despite significantly larger declines in VA% after exercise at 20% of MVC, CHO mouth rinsing had no effects compared with placebo on any measured variable.
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The purpose of this double-blinded, crossover randomized, and counterbalanced study was to compare effects of ingesting a tepid commercially available carbohydrate-menthol containing sports drink (Menthol) and an isocaloric carbohydrate-containing sports drink (Placebo) on thermal perception and cycling endurance capacity “in a simulated home virtual cycling environment”. It was hypothesized that addition of menthol would improve indicators of thermal perception and improve endurance exercise capacity. Twelve healthy, endurance-trained males (age 29 ± 5 years, height 181 ± 6 cm, body mass 79 ± 2 kg and V O2max 57.3 ± 6.4 mL · kg-1 · min-1) completed two experimental trials on a stationary bicycle without external air flow. Each trial consisted of 1) cycling for 60 minutes at 90% of the first ventilatory threshold while receiving a fixed amount of Menthol or Placebo every 10 minutes followed immediately by 2) cycling until volitional exhaustion (TTE) at 105% of the intensity corresponding to the respiratory compensation point. TTE did not differ between both conditions (541 ± 177 and 566 ± 150 seconds for Menthol and Placebo; p>0.05) and neither did ratings of perceived thermal comfort or thermal sensation (p>0.05). Also, rectal temperature at the end of TTE was comparable between Menthol and Placebo trials (38.7 ± 0.2 °C and 38.7 ± 0.3 °C, respectively; p>0.05). The present results demonstrate that the addition of menthol to commercially available sports drink does not improve thermal comfort or endurance exercise capacity during ∼65 min of intense virtual cycling.
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This study aimed to clarify the effects of carbohydrate mouth rinse on exercise performance. We examined the effect of mouth rinse on fatigability. Thirty healthy male college students completed three trials with non mouth rinse (CON), mouth rinse intervention of 6% glucose (GMR), and artificial sweetener (PLA). Handgrip exercise was performed as a fatigue task. The subjects performed a 10-seconds maximal voluntary contraction (MVC) followed by a 40% MVC rhythmic grasping movement for 14 per minutes, followed by a 4-seconds rest. This set of exercises was performed for a total of ten sets. Mouth rinse was performed from the 5th set to the 10th set. The subjects were divided into three groups: L, M, and S, according to the degree of decrease in MVC due to fatigue in CON. The effect was evaluated using the rate of change in MVC after the mouth rinse. The evaluation was performed for each trail and group. In the L group, mouth rinse significantly improved the rate of change of MVC compared with the other trials (GMR vs. CON: P = 0.002; PLA vs. CON: P = 0.042). A significant trend was observed in the M (GMR vs. CON: P = 0.062), but not in the S. In conclusion, the effects of mouth rinse differed depending on fatigability in isometric hand grip performance, with mouth rinse inhibiting the decrease of motor fatigue. In addition, it was suggested that the sweetness of carbohydrates may have an effect on mouth rinse.
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Taste is one of our most powerful and useful senses, it has the potential to inform us of foods’ nutrient availability and readiness to eat, as well as evoke halcyon childhood memories and elicit seemingly unrelated physiological responses. Taste and experiences related to taste are made up of several sub-senses including smell, sight and receptor stimulation e.g. the trigeminal nerve with wasabi. So, taste, is not one sense, but a manifestation of multiple pathways working in synergy with one another. Through processes of evolutionary economy, the chemosensory highways that are responsible for our experience of taste, often share lanes with more deep rooted physiological effects such hedonic experiences, muscle recruitment or thermoregulation1. This is particularly apparent in individuals who have lost their sense of taste, but can still experience psychobiological responses to tastants, or when foods and beverages are served at different temperatures and their flavour profile appears to be intensified or supressed e.g. coffee, chocolate or wine. Over the last decade, sports scientists and nutrition practitioners have begun to explore the effects of taste in the lab and in the field, with further mechanistic insights from neuroscientists and practical application facilitated by food scientists. Two approaches to applying tastes have emerged in sports performance: swilling and ingestion. Swilling consists of taking in a small amount (typically 25-50ml of fluid) and coating the oral cavity with the substance before expectorating it, much like a sommelier would recommend one samples wine. Ingestion, one the other hand, is the ‘traditional’ approach to tasting – where one briefly tastes the substance and then swallows it, to undergo further digestion and metabolism. Both approaches have merit in the field and in the lab, so where appropriate are discussed in this article. In the following sections, we’ll explore the range of tastes that have been shown to be of benefit in sport and exercise to date, emerging tastes and the potential for placebo effects (and maximising them), concluding with a short checklist of which taste to administer and when to do so. It is important to emphasise that these supporting strategies can be easily personalised, and sports nutrition practitioners are encouraged to work closely with athletes and other support staff to achieve performance outcomes (Figure 1).
Presentation
Introduction: Carbohydrates are the most preferred nutritional ergogenic aids by elite athletes. Carbohydrates improve performance by delaying the release of muscle glycogen depots and optimizing blood glucose levels in long-lasting endurance exercises. In recent years it has been shown that carbohydrates rinse in the mouth without swallowing can improve performance. However, more research is needed to examine the effect of carbohydrate rinsing on strength and muscular endurance performance. The purpose of this research; examines the effect of rinsing of carbohydrate in the mouth on bench press strength and endurance performance. Metots: Twelve young men participated in this research for at least 3 days a week for upper body weight training for the last 12 years. After the familiarization test day, participants participated in a total of 2 test days with a randomized, counterbalanced, crossover study design: 6% (1.5 gr) weight / volume (w / v) carbohydrate mouth rinsing (CHO) with 25 ml water, mouth rinse with water (PLA). After a 10-hour night fasting one repetition maximum (1RM) was determined for strength and %40 1RM strength endurance test over a 3 sets until repetition to failure. Prior to strength and endurance measurements, participants rinse the solutions in their mouths for 10 seconds. During the test protocol heart rate (KAH), lactate (la), glucose (glu), fitness (zin) and ratings of perceived exertion (rpe) were measured. In the analysis of the data, single and two-way analysis of variance was used in repeated measures. Results: No significant differences was detected between trials as for strength heart rate (hr), blood glucose (bl), lactate (la), arousal (ar), ratings of perceived exertion (rpe). Discussions: This research has shown that orally rinsing of carbohydrate does not have a significant effect on upper body strength and muscular endurance performance. The results of the study are in parallel with the literature. In future studies, higher doses of carbohydrate may be rinsed in the mouth to investigate the effect on lower body strength and muscular endurance performance, especially when muscle activation percentage is low during maximal voluntary contraction.
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Bu kitap bölümü karbonhidrat tüketim zamanının performansa olumlu ve olumsuz etkilerini incelenmekte olup optimal tüketim aralığını ve optimal tüketim miktarını belirlemeyi amaç edinmiştir.
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Summary We performed successive H215O-PET scans on volunteers as they ate chocolate to beyond satiety. Thus, the sensory stimulus and act (eating) were held constant while the reward value of the chocolate and motivation of the subject to eat were manipulated by feeding. Non-specific effects of satiety (such as feelings of fullness and autonomic changes) were also present and probably contributed to the modulation of brain activity. After eating each piece of chocolate, subjects gave ratings of how pleasant/ unpleasant the chocolate was and of how much they did or did not want another piece of chocolate. Regional cerebral blood flow was then regressed against subjects' ratings. Different groups of structures were recruited selectively depending on whether subjects were eating chocolate when they were highly motivated to eat and rated the chocolate as very pleasant (subcallosal region, caudomedial orbitofrontal cortex (OFC), insula/oper-
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In response to a stimulus, a sensation is tridimensional: qualitative, quantitative, and affective. The affective part of sensation, pleasure or displeasure, depends on the qualities of the stimulus. Within a narrow range of intensity, chemical, thermal, and mechanical stimuli are able to arouse pleasure. In addition, pleasure depends on the internal state of the subject. This is easily observed in the case of temperature: pleasure is aroused by a warm stimulus in a hypothermic subject and by a cold stimulus in a hyperthermic subject. This property of a given stimulus to arouse pleasure or displeasure according to the internal state of the subject is termed alliethesia. Alliesthesia is also produced by chemical and mechanical stimuli. Acquired preferences or aversions for alimentary stimuli represent a case of alliesthesia. In the same way, the capacity of any indifferent stimulus to become rewarding, or punishing, by association with some reward or punishment, is also a case of alliethesia. In all cases, pleasure is a sign of a stimulus useful to the subject; displeasure a sign of danger. Usefulness and danger are judged by the central nervous system with reference to homeostasis and the set point of the implied regulation. Pleasure and displeasure thus appear to motivate useful behaviors.
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this paper investigates the mechanisms that sense oral fat and the neural representation of oral fat, of its palatability, and how that representation is affected by satiety
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Seven cyclists exercised at 70% of maximal O2 uptake (VO2max) until fatigue (170 +/- 9 min) on three occasions, 1 wk apart. During these trials, plasma glucose declined from 5.0 +/- 0.1 to 3.1 +/- 0.1 mM (P less than 0.001) and respiratory exchange ratio (R) fell from 0.87 +/- 0.01 to 0.81 +/- 0.01 (P less than 0.001). After resting 20 min the subjects attempted to continue exercise either 1) after ingesting a placebo, 2) after ingesting glucose polymers (3 g/kg), or 3) when glucose was infused intravenously ("euglycemic clamp"). Placebo ingestion did not restore euglycemia or R. Plasma glucose increased (P less than 0.001) initially to approximately 5 mM and R rose (P less than 0.001) to approximately 0.83 with glucose infusion or carbohydrate ingestion. Plasma glucose and R then fell gradually to 3.9 +/- 0.3 mM and 0.81 +/- 0.01, respectively, after carbohydrate ingestion but were maintained at 5.1 +/- 0.1 mM and 0.83 +/- 0.01, respectively, by glucose infusion. Time to fatigue during this second exercise bout was significantly longer during the carbohydrate ingestion (26 +/- 4 min; P less than 0.05) or glucose infusion (43 +/- 5 min; P less than 0.01) trials compared with the placebo trial (10 +/- 1 min). Plasma insulin (approximately 10 microU/ml) and vastus lateralis muscle glycogen (approximately 40 mmol glucosyl U/kg) did not change during glucose infusion, with three-fourths of total carbohydrate oxidation during the second exercise bout accounted for by the euglycemic glucose infusion rate (1.13 +/- 0.08 g/min).(ABSTRACT TRUNCATED AT 250 WORDS)
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The purpose of this study was to determine whether the postponement of fatigue in subjects fed carbohydrate during prolonged strenuous exercise is associated with a slowing of muscle glycogen depletion. Seven endurance-trained cyclists exercised at 71 +/- 1% of maximal O2 consumption (VO2max), to fatigue, while ingesting a flavored water solution (i.e., placebo) during one trial and while ingesting a glucose polymer solution (i.e., 2.0 g/kg at 20 min and 0.4 g/kg every 20 min thereafter) during another trial. Fatigue during the placebo trial occurred after 3.02 +/- 0.19 h of exercise and was preceded by a decline (P less than 0.01) in plasma glucose to 2.5 +/- 0.5 mM and by a decline in the respiratory exchange ratio (i.e., R; from 0.85 to 0.80; P less than 0.05). Glycogen within the vastus lateralis muscle declined at an average rate of 51.5 +/- 5.4 mmol glucosyl units (GU) X kg-1 X h-1 during the first 2 h of exercise and at a slower rate (P less than 0.01) of 23.0 +/- 14.3 mmol GU X kg-1 X h-1 during the third and final hour. When fed carbohydrate, which maintained plasma glucose concentration (4.2-5.2 mM), the subjects exercised for an additional hour before fatiguing (4.02 +/- 0.33 h; P less than 0.01) and maintained their initial R (i.e., 0.86) and rate of carbohydrate oxidation throughout exercise. The pattern of muscle glycogen utilization, however, was not different during the first 3 h of exercise with the placebo or the carbohydrate feedings. The additional hour of exercise performed when fed carbohydrate was accomplished with little reliance on muscle glycogen (i.e., 5 mmol GU X kg-1 X h-1; NS) and without compromising carbohydrate oxidation. We conclude that when they are fed carbohydrate, highly trained endurance athletes are capable of oxidizing carbohydrate at relatively high rates from sources other than muscle glycogen during the latter stages of prolonged strenuous exercise and that this postpones fatigue.
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This study compared the polysaccharide and sugar taste preferences of humans and four rodent species (laboratory rats, Rattus norvegicus; Golden Syrian hamsters, Mesocricetus auratus; Mongolian gerbils, Meriones unguiculatus; Egyptian spiny mice, Acomys cahirinus). In Experiment 1 human subjects rated the pleasantness, sweetness, and flavor intensity of polysaccharide (Polycose), sucrose, and maltose solutions at concentrations of 0.0125 M to 0.4 M, and 1% to 32% concentrations. At the higher molar concentrations Polycose was rated as less sweet and less pleasant than the sucrose and maltose solutions; there were no differences in the flavor intensity ratings. With the percent concentrations Polycose was rated as less sweet and less flavorable as the sucrose and maltose solutions; there were no reliable differences in the pleasantness ratings. In Experiment 2, the Polycose, sucrose, and maltose preferences of rats, hamsters, gerbils, and spiny mice were compared using 24 hr two-bottle tests (saccharide vs. water) at concentrations of 0.001 M, 0.005 M, 0.01 M, and 0.1 M. In general, the rats displayed stronger preferences for Polycose and maltose than did the other three species. In addition, the gerbils showed a stronger Polycose preference at the 0.1 M concentration than did the hamsters and spiny mice, and the spiny mice display a weaker preference for sucrose than did the other three species. Within species comparisons revealed that all four species displayed preferences for Polycose that were as strong or stronger than their preferences for sucrose and maltose. With only a few exceptions, male and female rodents did not differ in their saccharide preferences. Thus, while rats show the most robust Polycose preference of the four rodent species, all four species were attracted to the taste of polysaccharides. Humans, on the other hand, reported that Polycose solutions were unpleasant. The results suggest that rodents have taste receptors for starch-derived polysaccharides that humans lack.
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Cephalic phase digestive responses may be particularly critical in determining our various reactions to different diets, since these responses are the first physiological adjustments to food. The potential importance of the cephalic responses is also underscored by the fact that many of the most important food attributes for humans--color, appearance, flavor, aroma, and texture--can influence the individual's gastrointestinal physiology solely by affecting these early metabolic responses. The present survey examines in some detail the data available for one of the responses, the cephalic phase insulin response. Specific shortcomings of the existing analyses are discussed. In addition, given the possible significance of these reflexes, several suggestions for improvements of experimental protocols are considered, and a summary of major experimental questions is provided.
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There is a great demand for perceptual effort ratings in order to better understand man at work. Such ratings are important complements to behavioral and physiological measurements of physical performance and work capacity. This is true for both theoretical analysis and application in medicine, human factors, and sports. Perceptual estimates, obtained by psychophysical ratio-scaling methods, are valid when describing general perceptual variation, but category methods are more useful in several applied situations when differences between individuals are described. A presentation is made of ratio-scaling methods, category methods, especially the Borg Scale for ratings of perceived exertion, and a new method that combines the category method with ratio properties. Some of the advantages and disadvantages of the different methods are discussed in both theoretical-psychophysical and psychophysiological frames of reference.
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The purpose of this study was to investigate the effect of 7% carbohydrate-electrolyte (CE) drink on sprint capacity immediately following 50 min of high-intensity cycling. After an overnight 12-hr fast, 8 trained male cyclists performed two 50-min simulated time trials on a Monark stationary cycle ergometer. Subjects consumed either the CE or a flavored water placebo (PL) at 10, 20, 30, and 40 min during the time trial. At the conclusion of each 50-min time trial, subjects immediately performed a Wingate Anaerobic Power Test. Peak power, mean power, and minimum power were significantly higher for the CE trials, whereas mean RPE was significantly lower. Mean heart rate and fatigue index were not different between trials. These results suggest that sprint performance following a high-intensity simulated time trial of only 50 min can be improved with periodic consumption of CE during the ride, particularly following an overnight fast, when liver glycogen is likely to be low. These findings have implications for competitive cycling, where sprint capacity at the conclusion of a race is an important determinant of success.
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This study determined the effects of fluid and carbohydrate ingestion on performance, core temperature, and cardiovascular responses during intense exercise lasting 1 h. On four occasions, eight men cycled at 80 +/- 1% (+/- SEM) of VO2max for 50 min followed by a performance test. During exercise, they consumed either a large volume (1330 +/- 60 ml) of a 6% carbohydrate (79 +/- 4 g) solution or water or a small volume (200 +/- 10 ml) of a 40% maltodextrin (79 +/- 4 g) solution or water. These trials were pooled so the effects of fluid replacement (Large FR vs Small FR) and carbohydrate ingestion (CHO vs NO CHO) could be determined. Performance times were 6.5% faster during Large FR than Small FR and 6.3% faster during CHO than NO CHO (P < 0.05). At 50 min, heart rate was 4 +/- 1 b.min-1 lower and esophageal temperature was 0.33 +/- 0.04 degrees C lower during Large FR than Small FR (P < 0.05) but no differences occurred between CHO and NO CHO. In summary, Large FR slightly attenuates the increase in heart rate and core temperature which occurs during Small FR. Both fluid and carbohydrate ingestion equally improve cycling performance and their effects are additive.
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The effects of carbohydrate supplementation on high-intensity exercise performance were examined in 5 moderately-trained subjects (age = 28.4 +/- 1.5 yr; ht = 171.0 +/- 4.3 cm; wt = 66.25 +/- 6.32 kg). High-intensity exercise tests (initiated at the power output (PO) associated with 90% VO2 peak [mean = 201 +/- 21 watts] x 60 min, with drop-off in PO allowed over time) were completed under the following randomized double blind conditions: 1) pre-exercise glucose polymer (G)/placebo during exercise (G/P), 2) G pre-exercise and during exercise (G/G), and 3) placebo pre-exercise and during exercise (P/P). Subjects ingested 300 ml of a sweetened placebo or a similarly flavored 10% G solution, immediately prior to and every 15 min during exercise. No differences were observed in PO among the 3 treatments until min 40-60 where PO was greater with G. This resulted in significantly greater total work (and less drop-off in PO) with G (G/P = 619 +/- 234kJ [14.5% lower than the value associated with 201 watts maintained for 60 min (724kJ)], G/G = 599 +/- 235 kJ [17.3% lower than the value associated with 201 watts maintained for 60 min]) compared with placebo (P/P = 560 +/- 198 kJ [22.7% drop-off in average PO]) (p < 0.05). VO2 followed a similar pattern with no difference in VO2 over min 0-40 and significantly higher VO2 in G/P and a trend for higher VO2 in G/G during min 40-60 compared to placebo. Results of the present study indicate that, compared to placebo, pre-exercise ingestion of G (30 g in 10% solution) results in less drop-off in PO during 1 hour of high-intensity exercise performance, and that no further benefit is observed when the same amount of G is also ingested every 15 min during exercise.
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The purpose of this investigation was to determine the effect of caffeine ingestion on work output at various levels of perceived exertion during 30 min of isokinetic variable-resistance cycling exercise. Ten subjects completed six trials 1 hr after consuming either 6 mg.kg-1 caffeine (3 trials) or a placebo (3 trials). During each trial the subjects cycled at what they perceived to be a rating of 9 on the Borg rating of perceived exertion scale for the first 10 min, a rating of 12 for the next 10 min, and a rating of 15 for the final 10 min. Total work performed during the caffeine trials averaged 277.8 +/- 26.1 kJ, whereas the mean total work during the placebo trials was 246.7 +/- 21.5 kJ (p < .05). However, there were no significant differences between the conditions in respiratory exchange ratio. These data suggest that caffeine may play an ergogenic role in exercise performance by altering both neural perception of effort and substrate availability.
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The extensive use of performance tests in diet intervention studies mirrors the importance of such a measurement. Although many different endurance performance tests have been used in the past, the majority of these different protocols has never been validated. In this study reproducibility of three different endurance performance tests was evaluated. Thirty well-trained subjects were matched on age, weight, and Wmax and divided into three subgroups. Each group of subjects performed one of three exercise protocols: protocol (A) consisted of cycling at 75% Wmax until exhaustion. In (B) subjects received a preload of 45 min 70% Wmax and then performed as much work as possible in 15 min. (C) consisted of a time trial, in which subjects had to complete a preset amount of work as fast as possible. Each subject performed one of the trials six times. Coefficient of variation (CV) was calculated for each protocol. CV(A) was 26.6%, CV(B) 3.49%, and CV(C) 3.35%. It was concluded that reproducibility of a test at 75% Wmax until exhaustion is poor and these tests are not reliable. Time trial protocols may result in better performance evaluation.
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Twelve highly trained male runners ran 15 km at self-selected pace on a treadmill in warm conditions to demonstrate differences in physiological responses, fluid preferences, and performance when ingesting sports drinks or plain water before and during exercise. One hour prior to the start of running, an equal volume (1,000 ml) of either water or a 6% or an 8% carbohydrate-electrolyte (CE) drink was ingested. Blood glucose was significantly higher 30 min following ingestion of 6% and 8% CE compared to water, significantly lower at 60 min postingestion with both sports drinks than with water, but similar after 7.5 km of the run for all beverages. During the first 13.4 km, oxygen uptake and run times were not different between trials; however, the final 1.6-km performance run was faster with both CE drinks compared to water. Despite a lower preexercise blood glucose, CE consumption prior to and during exercise significantly improved performance in last 1.6 km of a 15-km run compared to water.