Effect of carbohydrate and prolonged exercise on affect and perceived exertion

Trends and Missing Links in (De)Hydration Research: A Narrative Review

Despite decades of literature on (de)hydration in healthy individuals, many unanswered questions remain. To outline research and policy priorities, it is fundamental to recognize the literature trends on (de)hydration and identify current research gaps, which herein we aimed to pinpoint. From a representative sample of 180 (de)hydration studies with 4350 individuals, we found that research is mainly limited to small-scale laboratory-based sample sizes, with high variability in demographics (sex, age, and level of competition); to non-ecological (highly simulated and controlled) conditions; and with a focus on recreationally active male adults (e.g., Tier 1, non-athletes). The laboratory-simulated environments are limiting factors underpinning the need to better translate scientific research into field studies. Although, consistently, dehydration is defined as the loss of 2% of body weight, the hydration status is estimated using a very heterogeneous range of parameters. Water is the most researched hydration fluid, followed by alcoholic beverages with added carbohydrates (CHO). The current research still overlooks beverages supplemented with proteins, amino acids (AA), and glycerol. Future research should invest more effort in "real-world" studies with larger and more heterogeneous cohorts, exploring the entire available spectrum of fluids while addressing hydration outcomes more harmoniously.

The acute effects of pre- and mid-exercise carbohydrate ingestion on the immunoregulatory stress hormone release in experienced endurance athletes-a systematic review

Background

In times of physical stress, the body orchestrates a multisystemic regulatory response. The hormones epinephrine and norepinephrine play a role in the immediate regulation chain, while cortisol is involved in delayed regulation. The release of those stress hormones in response to exercise has previously been reported to elicit diverse immune reactions.

Objective

The aim of this systematic review was to examine and present the acute effects of immediate pre- and mid-exercise carbohydrate ingestion on cortisol, epinephrine and norepinephrine levels in experienced endurance athletes.

Methods

A systematic literature search was conducted using PubMed, Cochrane Library and Web of Science in accordance with PRISMA guidelines up to February 2023. Randomized controlled trials in English or German language were included if baseline and at least two follow-up measures of blood plasma or serum of chosen stress hormones (cortisol, epinephrine, norepinephrine) were collected in response to prolonged continuous endurance activity. Eligibility furthermore required an acute carbohydrate ingestion of at least 30 g of carbohydrates per hour no more than 30 min before start of the exercise, as well as a placebo-controlled study design.

Results

Eleven studies of moderate to high quality were included in this review. Carbohydrate ingestion of at least 30 g per hour was able to attenuate rises in cortisol concentration in majority of the included studies. Epinephrine levels were considerably lower with ingestion of carbohydrates compared to placebo in all studies. Norepinephrine concentrations were largely unaffected by acute carbohydrate feeding.

Conclusion

Pre- and mid-exercise ingestion of carbohydrates seems an effective dietary strategy to attenuate rises in cortisol and epinephrine levels and, thus, an effective countermeasure for endurance exercise-induced increases in stress hormone levels.

Carbohydrate Nutrition and Skill Performance in Soccer

In soccer, players must perform a variety of sport-specific skills usually during or immediately after running, often at sprint speed. The quality of the skill performed is likely influenced by the volume of work done in attacking and defending over the duration of the match. Even the most highly skilful players succumb to the impact of fatigue both physical and mental, which may result in underperforming skills at key moments in a match. Fitness is the platform on which skill is performed during team sport. With the onset of fatigue, tired players find it ever more difficult to successfully perform basic skills. Therefore, it is not surprising that teams spend a large proportion of their training time on fitness. While acknowledging the central role of fitness in team sport, the importance of team tactics, underpinned by spatial awareness, must not be neglected. It is well established that a high-carbohydrate diet before a match and, as a supplement during match play, helps delay the onset of fatigue. There is some evidence that players ingesting carbohydrate can maintain sport-relevant skills for the duration of exercise more successfully compared with when ingesting placebo or water. However, most of the assessments of sport-specific skills have been performed in a controlled, non-contested environment. Although these methods may be judged as not ecologically valid, they do rule out the confounding influences of competition on skill performance. The aim of this brief review is to explore whether carbohydrate ingestion, while delaying fatigue during match play, may also help retain sport soccer-specific skill performance.

L-menthol administration facilitates breathing comfort during exhaustive endurance running and improves running capacity in well-trained runners: A randomized crossover study

ABSTRACTThis study aimed to clarify the contribution of L-menthol administration to endurande exercise capacity. Thirteen male runners (age, 35.8 ± 7.8 years; peak oxygen uptake, 62.7 ± 6.8 mL kg-1 min-1) ran on treadmills at fixed intensities of their anaerobic thresholds to exhaustion. All participants underwent three trials-water ingestion (W-IG), L-menthol mouth rinsing (M-MR), and L-menthol ingestion (M-IG)- in a random order every 5 min while running. Breathing comfort (BC) was measured immediately after fluid intake. Dyspnea threshold against external inspiratory resistance was examined before and after the running test. The running time with M-IG (1683.9 ± 520.3 s) was longer than that with W-IG (1410.2 ± 465.9 s, effect size [ES] = 0.55). BC with M-IG (2.00 ± 0.74) was higher than that with W-IG (0.42 ± 0.79) at exhaustion (ES > 2.00). The dyspnea threshold after running decreased to 19.2 ± 7.6 cm H₂O L-1 s-1 with W-IG, whereas that with M-MR (26.2 ± 6.5 cm H₂O L-1 s-1) and M-IG (29.2 ± 2.8 cm H₂O L-1 s-1) remained high (p for interaction < 0.001). M-IG facilitated BC during running, improved endurance capacity, and prevented decreases in the dyspnea threshold against external inspiratory resistance after exhaustive running.HighlightsL-menthol ingestion facilitated breathing comfort during high intensity endurance running and improved exhaustive endurance running capacity.Even after exhaustion, L-menthol solution relieved dyspnea sensitivity against external inspiratory resistance.L-menthol ingestion might help athletes improve their endurance running capacity.

A systematic narrative review of extrinsic strategies to improve affective responses to exercise

Background

Extrinsic strategies affect the exercise experience but fall outside the frequency, intensity, time, and type (i.e., dose-determining) principles. To our knowledge, no systematic review has focused on extrinsic strategies to influence the affective responses to exercise. The objective was to identify extrinsic strategies that seek to influence affective responses during exercise and other motivationally relevant variables including post-exercise momentary affective valence, remembered and forecasted pleasure, and enjoyment.

Methods

For inclusion, eligible articles reported peer-reviewed original research, used acute bouts of exercise, and used a dimensional approach for measuring affective responses or measured enjoyment post-exercise. Web of Science, PubMed, and PsychINFO databases were last searched on 10th September 2021. Quality assessment was completed following the Effective Public Health Practice Project approach. Results were presented using a narrative synthesis.

Results

125 studies were included with sample descriptions, study design (extrinsic strategies, mode, type, intensity, and duration), measurement details, and results summarised for each study.

Conclusions

71% of studies were categorised as Weak according to the quality assessment tool with sampling practices (self-referred participants) and poor reporting of participant withdrawals/drop-outs the predominant reasons for Weak ratings. A wide variety of extrinsic strategies were reported with music, music videos, immersive virtual reality, outdoor exercise, caffeine, high-to-low pattern of exercise intensity, self-selected exercise intensity, and manipulation of self-efficacy offering promise as suitable strategies to positively change how people feel during exercise.

Systematic Review Registration

https://osf.io/jbh8v/.

Effects of caffeine, methylliberine, and theacrine on vigilance, marksmanship, and hemodynamic responses in tactical personnel: a double-blind, randomized, placebo-controlled trial

Background

Tactical athletes require fast reaction times (RT) along with high levels of vigilance and marksmanship performance. Caffeine has been shown to improve these measures but also results in increased blood pressure and jitteriness. Research on other purine alkaloids, such as methylliberine and theacrine, has suggested they do not increase blood pressure or jitteriness to the same extent, but their impact on tactical performance is unknown.

Methods

A between-subjects, randomized, placebo-controlled design was used to test the effects of placebo (PLA), 300 mg caffeine (CAF), and a combination of 150 mg caffeine, 100 mg methylliberine, and 50 mg theacrine (CMT) on RT and marksmanship along with hemodynamic and arousal measures following a sustained vigilance task in tactical personnel (n = 48). Following consumption of the supplement, participants underwent a 150-min protocol consisting of two rounds. Each round began with leisurely reading followed by a 30-min vigilance task before beginning two trials of movement and marksmanship tasks. Hemodynamics and felt arousal were assessed throughout the protocol. Composite Z-scores were calculated for overall performance measures at each timepoint, and mixed-effects models were used to assess differences in RT, accuracy, and composite Z-scores along with hemodynamics and felt arousal. An α-level of 0.05 was used to determine statistical significance, and Cohen’s d was used to quantify effect sizes.

Results

A Group-by-Time interaction for vigilance RT (P = 0.038) indicated improvements for both CAF and CMT from round 1 to round 2 (P < 0.01) while PLA did not change (P = 0.27). No Group main effects or Group-by-Time interactions were found for movement or marksmanship performance (P > 0.20). Group main effects for systolic (SBP; P = 0.001) and diastolic blood pressure (DBP; P = 0.028) indicated higher SBP in CAF (P = 0.003, d= 0.84) and CMT (P = 0.007, d= 0.79) compared to PLA but only higher DBP in CAF (P = 0.025, d= 0.74). No Group-by-Time interaction or Group main effect was found for felt arousal (P > 0.16).

Conclusions

These findings suggest similar benefits on RT during a vigilance task between CAF, containing 300 mg caffeine, and CMT above PLA, though CAF resulted in slightly less favorable hemodynamic changes. This study is the first to provide data showing similar efficacy of combined caffeine, methylliberine, and theacrine compared to double the caffeine dose consumed alone on vigilance RT but without a significant rise in DBP above PLA in tactical personnel.

Impact of dehydration on perceived exertion during endurance exercise: A systematic review with meta-analysis

Background

Understanding the impact of stressors on the rating of perceived exertion (RPE) is relevant from a performance and exercise adherence/participation standpoint. Athletes and recreationally active individuals dehydrate during exercise. No attempt has been made to systematically determine the impact of exercise-induced dehydration (EID) on RPE.

Objective

The present meta-analysis aimed to determine the effect of EID on RPE during endurance exercise and examine the moderating effect of potential confounders.

Data analyses

Performed on raw RPE values using random-effects models weighted mean effect summaries and meta-regressions with robust standard errors, and with a practical meaningful effect set at 1 point difference between euhydration (EUH) and EID. Only controlled crossover studies measuring RPE with a Borg scale in healthy adults performing ≥30 min of continuous endurance exercise while dehydrating or drinking to maintain EUH were included.

Results

Sixteen studies were included, representing 147 individuals. Mean body mass loss with EUH was 0.5 ± 0.4%, compared to 2.3 ± 0.5% with EID (range 1.7-3.1%). Within an EID of 0.5-3% body mass, a maximum difference in RPE of 0.81 points (95% CI: 0.36-1.27) was observed between conditions. A meta-regression revealed that RPE increases by 0.21 points for each 1% increase in EID (95% CI: 0.12-0.31). Humidity, ambient temperature and aerobic capacity did not alter the relationship between EID and RPE.

Conclusion

Therefore, the effect of EID on RPE is unlikely to be practically meaningful until a body mass loss of at least 3%.

Ingestion of Carbohydrate Solutions and Mouth Rinse on Mood and Perceptual Responses during Exercise in Triathletes

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.

Menthol Mouth Rinsing Is More Than Just a Mouth Wash-Swilling of Menthol to Improve Physiological Performance

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).

Does Emotion Regulation Predict Gains in Exercise-Induced Fitness? A Prospective Mixed-Effects Study with Elite Helicopter Pilots

Emotion regulation (ER) is a strong predictor of different aspects of mental health and wellbeing. However, only recently has ER been examined in relation to physical activity and its effects on fitness. In the present study, 26 elite helicopter pilots, serving in the Spanish Air Force, were physically trained for 6 months, and their level of fitness (maximum oxygen consumption and time to exhaustion in a treadmill-running test) was assessed before and after that period. Additionally, two indices of emotion regulation (general adaptiveness of ER strategies, as measured by the Emotion Regulation Questionnaire (ERQ), and negative urgency, as measured by the UPPS-P questionnaire) measured at baseline were used as prospective predictors of fitness improvement. After controlling for individual features, baseline fitness, and type of training, better emotion regulation strategies (more cognitive reappraisal plus less expressive suppression) predicted larger fitness gains (p = 0.028). Incidental emotion regulation, as measured by the negative urgency index, failed to predict pre–post-fitness changes (p = 0.734). These results suggest that fostering emotion regulation skills may improve the effectiveness of fitness training programs.

Effects of Carbohydrate Mouth Rinsing on Salivary Lysozyme, Mood States and Running Performance Among Recreational Runners

Introduction

Carbohydrate (CHO) mouth rinsing can enhance sports performance through a central action mediated by receptors in the mouth. This study examined the effect of a CHO mouth rinse on salivary lysozyme concentrations, mood states and running performances.

Methods

Ten males recreational runners were randomised to three running trials with a 1 week recovery period between the trials. Each trial involved running at 75% maximum heart rate (HRmax) for 1 h, followed by a 15 min time trial. The participants used a CHO mouth rinse, placebo (PLA) solution or control (CON, no solution) every 15 min during the exercise. Heart rate (HR), rating of perceived exertion (RPE) and mood states were recorded pre-, during and post-exercise. Saliva samples were collected pre-, post- and 1 h post-exercise.

Results

There was no significant interaction and time effect (P > 0.05) on the salivary lysozyme concentration and running performance, but it was significant (P < 0.05) for HR and RPE (increase in all trials). However, there was no significant difference (P > 0.05) in salivary lysozyme concentrations, running performances, HR values or RPE between the trials. Mood states were not significantly different (P > 0.05) between the trials, but one of the mood sub-scales showed a significant (P < 0.001) time effect (increase fatigue in all trials).

Conclusion

CHO mouth rinsing did not affect physiological parameters, salivary lysozyme concentrations, mood states or running performance among recreational runners.

Potato ingestion is as effective as carbohydrate gels to support prolonged cycling performance

Carbohydrate (CHO) ingestion is an established strategy to improve endurance performance. Race fuels should not only sustain performance but also be readily digested and absorbed. Potatoes are a whole-food-based option that fulfills these criteria, yet their impact on performance remains unexamined. We investigated the effects of potato purée ingestion during prolonged cycling on subsequent performance vs. commercial CHO gel or a water-only condition. Twelve cyclists (70.7 ± 7.7 kg, 173 ± 8 cm, 31 ± 9 yr, 22 ± 5.1% body fat; means ± SD) with average peak oxygen consumption (V̇o_2peak) of 60.7 ± 9.0 mL·kg⁻¹·min⁻¹ performed a 2-h cycling challenge (60–85% V̇o_2peak) followed by a time trial (TT; 6 kJ/kg body mass) while consuming potato, gel, or water in a randomized-crossover design. The race fuels were administered with [U-¹³C₆]glucose for an indirect estimate of gastric emptying rate. Blood samples were collected throughout the trials. Blood glucose concentrations were higher (P < 0.001) in potato and gel conditions compared with water condition. Blood lactate concentrations were higher (P = 0.001) after the TT completion in both CHO conditions compared with water condition. TT performance was improved (P = 0.032) in both potato (33.0 ± 4.5 min) and gel (33.0 ± 4.2 min) conditions compared with water condition (39.5 ± 7.9 min). Moreover, no difference was observed in TT performance between CHO conditions (P = 1.00). In conclusion, potato and gel ingestion equally sustained blood glucose concentrations and TT performance. Our results support the effective use of potatoes to support race performance for trained cyclists.

NEW & NOTEWORTHY The ingestion of concentrated carbohydrate gels during prolonged exercise has been shown to promote carbohydrate availability and improve exercise performance. Our study aim was to expand and diversify race fueling menus for athletes by providing an evidence-based whole-food alternative to the routine ingestion of gels during training and competition. Our work shows that russet potato ingestion during prolonged cycling is as effective as carbohydrate gels to support exercise performance in trained athletes.

Effect of carbohydrate-electrolyte consumption on insulin, cortisol hormones and blood glucose after high-intensity exercise

Objective: This study aimed to examine the effect of CHO-E consumption after high-intensity exercise on insulin, cortisol hormones and blood glucose responses, which is important for performance and recovery in athletes. Methods: Sixteen volunteers, male athletes, participated into this study. Athletes were divided into two groups as experiment (CHO-E) and placebo (PLA). Blood was taken from the athletes three times as basal, post-exercise (PE) and 2 h after ingestion of supplement (PS). Results: When inter-group comparisons, insulin was significantly higher in the CHO-E group than the PLA group at the PS phase (p < .05). Cortisol significantly decreased in the CHO-E group at the PS compared to the PE (p < .05). Conclusions: Carbohydrate-electrolyte consumption after high-intensity exercise, accelerates the recovery process by providing optimal recovery, and enable the metabolism to remain in the anabolic state by preventing it from entering in the catabolic process as well as provides hormonal balance in metabolism.

Impact of a Carbohydrate Mouth Rinse on Quadriceps Muscle Function and Corticomotor Excitability

PURPOSE

The purpose of this investigation is to determine the effects of different forms of a CHO MR on quadriceps muscle performance and corticospinal motor excitability.

METHODS

Ten subjects (5 females, 5 males; 25±1 years; 1.71±0.03 m 73±5 kg) completed 4 trials. A different MR condition was applied during each trial (Placebo (PLA), 6.4% glucose (GLU), 6.4% maltose (MAL), 6.4% maltodextrin (MDX)). Maximal voluntary contraction (MVIC) of the right quadriceps and motor-evoked potential (MEP) of the right rectus femoris was determined pre (10 min), immediately after, and post (10 min) MR. MEP was precipitated by transcranial magnetic stimulation (TMS) during muscle contraction (50% of MVIC). MR was held in the mouth for 20 s and treatments were applied using a Latin square design. The relative change in MEP from pre-measures was different across treatments (p=0.025) but was not different across time (p=0.357).

RESULTS

Relative change in MEP was greater for all CHO conditions immediately after (GLU=2.58±5.33%; MAL=3.92±3.90%; MDX=18.28±5.57%) and 10 min after (GLU=14.09±13.96%; MAL=8.64±8.67%; MDX=31.54±12.77%) MR compared to PLA (Immediately after=-2.19±4.25%, 10 min=-13.41±7.46%). The relative change in MVC was greater for CHO conditions immediately (GLU=3.98±2.49%; MAL=5.89±2.29.90%; MDX=7.66±1.93%) and 10 min after (GLU=7.22±2.77%; MAL=10.26±4.22%; MDX=10.18±1.50%) MR compared to PLA (Immediately after=-3.24±1.50%, 10 min=-6.46±2.22%).

CONCLUSIONS

CHO MR increased corticospinal motor excitability and quadriceps muscle performance immediately and 10 min after application; however, the form of CHO used did not influence this response.

No effect of meal intake on physiological or perceptual responses to self-selected high intensity interval exercise (HIIE)

The present study examined the effect of meal intake on physiological and psychological indices during self-selected high intensity interval exercise (HIIE). Seventeen active men and women (age = 26.4 ± 5.8 yr) completed ramp cycle ergometry to determine maximal oxygen uptake and peak power output. On two subsequent days, they performed a session of self-selected HIIE consisting of ten 1 min bouts separated by 1 min recovery in the fed or fasted state, whose order was randomized. Meal intake consisted of a banana and a Zone™ bar containing 315 kcal, which were ingested 2 h pre-exercise, and the fasted state required no food for > 12 h pre-exercise. Participants ingested an identical meal the evening before each session. Heart rate (HR), oxygen uptake (VO₂), blood glucose and blood lactate concentration, rating of perceived exertion (RPE), affect, and enjoyment were measured during exercise. Irrespective of fed state, both bouts elicited intensities equal to 94% HRmax which represents HIIE. Our results showed no difference in HR (174.0 ± 13.5 vs. 173.2 ± 12.9 b/min in fed and fasted state, p = 0.17), VO₂ (2.43 ± 0.54 vs. 2.40 ± 0.52 L/min in fed and fasted state, p = 0.14), RPE (p = 0.44), affect (p = 0.79), or enjoyment (103 ± 14 vs. 101 ± 13, p = 0.77) between the fed and fasted state. Despite its high reliance on carbohydrate, performance and perception of low-volume HIIE are not altered by ingestion of a meal before exercise.

The ergogenic potency of carbohydrate mouth rinse on endurance running performance of dehydrated athletes

PURPOSE

To examine the effect of carbohydrate (CHO) mouth rinsing on endurance running responses and performance in dehydrated individuals.

METHODS

In a double blind, randomised crossover design, 12 well-trained male runners completed 4 running time to exhaustion (TTE) trials at a speed equivalent to 70% of VO_2peak in a thermoneutral condition. Throughout each run, participants mouth rinsed and expectorated every 15 min either 25 mL of 6% CHO or a placebo (PLA) solution for 10 s. The four TTEs consisted of two trials in the euhydrated (EU-CHO and EU-PLA) and two trials in the dehydrated (DY-CHO and DY-PLA) state. Prior to each TTE run, participants were dehydrated via exercise and allowed a passive rest period during which they were fed and either rehydrated equivalent to their body mass deficit (i.e., EU trials) or ingested only 50 mL of water (DY trials).

RESULTS

CHO mouth rinsing significantly improved TTE performance in the DY compared to the EU trials (78.2 ± 4.3 vs. 76.9 ± 3.8 min, P = 0.02). The arousal level of the runners was significantly higher in the DY compared to the EU trials (P = 0.02). There was no significant difference among trials in heart rate, plasma glucose and lactate, and psychological measures.

CONCLUSIONS

CHO mouth rinsing enhanced running performance significantly more when participants were dehydrated vs. euhydrated due to the greater sensitivity of oral receptors related to thirst and central mediated activation. These results show that level of dehydration alters the effect of brain perception with presence of CHO.

Effects of Carbohydrate, Caffeine, and Guarana on Cognitive Performance, Perceived Exertion, and Shooting Performance in High-Level Athletes

Purpose: To investigate the effect of ingesting carbohydrate (CHO), caffeine  (CAF), and a guarana complex (GUAc) during a running exercise on cognitive performance, rating of perceived exertion (RPE), and shooting performance in high-level modern pentathlon athletes. Methods: A total of 10 athletes completed 4 counterbalanced sessions within a 2-wk period, corresponding to ingestions of CHO (30 g), GUAc (300 mg), CAF (200 mg), or placebo. The exercise involved a 40-min run on a treadmill at a steady speed, previously determined as a "somewhat hard" exercise (RPE 13). Shooting and cognitive performance (Simon task) were assessed in 3 phases: before exercise and ingestion, before exercise and after half ingestion, and after exercise and full ingestion. Drinks were consumed 40 min (250 mL) and 5 min (125 mL) prior to exercise and after 20 min of running (125 mL). RPE was assessed at 10-min intervals during exercise. Results: There was an interaction between drink and exercise on mean reaction time (P = .01, ηp2=.41 ) and a drink effect on RPE (P = .01, ηp2=.15 ). CHO, CAF, and GUAc enhanced the speed of information processing after exercise (P = .003, P = .004, and P = .04, respectively), but only CAF and GUAc decreased RPE (P = .002 and P = .02, respectively). Conclusion: The results highlight a beneficial effect of nutritional supplements on information processing and RPE. This finding is particularly interesting as decision-making processes are crucial in the performance of many sports.

Sugar rush or sugar crash? A meta-analysis of carbohydrate effects on mood

The effect of carbohydrate (CHO) consumption on mood is much debated, with researchers reporting both mood improvements and decrements following CHO ingestion. As global consumption of sugar-sweetened products has sharply increased in recent years, examining the validity of claims of an association between CHOs and mood is of high importance. We conducted a systematic review and meta-analysis to evaluate the relationship between acute CHO ingestion and mood. We examined the time-course of CHO-mood interactions and considered the role of moderator variables potentially affecting the CHO-mood relationship. Analysis of 176 effect sizes (31 studies, 1259 participants) revealed no positive effect of CHOs on any aspect of mood at any time-point following their consumption. However, CHO administration was associated with higher levels of fatigue and less alertness compared with placebo within the first hour post-ingestion. These findings challenge the idea that CHOs can improve mood, and might be used to increase the public's awareness that the 'sugar rush' is a myth, inform health policies to decrease sugar consumption, and promote healthier alternatives.

The effect of carbohydrate mouth rinse on performance, biochemical and psychophysiological variables during a cycling time trial: a crossover randomized trial

BACKGROUND

The hypothesis of the central effect of carbohydrate mouth rinse (CMR) on performance improvement in a fed state has not been established, and its psychophysiological responses have not yet been described. The aim of this study was to evaluate the effect of CMR in athletes fed state on performance, biochemical and psychophysiological responses compared to ad libitum water intake.

METHODS

Eleven trained male cyclists completed a randomized, crossover trial, which consisted of a 30 km cycle ergometer at self-selected intensity and in a fed state. Subjects were under random influence of the following interventions: CMR with a 6% unflavored maltodextrin solution; mouth rinsing with a placebo solution (PMR); drinking "ad libitum" (DAL). The time for completion of the test (min), heart rate (bpm) and power (watts), rating of perceived exertion (RPE), affective response, blood glucose (mg/dL) and lactate (mmol/DL), were evaluated before, during and immediately after the test, while insulin (uIL/mL), cortisol (μg/dL) and creatine kinase (U/L) levels were measured before, immediately after the test and 30 min after the test.

RESULTS

Time for completion of the 30 km trial did not differ significantly among CMR, PMR and DAL interventions (means = 54.5 ± 2.9, 54.7 ± 2.9 and 54.5 ± 2.5 min, respectively; p = 0.82). RPE and affective response were higher in DAL intervention (p < 0.01). Glucose, insulin, cortisol and creatine kinase responses showed no significant difference among interventions.

CONCLUSIONS

In a fed state, CMR has not caused metabolic changes, and it has not improved physical performance compared to ad libitum water intake, but demonstrated a possible central effect. ReBec registration number: RBR-4vpwkg. Available in http://www.ensaiosclinicos.gov.br/rg/?q=RBR-4vpwkg.

Strength, Affect Regulation, and Subcortical Morphology in Military Pilots

INTRODUCTION

Previous studies have shown links of body composition and fitness measures with brain structure, as well as with different aspects of emotional adjustment and well-being. However, the possible role of trait emotion-regulation success in the relationship between fitness/body composition and emotion-related subcortical structures has never been directly addressed.

METHODS

Twenty-three elite helicopter pilots were assessed in fat mass percentage, an endurance test to volitional exhaustion, bench-press power output, and negative urgency (trait affect regulation failure). Their brains were scanned using magnetic resonance imaging to estimate the size of the accumbens/amygdala, considered together, and the thalamus. Resulting correlations were used to test the relationship between body composition/fitness measures and brain structures' size, and the role of negative urgency therein, using structural equation modeling.

RESULTS

Fat mass percentage was associated with the size of the thalamus and the amygdala/accumbens. In the latter case, negative urgency and bench-press power output predicted structure size (and explained the effect of fat mass percentage away). In other words, bench-press power output and emotion regulation success (but not endurance performance) were associated with a larger amygdala/accumbens size.

CONCLUSIONS

Bench-press power output and emotion regulation success are independently associated with a larger amygdala/accumbens size, although present evidence does not allow for determination of causal directionality.

Effects of Three Commercially Available Sports Drinks on Substrate Metabolism and Subsequent Endurance Performance in a Postprandial State

Purpose: To examine the effects of commercially available sports beverages with various components on substrate metabolism and subsequent performance. Methods: Two studies were conducted in a double-blinded, counterbalanced manner. Study I was designed to determine the glycemic index, while study II determined the utilization of substrates and subsequent exercise performance. Ten healthy male participants (age 21.70 ± 2.41 years, height 176.60 ± 5.23 cm, weight 66.58 ± 5.38 kg, V̇O_2max 48.1 ± 8.4 mL/kg/min) participated in both study I and study II. Three types of commercially available sports beverage powders were used. The powders consisted primarily of oligosaccharides (low molecular weight carbohydrates, L-CHO), hydrolyzed starch (high molecular weight CHO, H-CHO), and whey protein powder with carbohydrate (CHO-PRO). They were dissolved in purified water with identical CHO concentration of 8% (w/v). In study I, each participant underwent two oral glucose tolerance tests (OGTT) and one glycemic response test for each sports drink. In study II, participants cycled for 60 min at 70% V̇O_2max, one hour after consuming a standardized breakfast. One of four prescribed beverages (L-CHO, H-CHO, CHO-PRO, and Placebo control, PLA) was served at 0, 15, 30, 45 min during the exercise. Six hours after the first exercise session, participants came back for a “time to exhaustion test” (TTE). Blood samples were drawn at 0, 30, and 60 min in the first exercise session, while arterial blood gas analysis was conducted at 0, 30, and 60 min in both sessions. Subjective feelings (rating of perceived exertion and abdominal discomfort) were also evaluated every 30 min during exercise. Results: Compared to the reference standardized glucose solution, the glycemic index of the L-CHO beverage was 117.70 ± 14.25, while H-CHO was 105.50 ± 12.82, and CHO-PRO was 67.23 ± 5.88. During the exercise test, the insulin level at 30 and 60 min was significantly lower than baseline following the treatment of L-CHO, H-CHO, and PLA (p < 0.05). The CHO oxidation rate at 60 min in the first exercise session was significantly higher than that at 60 min in the second exercise session following the L-CHO treatment (p < 0.05). Time to exhaustion was not significantly different (p > 0.05). Conclusion: The CHO sports beverage with additional PRO maintains insulin production during endurance cycling at 70% V̇O_2max in the postprandial state. L-CHO sports beverage suppresses fat utilization during the subsequent exercise performance test. The subsequent exercise performance (as evaluated by TTE) was not influenced by the type of CHO or the addition of PRO in the commercially available sports beverages used in the present study.

Effect of carbohydrate ingestion during cycling exercise on affective valence and activation in recreational exercisers

Carbohydrate (CHO) ingestion enhances "feel-good" responses during acute exercise but no study has examined the effect of regular ingestion of CHO on affective valence. We investigated the effect of CHO ingestion on perceptual responses and perceived work intensity of individual exercise sessions throughout a 10-week cycling ("spin") exercise intervention. We also assessed whether any changes in affect and/or perceived work intensity would influence health and fitness parameters. Twelve recreational exercisers (46 ± 9 years; nine females and three males) were randomly allocated to either CHO (7.5% CHO; 5 mL · kg^-1 per exercise session; n = 6; CHO) or placebo (0% CHO, taste- and volume-matched solution; n = 6; PLA) groups. Participants exercised 2 × 45-min per week, over a 10-week intervention period. Perceptual measures of exertion (RPE), affect (feeling scale, FS) and activation (felt arousal scale, FAS) were assessed after each exercise session. The FAS ratings increased over time in CHO but decreased throughout the intervention in PLA (P = 0.03). There were no differences in heart rate (P = 0.70), RPE (P = 0.05) and FS (P = 0.84) between trials. Furthermore, no changes in health and fitness parameters were observed over time or between groups. CHO ingestion enhanced ratings of activation in recreational exercisers throughout a 10-week cycling intervention.

Effect of mouth rinsing and ingestion of carbohydrate solutions on mood and perceptual responses during exercise

Background

The aim of this study was to investigate whether mouth rinsing or ingesting carbohydrate (CHO) solutions impact on perceptual responses during exercise.

Methods

Nine moderately trained male cyclists underwent a 90-min glycogen-reducing exercise, and consumed a low CHO meal, prior to completing an overnight fast. A 1-h cycle time trial was performed the following morning. Four trials, each separated by 7 days, were conducted in a randomized, counterbalanced study design: 15% CHO mouth rinse (CHOR), 7.5% CHO ingestion (CHOI), placebo mouth rinse (PLAR) and placebo ingestion (PLAI). Solution volumes (1.5 ml · kg⁻¹ ingestion trials and 0.33 ml · kg⁻¹ rinsing trials) were provided after every 12.5% of completed exercise. Perceptual scales were used to assess affective valence (feeling scale, FS), arousal (felt arousal scale, FAS), exertion (ratings of perceived exertion, RPE) and mood (profile of mood states, POMS) before, during and immediately after exercise.

Results

There was no difference in RPE (CHOI, 14.0 ± 1.9; CHOR, 14.2 ± 1.7; PLAI, 14.6 ± 1.8; PLAR, 14.6 ± 2.0; P = 0.35), FS (CHOI, 0.0 ± 1.7; CHOR, −0.2 ± 1.5; PLAI, −0.8 ± 1.4; PLAR, −0.8 ± 1.6; P = 0.15), or FAS (CHOI, 3.6 ± 1.1; CHOR, 3.5 ± 1.0; PLAI, 3.4 ± 1.4; PLAR, 3.3 ± 1.3; P = 0.725) scores between trials. While overall POMS score did not appear to differ between trials, the ‘vigour’ subscale indicated that CHOI may facilitate the maintenance of ‘vigour’ scores over time, in comparison to the steady decline witnessed in other trials (P = 0.04). There was no difference in time trial performance between trials (CHOI, 65.3 ± 4.8 min; CHOR, 68.4 ± 3.9 min; PLAI, 68.7 ± 5.3 min; PLAR, 68.3 ± 5.2 min; P = 0.21) but power output was higher in CHOI (231.0 ± 33.2 W) relative to other trials (221–223.6 W; P < 0.01).

Conclusions

In a CHO-reduced state, mouth rinsing with a CHO solution did not impact on perceptual responses during high-intensity exercise in trained cyclists and triathletes. On the other hand CHO ingestion improved perceived ratings of vigour and increased power output during exercise.

Perceptual Changes in Response to Two Regimens of Interval Training in Sedentary Women

This study examined acute and chronic changes in perceptual measures (rating of perceived exertion [RPE], affect, and arousal) in response to 2 regimens of high-intensity interval training (HIIT). Twenty-three healthy sedentary women (mean ± SD age and V[Combining Dot Above]O2max = 23.0 ± 5.7 years and 30.1 ± 4.4 ml·kg·min, respectively) were randomized to complete 12 weeks of one of 2 HIIT regimes, whereas an additional 7 women served as sedentary controls. Training was performed 3 days per week on a cycle ergometer and consisted of up to ten 1-minute bouts at moderate (60-80%Wmax = moderate intensity [MOD]) or more intense (80-90%Wmax = HI) workloads separated by active recovery. At baseline and every 3 weeks, RPE, affect, and arousal were measured during training using validated scales. Repeated measures analysis of variance was used to examine acute and chronic changes in these variables to HIIT. Data revealed significant (p < 0.001) increases in RPE and arousal and decreases (p < 0.001) in affect during acute HIIT, with RPE responses differing (p ≤ 0.05) between HI and MOD. However, acute changes in affect and arousal were similar in HI and MOD. Training led to a significant reduction in RPE, whereas both affect and arousal were unchanged (p > 0.05) after HIIT. Completion of moderate or more intense interval training reduces perceptions of RPE during training yet does not alter arousal or affect. RPE was reduced via training, yet large dependence on anaerobic metabolism during HIIT may minimize training-induced changes in affect.

Effects of an Injected Placebo on Endurance Running Performance

PURPOSE

This study aims to quantify the magnitude of the placebo effect of an injected placebo ("OxyRBX") purporting to have effects similar to those of recombinant human erythropoietin on endurance running performance in "real-world" field-based head-to-head competition settings.

METHODS

Fifteen endurance-trained club-level men (mean ± SD: age, 27.5 ± 6.8 yr; body mass index, 22.9 ± 2.0 kg·m) with 10-km personal-best record times of 39.3 ± 4.4 min completed a randomized cross-over study of 3-km races before and after 7-d "control" and "placebo" phases. During the placebo phase, participants self-administered subcutaneous saline injections daily, believing it to be OxyRBX, with no intervention during the control phase. At the start and end of each 7-d phase, 3-km running performance was assessed. Qualitative assessments of participants' perceptions and experiences were recorded throughout and during semistructured interviews on completion.

RESULTS

Race time improved significantly more in response to placebo intervention (9.73 ± 1.96 s faster, P = 0.0005) than in response to control (1.82 ± 1.94 s faster, P = 0.41; Pinteraction = 0.02). In response to placebo, participants reported reductions in physical effort, increased potential motivation, and improved recovery. Beliefs and congruence between positive expectations of the effects of placebo and perceptions of physical change during training also appeared to impact on competitive performance.

CONCLUSIONS

Compared to control, the injected placebo improved 3-km race time by 1.2%. This change is of clear sporting relevance but is smaller than the performance improvement elicited by recombinant human erythropoietin administration. Qualitative data suggest that placebo may have improved performance by both reducing perception of effort and increasing potential motivation, in accord with the psychobiological model for exercise performance, and that cognitive and noncognitive processes appear to have influenced placebo response.

The Effect of Breakfast Prior to Morning Exercise on Cognitive Performance, Mood and Appetite Later in the Day in Habitually Active Women

Pre-exercise nutritional practices for active females exercising for mood, cognitive and appetite benefits are not well established. Results from an initial field pilot study showed that higher energy intake at breakfast was associated with lower fatigue and higher overall mood and alertness post-exercise (all p < 0.05). In a follow-up, randomised, controlled trial, 24 active women completed three trials in a balanced, cross-over design. At 0815 h participants completed baseline cognitive tasks, mood and appetite visual analogue scales (VAS) and were administered a cereal breakfast (providing 118 or 236 kcal) or no breakfast. After 45 min, they completed a 30 min run at 65% heart rate reserve (HRR). Parameters were re-assessed immediately after exercise, then hourly until lunch (~1240 h), immediately post-lunch and at 1500 and 1900 h via a mobile phone. Breakfast enhanced feelings of relaxation before lunch (p < 0.05, d > 0.40), though breakfast was detrimental for working memory mid-afternoon (p = 0.019, d = 0.37) and mental fatigue and tension later in the day (all p < 0.05, d > 0.038). Breakfast was also beneficial for appetite control before lunch irrespective of size (all p < 0.05, d > 0.43). These data provide information on pre-exercise nutritional practices for active females and suggest that a small breakfast eaten prior to exercise can benefit post-exercise mood and subjective appetite ratings.

Effect of Galactose Ingestion Before and During Exercise on Substrate Oxidation, Postexercise Satiety, and Subsequent Energy Intake in Females

OBJECTIVE

To examine the effects of consuming a galactose carbohydrate (CHO) drink on substrate oxidation, postexercise satiety, and subsequent energy intake.

METHODS

Nine recreationally active eumenorrheic females undertook 3 trials, each consisting of running for 60 minutes at 65% VO(2peak) followed immediately by a 90-minute rest period. Prior to (300 ml) and at 15-minute intervals during exercise (150 ml), participants consumed either a glucose (GLU: GI 89) or galactose (GAL: GI 20) drink, each of which contained 45 g of CHO, or an artificially sweetened placebo (PLA). Following the rest period, participants were provided with an ad libitum test lunch and asked to record food intake for the remainder of the day.

RESULTS

Plasma glucose was significantly greater throughout exercise and rest following the GLU trial compared with the GAL and PLA trials (P < 0.05); however there were no differences in CHO oxidation. Hunger was significantly lower (P < 0.05) throughout the GAL compared to the GLU and PLA trials. There were no significant differences between trials for energy intake during the postexercise meal. Overall net energy balance for the 24 hours was negative in both the GAL (-162 ± 115 kcal; P < 0.05 vs GLU) and PLA trials (-49 ± 160 kcal).

CONCLUSIONS

Results demonstrate that ingesting a solution containing GAL before and during exercise can positively impact postexercise satiety and energy balance throughout the day, compared to a more readily available and widely consumed form of CHO. Despite this, there appears to be no apparent benefit in consuming a CHO beverage on fuel utilization for this moderate exercise intensity and duration.

Non-conscious visual cues related to affect and action alter perception of effort and endurance performance

The psychobiological model of endurance performance proposes that endurance performance is determined by a decision-making process based on perception of effort and potential motivation. Recent research has reported that effort-based decision-making during cognitive tasks can be altered by non-conscious visual cues relating to affect and action. The effects of these non-conscious visual cues on effort and performance during physical tasks are however unknown. We report two experiments investigating the effects of subliminal priming with visual cues related to affect and action on perception of effort and endurance performance. In Experiment 1 thirteen individuals were subliminally primed with happy or sad faces as they cycled to exhaustion in a counterbalanced and randomized crossover design. A paired t-test (happy vs. sad faces) revealed that individuals cycled significantly longer (178 s, p = 0.04) when subliminally primed with happy faces. A 2 × 5 (condition × iso-time) ANOVA also revealed a significant main effect of condition on rating of perceived exertion (RPE) during the time to exhaustion (TTE) test with lower RPE when subjects were subliminally primed with happy faces (p = 0.04). In Experiment 2, a single-subject randomization tests design found that subliminal priming with action words facilitated a significantly longer TTE (399 s, p = 0.04) in comparison to inaction words. Like Experiment 1, this greater TTE was accompanied by a significantly lower RPE (p = 0.03). These experiments are the first to show that subliminal visual cues relating to affect and action can alter perception of effort and endurance performance. Non-conscious visual cues may therefore influence the effort-based decision-making process that is proposed to determine endurance performance. Accordingly, the findings raise notable implications for individuals who may encounter such visual cues during endurance competitions, training, or health related exercise.

Prediction of performance reduction in self-paced exercise as modulated by the rating of perceived exertion

PURPOSE

Rating of perceived exertion (RPE) is a scale of exercise difficulty and has been hypothesized to be a regulator of work rate during self-pacing. The goal of this work was to develop a dynamic prediction of RPE and to characterize the control strategy employed to reduce work rate during self-paced exercise using RPE as feedback.

METHODS

Training and test data were acquired from the literature to develop a linear regression of RPE as a function of four physiological variables: core temperature, mean-weighted skin temperature, metabolic rate, and integral of relative oxygen consumption (R (2) = 0.85). A thermoregulatory model was used to predict core and mean-weighted skin temperature. Utilizing self-paced cycling and running data from the literature, we characterized reductions in work rate with a proportional-derivative control algorithm with RPE as feedback.

RESULTS

Bland-Altman analysis revealed the necessity to parameterize RPE equations for untrained and endurance-trained individuals. Afterwards, dynamic predictions of RPE were accurate for a wide range of activity levels and air temperatures for walking, running, and cycling (LoA and bias of 2.3 and -0.03, respectively). For self-paced exercise, the control algorithm characterized the trend and magnitude of work rate reductions for cycling and running, and showed regulated RPE to be less conservative for shorter vs. longer duration exercise.

CONCLUSIONS

A novel methodology to characterize self-paced work intensity, based upon dynamic physiologic response, is provided. The complete model is a useful tool that estimates performance decrements during self-paced exercise and predicts tolerance time for exhaustive fixed-rate exercise.

Talking yourself out of exhaustion: the effects of self-talk on endurance performance

PURPOSE

The psychobiological model of endurance performance proposes that the perception of effort is the ultimate determinant of endurance performance. Therefore, any physiological or psychological factor affecting the perception of effort will affect endurance performance. Accordingly, this novel study investigated the effects of a frequently used psychological strategy, motivational self-talk (ST), on RPE and endurance performance.

METHODS

In a randomized between-group pretest-posttest design, 24 participants (mean ± SD age = 24.6 ± 7.5 yr, VO2max = 52.3 ± 8.7 mL·kg·min) performed two constant-load (80% peak power output) cycling time-to-exhaustion (TTE) tests, punctuated by a 2-wk ST intervention or a control phase.

RESULTS

A group (ST vs Control) × test (pretest vs posttest) mixed-model ANOVA revealed that ST significantly enhanced TTE test from pretest to posttest (637 ± 210 vs 750 ± 295 s, P < 0.05) with no change in the control group (486 ± 157 vs 474 ± 169 s). Moreover, a group × test × isotime (0%, 50%, and 100%) mixed-model ANOVA revealed a significant interaction for RPE, with follow-up tests showing that motivational self-talk significantly reduced RPE at 50% isotime (7.3 ± 0.6 vs 6.4 ± 0.8, P < 0.05), with no significant difference in the control group (6.9 ± 1.9 vs 7.0 ± 1.7).

CONCLUSIONS

This study is the first to demonstrate that ST significantly reduces RPE and enhances endurance performance. The findings support the psychobiological model of endurance performance and illustrate that psychobiological interventions designed to specifically target favorable changes in the perception of effort are beneficial to endurance performance. Consequently, this psychobiological model offers an important and novel perspective for future research investigations.

The Effect of Acute Rhodiola rosea Ingestion on Exercise Heart Rate, Substrate Utilisation, Mood State, and Perceptions of Exertion, Arousal, and Pleasure/Displeasure in Active Men

The aim of this study was to examine the effect of acute Rhodiola rosea (R. rosea) ingestion on substrate utilisation, mood state, RPE, and exercise affect. Ten males (mean age ± S.D. = 26 ± 6 years) completed two 30-minute cycling trials at an intensity of 70% of [Formula: see text] following ingestion of either 3 mg·kg(-1) body mass of R. rosea or placebo using a double-blind, crossover design. During exercise, heart rate and RPE were recorded. Participants completed measures of mood state and exercise affect before and after exercise. Expired air samples were taken during exercise to determine substrate utilisation. Repeated measures analysis of variance indicated that RPE was significantly lower at 30 minutes into exercise versus placebo (P = 0.003). Perceptions of arousal (P = 0.05) and pleasure were significantly higher after exercise with R. rosea compared to placebo (P = 0.003). Mood state scores for vigor were also higher in R. rosea condition compared to placebo (P = 0.008). There were no significant differences in energy expenditure, carbohydrate, or fat oxidation between conditions (P > 0.05). Ingestion of R. rosea favourably influenced RPE and exercise affect without changes in energy expenditure or substrate utilization during 30-minute submaximal cycling performance.

Influence of Affective Changes on Behavioral and Cognitive Performances After Acute Bout of Exhaustive Exercise

The present study was conducted to evaluate the influence of acute, exhaustive, exercise on affective responses (affective valence and activation) and behavioral and cognitive performances in medical students using circumplex model, reaction time (RT), and P300, respectively. Twelve healthy, untrained, male medical students participated in self-controlled, counterbalanced trial conducted over two sessions: baseline and exercise. In the baseline session, recordings of auditory reaction time (ART), visual RT (VRT), and P300 latency and amplitude (using acoustic “oddball” paradigm) were taken at the end of 15 min seated rest. Exercise session comprised of continuous maximal graded incremental exercise until volitional exhaustion, on a computer-based motorized treadmill and recordings done after heart rate returned to within +10% of pre-exercise values. Perceived exertion, affective valence, and activation were assessed pre-exercise, during (30 s before the end of each stage), and post-exercise (immediately, 5 and 10 min after) by Borg’s scale, feeling scale (FS), and felt-arousal scale (FAS), respectively. There was marked variability in individual affective responses to a single bout of exhaustive exercise with few subjects showing activated pleasure (Energetic Arousal) and others showing activated displeasure (Tense arousal). The results further indicated an overall improvement in behavioral (as evidenced by the decrease in ART and VRT) and cognitive performances (as evidenced by increase in the P300 amplitude and decrease in the P300 latency) in medical students in the exercise session relative to the baseline session despite bidirectional shifts in valence suggesting that interdependent neural systems might mediate these effects.

Can carbohydrate mouth rinse improve performance during exercise? A systematic review

The purpose of this review was to identify studies that have investigated the effect of carbohydrate (CHO) mouth rinse on exercise performance, and to quantify the overall mean difference of this type of manipulation across the studies. The main mechanisms involving the potential benefit of CHO mouth rinse on performance was also explored. A systematic review was conducted in the following electronic databases: PubMed, SciELO, Science Direct, MEDLINE, and the Cochrane Library (Cochrane Central Register of Controlled Trials), without limit of searches. Eleven studies were classified as appropriate and their results were summarized and compared. In nine of them, CHO mouth rinse increased the performance (range from 1.50% to 11.59%) during moderate- to high-intensity exercise (~75% Wmax or 65% VO₂max, ~1 h duration). A statistical analysis to quantify the individual and overall mean differences was performed in seven of the 11 eligible studies that reported power output (watts, W) as the main performance outcome. The overall mean difference was calculated using a random-effect model that accounts for true variation in effects occurring in each study, as well as random error within a single study. The overall effect of CHO mouth rinse on performance was significant (mean difference = 5.05 W, 95% CI 0.90 to 9.2 W, z = 2.39, p = 0.02) but there was a large heterogeneity between the studies (I² = 52%). An activation of the oral receptors and consequently brain areas involved with reward (insula/operculum frontal, orbitofrontal cortex, and striatum) is suggested as a possible physiological mechanism responsible for the improved performance with CHO mouth rinse. However, this positive effect seems to be accentuated when muscle and liver glycogen stores are reduced, possibly due to a greater sensitivity of the oral receptors, and require further investigation. Differences in duration of fasting before the trial, duration of mouth rinse, type of activity, exercise protocols, and sample size may account for the large variability between the studies.

Psychological need satisfaction, intrinsic motivation and affective response to exercise in adolescents

OBJECTIVES

To further understanding of the factors influencing adolescents' motivations for physical activity, the relationship of variables derived from Self-Determination Theory to adolescents' affective response to exercise was examined.

DESIGN

Correlational.

METHOD

Adolescents (N = 182) self-reported psychological needs satisfaction (perceived competence, relatedness, and autonomy) and intrinsic motivation related to exercise. In two clinic visits, adolescents reported their affect before, during, and after a moderate-intensity and a hard-intensity exercise task.

RESULTS

Affective response to exercise and psychological needs satisfaction independently contributed to the prediction of intrinsic motivation in hierarchical linear regression models. The association between affective response to exercise and intrinsic motivation was partially mediated by psychological needs satisfaction.

CONCLUSIONS

Intrinsic motivation for exercise among adolescents may be enhanced when the environment supports perceived competence, relatedness, and autonomy, and when adolescents participate in activities that they find enjoyable.

The differential effects of a complex protein drink versus isocaloric carbohydrate drink on performance indices following high-intensity resistance training: a two arm crossover design

Background

Post-workout nutrient timing and macronutrient selection are essential for recovery, glycogen replenishment and muscle protein synthesis (MPS). Performance repeatability, particularly after strenuous activity, can be influenced by substrate availability, recovery markers and perceived rate of exertion. This study compared the differential effects of a complex protein ready-to-drink beverage (VPX) and isocaloric carbohydrate beverage (iCHO) on performance—agility T-test, push-up test, 40-yard sprint, and rate of perceived exertion (RPE), following high-intensity resistance training (HIRT).

Methods

In a randomized, double blind two-arm crossover controlled trial, 15 subjects performed a 15–18 minute (2:1 work to rest) HIRT and then immediately drank one of the two treatments. After a 2-hour fast, subjects returned to execute the field tests and report RPE. The protocol was repeated one week later with the other treatment.

Results

There were no significant main effect differences in the agility T-test (p = 0.83), push-up (p = 0.21) sprint (p = 0.12), average agility RPE (p = 0.83), average push-up RPE (p = 0.81) or average sprint RPE (p = 0.66) between the two trials and the two treatments. The multivariate analysis yielded a cumulative significant interaction effect amongst the three performance variables after consuming VPX (p < 0.01). These results suggest a complex protein beverage is a better post-workout choice compared to an isocaloric carbohydrate beverage for repeated performance for activities that require multiple energy demands and athletic skills; however, this outcome was not observed for each single performance event or RPE.

Conclusion

When considering the collective physical effects of the agility T-test, push-up and sprint tests, a complex protein beverage may provide a recovery advantage as it relates to repeated-bout performance compared to an iCHO-only beverage. Additional research examining the chronic effects of post-exercise protein versus iCHO beverages on performance repeatability, particularly in special populations (e.g. tactical and elite athletes), is warranted to further develop these findings.

Post-prandial carbohydrate ingestion during 1-h of moderate-intensity, intermittent cycling does not improve mood, perceived exertion, or subsequent power output in recreationally-active exercisers

BACKGROUND

This study compared the effects of ingesting water (W), a flavored carbohydrate-electrolyte (CE) or a flavored non-caloric electrolyte (NCE) beverage on mood, ratings of perceived exertion (RPE), and sprint power during cycling in recreational exercisers.

METHODS

Men (n = 23) and women (n = 13) consumed a 24-h standardized diet and reported 2-4 h post-prandial for all test sessions. After a familiarization session, participants completed 50 min of stationary cycling in a warm environment (wet bulb globe temperature = 25.0°C) at ~ 60-65% of heart rate reserve (146 ± 4 bpm) interspersed with 5 rest periods of 2 min each. During exercise, participants consumed W, CE, or NCE, served in a counterbalanced cross-over design. Beverage volume was served in 3 aliquots equaling each individual's sweat losses (mean 847 ± 368 mL) during the familiarization session. Profiles of Mood States questionnaires (POMS) were administered and blood glucose levels were determined pre- and post- sub-maximal cycling. Following sub-maximal exercise, participants completed 3 30-s Wingate anaerobic tests (WAnT) with 2.5 min rest between tests to assess performance.

RESULTS

Blood glucose was higher (p <  0.05) after 50 min of submaximal cycling just prior to the WAnT for CE (6.1 ± 1.7 mmol/L) compared to W (4.9 ± 1.5 mmol/L) and NCE (4.6 ± 1.2 mmol/L). Nonetheless, there were no differences among treatments in peak (642 ± 153, 635 ± 143, 650 ± 141 watts for W, NCE, and CE, respectively; p  =  0.44) or mean (455 ± 100, 458 ± 95, 454 ± 95 watts for W, NCE, and CE, respectively; p = 0.62) power for the first WAnT or mean (414 ± 92, 425 ± 85, 423 ± 82 watts, respectively; p = 0.13) power output averaged across all 3 WAnT. Likewise, RPE during submaximal exercise, session RPE, and fatigue and vigor assessed by POMS did not differ among beverage treatments (p > 0.05).

CONCLUSIONS

Carbohydrate ingestion consumed by recreational exercisers during a 1-h, moderate-intensity aerobic workout did not alter mood or perceived exertion, nor did it affect subsequent anaerobic performance under the conditions of this study. Drinking caloric sport beverages does not benefit recreational exercisers in a non-fasted state.

Influence of fluid intake on soccer performance in a temperate environment

The study aim was to examine the effect of fluid intake and dehydration on soccer-skill and high-intensity, intermittent-running performance after 90-minutes intermittent exercise (Loughborough Intermittent Shuttle Test). Thirteen semi-professional, men soccer-players completed, the 90-minute intermittent exercise on three fluid trials: prescribed fluid equal to sweat loss (1.65 ± 0.17 litres: Mean ± s), ad libitum fluid (0.85 ± 0.19 litres) and no fluid. After the intermittent exercise, dehydration was equivalent to 0.3 ± 0.1, 1.1 ± 0.2, 2.5 ± 0.4% body mass loss on the prescribed-fluid, ad libitum-fluid and no-fluid trials, respectively. Soccer-skill and high-intensity, intermittent-running performance, as assessed by the Loughborough Soccer Passing and Shooting Tests, and the Yo-Yo Intermittent Recovery Test, declined after the intermittent exercise compared with assessments made before. The decline in performance was however similar on all fluid trials (P > 0.34 for interactions and effect sizes were trivial or small). These effect sizes suggest larger fluid intakes had limited and inconsistent (both beneficial and detrimental) effects on performance. In conclusion the results suggest that fluid intake during 90-minutes of intermittent exercise and modest dehydration have limited and inconsistent effects on soccer passing and shooting skill or high-intensity, intermittent-running in a temperate environment.

Effect of mouth-rinsing carbohydrate solutions on endurance performance

Ingesting carbohydrate-electrolyte solutions during exercise has been reported to benefit self-paced time-trial performance. The mechanism responsible for this ergogenic effect is unclear. For example, during short duration (≤1 hour), intense (>70% maximal oxygen consumption) exercise, euglycaemia is rarely challenged and adequate muscle glycogen remains at the cessation of exercise. The absence of a clear metabolic explanation has led authors to speculate that ingesting carbohydrate solutions during exercise may have a 'non-metabolic' or 'central effect' on endurance performance. This hypothesis has been explored by studies investigating the performance responses of subjects when carbohydrate solutions are mouth rinsed during exercise. The solution is expectorated before ingestion, thus removing the provision of carbohydrate to the peripheral circulation. Studies using this method have reported that simply having carbohydrate in the mouth is associated with improvements in endurance performance. However, the performance response appears to be dependent upon the pre-exercise nutritional status of the subject. Furthermore, the ability to identify a central effect of a carbohydrate mouth rinse maybe affected by the protocol used to assess its impact on performance. Studies using functional MRI and transcranial stimulation have provided evidence that carbohydrate in the mouth stimulates reward centres in the brain and increases corticomotor excitability, respectively. However, further research is needed to determine whether the central effects of mouth-rinsing carbohydrates, which have been seen at rest and during fatiguing exercise, are responsible for improved endurance performance.

Caffeine ingestion, affect and perceived exertion during prolonged cycling

Caffeine's metabolic and performance effects have been widely reported. However, caffeine's effects on affective states during prolonged exercise are unknown. Therefore, this was examined in the present study. Following an overnight fast and in a randomised, double-blind, counterbalanced design, twelve endurance trained male cyclists performed 90 min of exercise at 70% VO(₂ max) 1h after ingesting 6 mg kg⁻¹ BM of caffeine (CAF) or placebo (PLA). Dimensions of affect and perceived exertion were assessed at regular intervals. During exercise, pleasure ratings were better maintained (F(₃,₃₈)=4.99, P < 0.05) in the CAF trial compared to the PLA trial with significantly higher ratings at 15, 30 and 75 min (all P < 0.05). Perceived exertion increased (F(₃,₃₈) = 19.86, P < 0.01) throughout exercise and values, overall, were significantly lower (F(₁,₁₁) = 9.26, P < 0.05) in the CAF trial compared to the PLA trial. Perceived arousal was elevated during exercise but did not differ between trials. Overall, the results suggest that a moderate dose of CAF ingested 1h prior to exercise maintains a more positive subjective experience during prolonged cycling. This observation may partially explain caffeine's ergogenic effects.

Branched-chain amino acid supplementation lowers perceived exertion but does not affect performance in untrained males

The purpose of this study was to determine whether branched-chain amino acid (BCAA) supplementation affects aerobic performance, ratings of perceived exertion (RPE), or substrate utilization as compared with an isocaloric, carbohydrate (CHO) beverage or a noncaloric placebo (PLAC) beverage. Nine untrained males performed three 90-minute cycling bouts at 55% VO₂ peak followed by 15-minute time trials. Subjects, who were blinded to beverage selection, ingested a total of 200 kcal via the CHO or BCAA beverage before and at 60 minutes of exercise or the PLAC beverage on the same time course. RPE and metabolic measurements were taken every 15 minutes during steady-state exercise, and each of the trials was separated by 8 weeks. Plasma glucose and BCAA concentrations were measured pre- and post-exercise. A greater distance (4.6 ± 0.6 km) was traveled in the time-trial during the CHO trial than the PLAC trial (3.9 ± 0.4 km) (p < 0.05). There was no difference between the BCAA (4.4 ± 0.5 km) and PLAC trials. RPE was reduced at the 75-minute and 90-minute mark during the BCAA trial as compared with the PLAC trial. There were no significant differences found for the trial vs. time interaction in regard to respiratory exchange ratio. Thus, CHO supplementation improves performance in a loaded time-trial as compared with a PLAC beverage. BCAA supplementation, although effective at increasing blood concentrations of BCAA, did not influence aerobic performance but did attenuate RPE as compared with a PLAC beverage.

Influence of ingesting a carbohydrate-electrolyte solution before and during a 1-hour run in fed endurance-trained runners

The aim of this study was to determine whether the ingestion of a carbohydrate-electrolyte solution would improve 1-h running performance in runners who had consumed a meal 3 h before exercise. Ten endurance-trained male runners completed two trials that required them to run as far as possible in 1 h on an automated treadmill that allowed changes in running speed without manual input. Following the consumption of the pre-exercise meal, which provided 2.5 g carbohydrate per kilogram body mass (BM), runners ingested either a 6.4% carbohydrate-electrolyte solution or placebo solution (i.e. 8 ml x kg BM(-1)) 30 min before and 2 ml x kg BM(-1) at 15-min intervals throughout the 1-h run. There were no differences in total distance covered (placebo: 13,680 m, s = 1525; carbohydrate: 13,589 m, s = 1635) (P > 0.05). Blood glucose and lactate concentration, respiratory exchange ratio, and carbohydrate oxidation during exercise were not different between trials (P > 0.05). There were also no differences in ratings of perceived exertion, felt arousal or pleasure-displeasure between trials (P > 0.05). In conclusion, the ingestion of a 6.4% carbohydrate-electrolyte solution did not improve 1-h running performance when a high carbohydrate meal was consumed 3 h before exercise.