Carbohydrate-electrolyte Solution Research Articles

The Roles of Carbohydrate-Electrolyte Solutions in Athlete Hydration Status and Performance : A Narrative Review

The Roles of Carbohydrate-Electrolyte Solutions in Athlete Hydration Status and Performance : A Narrative Review

Oral rehydration beverages for treating exercise-associated dehydration: a systematic review.Part I: carbohydrate-electrolyte solutions.

Exercise-associated dehydration is a common problem, especially at sporting events. Although there are recommendations to drink a certain volume per kg body mass lost after exercise, there is no clear guidance about the type of rehydration beverage. The aim of this systematic review is to assess the effectiveness of carbohydrate-electrolyte solutions as a rehydration solution for exercise-associated dehydration. Medline (via the PubMed interface), Embase and the Cochrane Library were searched for relevant studies. The search is up to date until June 2022. Controlled trials involving adults and children were included if dehydration was the result of physical exercise and if drinking carbohydrate-electrolyte solutions, of any percentage carbohydrate, was compared with drinking water. All languages were included as long as an English abstract was available. Data on study design, study population, interventions, outcome measures and study limitations were extracted from each included article. Certainty was assessed using GRADE. Out of 3485 screened articles, 19 studies were included that assessed carbohydrate-electrolyte solutions (0% - 9% carbohydrate) compared with water. Although there is variability amongst the identified studies, drinking 0-3.9% and, especially, 4-9% carbohydrate-electrolyte (CE) solution may be effective for rehydration. A potential beneficial effect of drinking CE drinks compared with water was seen for many of the reviewed outcomes. Commercial CE drinks (ideally 4-9% CE drinks or alternatively 0-3.9% CE drinks) could be suggested for rehydration in persons with exercise associated dehydration when whole foods are not available.

Compositional Aspects of Beverages Designed to Promote Hydration Before, During, and After Exercise: Concepts Revisited.

Hypohydration can impair aerobic performance and deteriorate cognitive function during exercise. To minimize hypohydration, athletes are recommended to commence exercise at least euhydrated, ingest fluids containing sodium during long-duration and/or high-intensity exercise to prevent body mass loss over 2% and maintain elevated plasma osmolality, and rapidly restore and retain fluid and electrolyte homeostasis before a second exercise session. To achieve these goals, the compositions of the fluids consumed are key; however, it remains unclear what can be considered an optimal formulation for a hydration beverage in different settings. While carbohydrate-electrolyte solutions such as sports drinks have been extensively explored as a source of carbohydrates to meet fuel demands during intense and long-duration exercise, these formulas might not be ideal in situations where fluid and electrolyte balance is impaired, such as practicing exercise in the heat. Alternately, hypotonic compositions consisting of moderate to high levels of electrolytes (i.e., ≥45 mmol/L), mainly sodium, combined with low amounts of carbohydrates (i.e., <6%) might be useful to accelerate intestinal water absorption, maintain plasma volume and osmolality during exercise, and improve fluid retention during recovery. Future studies should compare hypotonic formulas and sports drinks in different exercise settings, evaluating different levels of sodium and/or other electrolytes, blends of carbohydrates, and novel ingredients for addressing hydration and rehydration before, during, and after exercise.

Isolate Whey Protein Promotes Fluid Balance and Endurance Capacity Better Than Isolate Casein and Carbohydrate-Electrolyte Solution in a Warm, Humid Environment.

Protein ingestion is known to enhance post-exercise hydration. Whether the type of protein (i.e., whey, casein) can alter this response is unknown. Accordingly, this study aimed to compare the effects of the addition of milk-derived whey isolate or casein protein to carbohydrate-electrolyte (CE) drinks on post-exercise rehydration and endurance capacity. Thirty male soldiers (age: 24 ± 2.1 y; VO2max: 49.3 ± 4.7 mL/kg/min) were recruited. Upon losing ~2.2% of body mass by running in warm and humid conditions (32.3 °C, 76% relative humidity [RH]), participants ingested either a CE solution (66 g/L carbohydrate [CHO]), or CE plus isolate whey protein (CEW, 44 g/L CHO, 22 g/L isolate whey), or CE plus isolate casein protein (CEC, 44 g/L CHO, 22 g/L isolate casein) beverage in a volume equal to 150% of body mass loss. At the end of the 3 h rehydration period, a positive fluid balance was higher with CEW (0.22 L) compared to CEC (0.19 L) and CE (0.12 L). Overall mean fluid retention was higher in CEW (80.35%) compared with the CE (76.67%) and CEC trials (78.65%). The time of the endurance capacity test [Cooper 2.4 km (1.5 miles) run test] was significantly higher in CEC (14.25 ± 1.58 min) and CE [(12.90 ± 1.01 min; (p = 0.035)] than in CEW [(11.40 ± 1.41 min); (p = 0.001)]. The findings of this study indicate that the inclusion of isolate whey protein in a CE solution yields superior outcomes in terms of rehydration and enhanced endurance capacity, as compared to consuming the CE solution alone or in conjunction with isolate casein protein.

Effectiveness of an Isotonic Carbohydrate-Electrolyte Sports Beverage in Preventing Hypokalemia and Hyponatremia Among Patients Undergoing Colonoscopy: A Pilot Study

Colonoscopy is the gold standard for imaging the colonic mucosa to identify lesions for excision biopsy. For a colonoscopy to be successful, a thorough bowel cleansing is necessary; however, it can result to electrolyte imbalances. Co-administration of carbohydrate-electrolyte solutions may help prevent such complications. This study evaluated the effectiveness of an isotonic carbohydrate-electrolyte sports beverage in preventing hypokalemia and hyponatremia, when given for fluid replacement during bowel preparation for colonoscopy. This pilot study was conducted in a tertiary hospital for 6 months after approval from the Ethics Review Committee. Patients scheduled for elective colonoscopy were included. Two tablets of Bisacodyl 5mg/tablet per orem, followed by 1 tablespoon of phosphosoda dissolved in 1L Sprite was used for bowel preparation in both groups. Patients with normal baseline sodium and potassium were included. Group A patients were given the sports beverage while Group B patients were given distilled water. The post-bowel preparation serum sodium and potassium of the two groups were compared. For the Sports Beverage Group, both the serum sodium and potassium increased from baseline in 60% of patients, respectively. For the Distilled Water Group, the serum sodium decreased in 70% of patients and the serum potassium also decreased in 80% of patients after bowel preparation. For the Sports Beverage Group, 100% had normal sodium and 10% had hypokalemia while for the Distilled Water Group, 10% had hyponatremia and 40% had hypokalemia. None of the patients developed hypernatremia and hyperkalemia in both groups. The mean serum sodium between the two groups after bowel preparation was not statistically significant (p-value=0.531 vs 0.425). For the serum potassium, the mean values of the two groups after bowel preparation was statistically significant (p-value=0.044). Co-administration of an isotonic carbohydrate-electrolyte sports beverage is effective in preventing hypokalemia among patients undergoing bowel preparation for colonoscopy.

THE EFFECT OF COCONUT WATER INGESTION ON INTERMITTENT RUNNING EXERCISE PERFORMANCE

This research investigated the effects of coconut (COC) water ingestion during exhaustive intermittent running exercise performance. On separated two trials, 12 recreational male athletes (age 20 ± 2 years, body mass 59.9 ± 5.9 kg, fat percentage 11.8 ± 5.4%) completed a Yo-Yo Intermittent Recovery Test-Level 1 (Yo-yo IRT-1), running to exhaustion in a randomised counterbalanced order. The subjects were given 4 mL. kg-1 of either COC or carbohydrate-electrolyte (CHO-e) solution to be ingested prior to exercise. The distance covered, level of exhaustion, heart rate (HR), blood glucose, rating of perceived exertion (RPE), perceived arousal scale (FAS), and gastrointestinal discomfort (GI) were recorded intermittently during each trial. The distance covered with COC did not differ significantly from those data with CHO-e (CHO: 1066.7 ± 449.4 m; CHO-e:1106.7 ± 554.9 m, p = 0.85). There were also no significant differences in HR, RPE and FAS GI comfort between the trials (all p &gt; 0.05) expect for GI (p&lt; 0.05). The blood glucose was increased at the exhaustion of exercise, although, no significant difference was observed between the trials (p &gt; 0.05). Ingesting COC provided no ergogenic benefits during intermittent running exercise compared to CHO-e. The result of the current study suggests that COC ingestion and CHO-e were incapable of reducing perceive exercise intensity during the trials.

Effect of Carbohydrate-Electrolyte Solution Including Bicarbonate Ion Ad Libitum Ingestion on Urine Bicarbonate Retention during Mountain Trekking: A Randomized, Controlled Pilot Study.

We investigated whether bicarbonate ion (HCO3−) in a carbohydrate-electrolyte solution (CE+HCO3) ingested during climbing to 3000 m on Mount Fuji could increase urine HCO3− retention. This study was a randomized, controlled pilot study. Sixteen healthy lowlander adults were divided into two groups (six males and two females for each): a tap water (TW) group (0 kcal with no energy) and a CE+HCO3 group. The allocation to TW or CE+HCO3 was double blind. The CE solution contains 10 kcal energy, including Na+ (115 mg), K+ (78 mg), HCO3− (51 mg) per 100 mL. After collecting baseline urine and measuring body weight, participants started climbing while energy expenditure (EE) and heart rate (HR) were recorded every min with a portable calorimeter. After reaching a hut at approximately 3000 m, we collected urine and measured body weight again. The HCO3− balance during climbing, measured by subtracting the amount of urine excreted from the amount of fluid ingested, was −0.37 ± 0.77 mmol in the CE+HCO3, which was significantly higher than in the TW (−2.23 ± 0.96 mmol, p < 0.001). These results indicate that CE containing HCO3− supplementation may increase the bicarbonate buffering system during mountain trekking up to ~3000 m, suggesting a useful solution, at least, in the population of the present study on Mount Fuji.

Efficacy of ice slurry and carbohydrate-electrolyte solutions for firefighters.

ObjectivesTo examine the thermoregulatory and fluid‐electrolyte responses of firefighters ingesting ice slurry and carbohydrate–electrolyte solutions before and after firefighting operations.MethodsTwelve volunteer firefighters put on fireproof clothing and ingested 5 g/kg of beverage in an anteroom at 25°C and 50% relative humidity (RH; pre‐ingestion), and then performed 30 minutes of exercise on a cycle ergometer (at 125 W for 10 minutes and then 75 W for 20 minutes) in a room at 35℃ and 50% RH. The participants then returned to the anteroom, removed their fireproof clothing, ingested 20 g/kg of beverage (post‐ingestion), and rested for 90 minutes. Three combinations of pre‐ingestion and post‐ingestion beverages were provided: a 25℃ carbohydrate–electrolyte solution for both (CH condition); 25℃ water for both (W condition); and a −1.7℃ ice slurry pre‐exercise and 25℃ carbohydrate–electrolyte solution post‐exercise (ICE condition).ResultsThe elevation of body temperature during exercise was lower in the ICE condition than in the other conditions. The sweat volume during exercise was lower in the ICE condition than in the other conditions. The serum sodium concentration and serum osmolality were lower in the W condition than in the CH condition.ConclusionsThe ingestion of ice slurry while firefighters were wearing fireproof clothing before exercise suppressed the elevation of body temperature during exercise. Moreover, the ingestion of carbohydrate–electrolyte solution by firefighters after exercise was useful for recovery from dehydration.

Influence of Fluid Delivery Schedule and Composition on Fluid Balance, Physiologic Strain, and Substrate Use in the Heat

Wildfire suppression is characterized by high total energy expenditure and water turnover rates. Hydration position stands outline hourly fluid intake rates. However, dose interval remains ambiguous. We aimed to determine the effects of microdosing and bolus-dosing water and microdosing and bolus-dosing carbohydrate-electrolyte solutions on fluid balance, heat stress (physiologic strain index [PSI]), and carbohydrate oxidation during extended thermal exercise. In a repeated-measures cross-over design, subjects completed four 120-min treadmill trials (1.3 m·s-1, 5% grade, 33°C, 30% relative humidity) wearing a US Forest Service wildland firefighter uniform and a 15-kg pack. Fluid delivery approximated losses calculated from a pre-experiment familiarization trial, providing 22 doses·h-1 or 1 dose·h-1 (46±11, 1005±245 mL·dose-1). Body weight (pre- and postexercise) and urine volume (pre-, during, and postexercise) were recorded. Heart rate, rectal temperature, skin temperature, and steady-state expired air samples were recorded throughout exercise. Statistical significance (P<0.05) was determined via repeated-measures analysis of variance. Total body weight loss (n=11, -0.6±0.3 kg, P>0.05) and cumulative urine output (n=11, 677±440 mL, P>0.05) were not different across trials. The micro-dosed carbohydrate-electrolyte trial sweat rate was lower than that of the bolus-dosed carbohydrate-electrolyte, bolus-dosed water, and microdosed water trials (n=11, 0.8±0.2, 0.9±0.2, 0.9±0.2, 0.9±0.2 L·h-1, respectively; P<0.05). PSI was lower at 60 than 120 min (n=12, 3.6±0.7 and 4.5±0.9, respectively; P<0.05), with no differences across trials. The carbohydrate-electrolyte trial's carbohydrate oxidation was higher than water trial's (n=12, 1.5±0.3 and 0.8±0.2 g·min-1, respectively; P<0.05), with no dosing style differences. Equal-volume diverse fluid delivery schedules did not affect fluid balance, PSI, or carbohydrate oxidation during extended thermal work.

Effects Of Carbohydrate-Electrolyte Solution Supplementation On Fluid Retention And Aerobic Capacity After Exhaustive Exercise

Rehydration, or restoration of fluid spaces, is important when exhaustive endurance exercise (EEE) has compromised hydration status. Previous studies only investigated the effects of carbohydrate-electrolyte solution (CE) supplementation to facilitate replacement after exercise induced dehydration. CE supplementation for 1 hour before and 1 hour after EEE may play an important role in fluid retention and enhancing aerobic capacity. PURPOSE: To examine the effects of CE supplementation on fluid retention and aerobic capacity after EEE. METHODS: In a double-blind, crossover and counterbalanced designed study, nineteen health male participants were asked to intake ORS-SH@, an oral rehydration solution, (150 mL four times within an hour) or placebo (water) for 1 hour before and 1 hour after EEE. All participants completed graded exercise test to exhaustion on treadmill for determination of maximal oxygen consumption (VO2max) before supplementation, and then completed the exhaustive endurance exercise test at the intensity of 70% VO2max for 60 min. Then, the exercise intensity increased at 90% VO2max until exhaustion after supplementation. The average heart rate, maximal heart rate, running time to exhaustion and peak oxygen uptake were recorded during the exercise period. The body weight was recorded 15-min, 30-min, 45-min and 60-min of after EEE to calculate the dehydration rate and beverage hydration index (BHI). RESULTS: The dehydration rates in participants with ORS-SH@ treatment at 15-min, 30-min and 45-min of after EEE were significantly lower than with placebo treatment (-1.77±0.50% vs. -2.06±0.66%; -1.69±0.54% vs. -1.95±0.66%; -1.48±0.51% vs. -1.76±0.65%, respectively, p < .05). In addition, the BHI in participants with ORS-SH@ treatment at 15-min, 30-min and 45-min of after EEE (1.19±0.36, 1.22±0.43 and 1.27±0.54) were significantly higher than with placebo treatment (p < .05). However, there were no significant differences in other variables between treatments. CONCLUSIONS: ORS-SH@ supplementation can effectively enhance fluid retention after EEE. However, ORS-SH@ supplementation had no benefits on aerobic capacity. Supported by Panion & BF Biotech Inc. (Grant No: A-107-077)

Effects of different solutions consumed during exercise on cognitive function of male college soccer players

Background/Objectives: The present study aimed to investigate the effects of three solutions, i.e. carbohydrate-electrolyte-solution (CES), carbohydrate-electrolyte-protein-solution (CEPS), and placebo (PLA), on cognitive function of college soccer players. MethodsSixteen male college soccer players completed three main trials in a randomized cross-over study design. In each main trial, participants completed 90 min Loughborough Intermittent Shuttle Test (LIST) protocol and consumed one of three solutions. The cognitive function tests were performed; blood glucose and lactate concentrations, and several subjective measurements were also recorded in each trial. ResultsCompared with pre-exercise level, the accuracy of Rapid Visual Information Processing test (RVIPT) and the response time in Visual Search Test (VST, complex level) after LIST improved in CES and CEPS trials, but not in PLA trial. However, the accuracy of VST (complex level) decreased in both CES and CEPS trials, compared with PLA trial. CEPS consumption improved accuracy in VST (simple level), compared with CES consumption. Blood glucose concentrations were well maintained in CEPS trial, but not in CES and PLA trials. ConclusionIt seems that both CES and CEPS consumption show certain benefits on some aspects of cognitive function in male college soccer players in Hong Kong. However, these effects may be specific to the cognitive domain tested.

Hydration Efficacy of a Milk Permeate-Based Oral Hydration Solution.

Milk permeate is an electrolyte-rich, protein- and fat-free liquid with a similar carbohydrate and mineral content to that of milk. Its hydration efficacy has not been examined. The beverage hydration index (BHI) has been used to compare various beverages to water in terms of post-ingestion fluid balance and retention. Our purpose was to compare the BHI (and related physiological responses) of a novel milk permeate solution (MPS) to that of water and a traditional carbohydrate–electrolyte solution (CES). Over three visits, 12 young subjects consumed 1 L of water, CES, or MPS. Urine samples were collected immediately post-ingestion and at 60, 120, 180, and 240 min. BHI was calculated by dividing cumulative urine output after water consumption by cumulative urine output for each test beverage at each time point. The BHI for MPS was significantly higher at all time points compared to water (all p < 0.001) and CES (all p ≤ 0.01) but did not differ between CES and water at any time point. Drinking 1 L of MPS resulted in decreased cumulative urine output across the subsequent 4 h compared to water and CES, suggesting that a beverage containing milk permeate is superior to water and a traditional CES at sustaining positive fluid balance post-ingestion.

Low-Osmolality Carbohydrate-Electrolyte Solution Ingestion Avoid Fluid Loss and Oxidative Stress After Exhaustive Endurance Exercise.

Low-osmolality carbohydrate–electrolyte solution (LCS) ingestion can replace losses from exercise-induced dehydration, but the benefits of LCS ingestion strategy after exhaustive endurance exercise (EEE) remain unknown. The present study evaluated the effects of LCS ingestion on dehydration, oxidative stress, renal function, and aerobic capacity after EEE. In our study with its double-blind, crossover, counterbalanced design, 12 healthy male participants were asked to consume LCS (150 mL four times per hour) or placebo (water) 1 h before and 1 h after EEE. All participants completed a graded exercise test to exhaustion on a treadmill for the determination of maximal oxygen consumption (), applied to further intensity calibration, and then completed the EEE test. The average heart rate, maximal heart rate, running time to exhaustion, and peak oxygen uptake (VO2peak) were recorded during the exercise period. The participants’ body weight was recorded at different time points before and after the EEE to calculate the dehydration rate. Blood samples were drawn at baseline and before, immediately after, 1 h after, and 2 h after EEE to determine indicators of oxidative stress and renal function. The results indicated that the dehydration rates in participants with LCS ingestion at 15 min, 30 min, and 45 min after EEE were significantly lower than in participants with placebo ingestion (−1.86 ± 0.47% vs. −2.24 ± 0.72%; −1.78 ± 0.50% vs. −2.13 ± 0.74%; −1.54 ± 0.51% vs. −1.94 ± 0.72%, respectively; p < 0.05). In addition, the concentration of catalase in participants with LCS ingestion immediately after EEE was significantly higher than in participants with placebo ingestion (2046.21 ± 381.98 nmol/min/mL vs. 1820.37 ± 417.35 nmol/min/mL; p < 0.05). Moreover, the concentration of protein carbonyl in participants with LCS ingestion immediately after EEE was slightly lower than in participants with placebo ingestion (2.72 ± 0.31 nmol carbonyl/mg protein vs. 2.89 ± 0.43 nmol carbonyl/mg protein; p = 0.06). No differences were noted for other variables. Our findings conclude that LCS ingestion can effectively avoid fluid loss and oxidative stress after EEE. However, LCS ingestion had no benefits for renal function or aerobic capacity.

Impairment of Thermoregulation and Performance via Mild Dehydration in Ice Hockey Goaltenders.

This randomized, crossover study examined the effects of mild dehydration on goaltender on-ice thermoregulation, heart rate, fatigue, and performance. Eleven goaltenders played a 70-minute scrimmage followed by a shootout and drills to analyze reaction time and movements. On ice, they either consumed no fluid (NF) and lost 2.4% (0.3%) body mass or maintained body mass with water (WAT) or a carbohydrate-electrolyte solution (CES). Save percentage, rating of perceived exertion, heart rate, and core temperature were recorded throughout, and a postskate questionnaire assessed perceived fatigue. Relative to NF, intake of both fluids decreased heart rate (interaction: P = .03), core temperature (peak NF = 39.0°C [0.1°C], WAT = 38.6°C [0.1°C], and CES = 38.5°C [0.1°C]; P = .005), and rating of perceived exertion in the scrimmage (post hoc: P < .04), as well as increasing save percentage in the final 10 minutes of scrimmage (NF = 75.8% [1.9%], WAT = 81.7% [2.3%], and CES = 81.3% [2.3%], post hoc: P < .04). In drills, movement speed (post hoc: P < .05) and reaction time (post hoc: P < .04) were slower in the NF versus both fluid conditions. Intake of either fluid similarly reduced postskate questionnaire scores (condition: P < .0001). Only CES significantly reduced rating of perceived exertion in drills (post hoc: P < .05) and increased peak movement power versus NF (post hoc: P = .02). Shootout save percentage was similar between conditions (P = .37). Mild dehydration increased physiological strain and fatigue and decreased ice hockey goaltender performance versus maintaining hydration. Also, maintaining hydration with a CES versus WAT may further reduce perceived fatigue and positively affect movements.

Addition of sodium alginate and pectin to a carbohydrate-electrolyte solution does not influence substrate oxidation, gastrointestinal comfort, or cycling performance.

Eight well-trained cyclists ingested 68 g·h-1 of a carbohydrate-electrolyte solution with sodium alginate and pectin (CHO-ALG) or a taste and carbohydrate type-matched carbohydrate-electrolyte solution (CHO) during 120 min of cycling at 55% maximal power followed by an ∼20 min time trial. Oxygen uptake, carbon dioxide production, blood glucose concentration, substrate oxidation, gastrointestinal symptoms, and time trial performance (CHO-ALG: 1219 ± 84 s, CHO: 1267 ± 102 s; P = 0.185) were not different between trials. Novelty Inclusion of sodium alginate and pectin in a carbohydrate drink does not influence blood glucose, substrate oxidation, gastrointestinal comfort, or performance in cyclists.

Preoperative oral carb-electrolyte solution in elective laparoscopic total hysterectomy clinical effect observation

Objective To investigate the clinical effect of preoperative oral carb-electrolyte solution in selective laparoscopic total hysterectomy (TLH). Methods Using the judgment sampling method, 92 patients undergoing TLH surgery in the department of gynaecology of the hospital from May to November 2017 were selected as the study objects. They were randomly divided into the traditional fasting and no-drink group and the carbohydrate-electrolyte group, with 46 patients in each group.The Preoperative Self-perception Questionnaire designed by ourselves was used to investigate the self-perception of patients 1 hour before general anesthesia, and the 40-item postoperative recovery quality rating scale (QoR-40) was used to evaluate the postoperative recovery of patients. Binary Logistic regression analysis was used to explore the influencing factors of the total score of QoR-40. Results The rate of dry mouth, hunger, fatigue and anxiety in the carbohydrate-electrolyte group before operation were lower than those in the traditional fasting and no-drink group, and the differences were statistically significant(P<0.05). The results of t test showed that the total score of QoR-40, physical comfort, emotional state, self-care ability and psychological support of the subjects in the carbohydrate-electrolyte group were higher than those in the traditional fasting and no-drink group , and the differences were statistically significant(P<0.05). The recovery degree of the oral carbohydrate-electrolyte solution group was better than that of the traditional fasting and no-drink group 2 hours after surgery (OR=2.08). Conclusions Preoperative oral carb-electrolyte solution may improve the symptoms of hunger and dry mouth of TLH patients before surgery, and may promote the physical and mental recovery of TLH patients 2 hours after surgery. Key words: Carb-electrolyte solution; Laparoscopic total hysterectomy

Effect of a Carbohydrate-Electrolyte Solution on Fluid Balance and Performance at a Thermoneutral Environment in International-Level Fencers

Chryssanthopoulos, C, Tsolakis, C, Bottoms, L, Toubekis, A, Zacharogiannis, E, Pafili, Z, and Maridaki, M. Effect of a carbohydrate-electrolyte solution on fluid balance and performance at a thermoneutral environment in international-level fencers. J Strength Cond Res 34(1): 152-161, 2020-The purpose of the study was to examine a possible effect of a carbohydrate-electrolyte (CHO-E) solution on fluid balance and performance in fencing at a thermoneutral environment. Sixteen fencers performed two 120-minute training sessions separated by 7-14 days under similar environmental conditions (temperature: 20.3° C and humidity: 45-47%). Each session consisted of 60-minute conditioning exercises followed by 10 bouts of 3 minutes against the same opponent with 3-minute interval between each bout. Participants ingested at regular intervals either a 6% CHO-E solution or an artificially sweetened water (PL) in a counterbalanced order. No difference was observed between conditions in the heart rate responses, perceived exertion, changes in plasma volume, urine specific gravity, number of bouts won or lost, or points for and against. Considerable variability was observed in body mass changes that revealed significant differences at the time level (i.e., pre- vs. post-exercise) (F1,15 = 9.31, p = 0.008, η = 0.38), whereas no difference was found between conditions (i.e., CHO-E vs. PL) (F1,15 = 0.43, p = 0.52, η = 0.03) and conditions × time interaction (F1,15 = 3.57, p = 0.078, η = 0.19). Fluid loss was not significantly different between conditions (p = 0.08, d = 0.47). The blood glucose level was higher (p < 0.01) after exercise in CHO-E, whereas the blood lactate level was similar between conditions. In conclusion, the CHO-E solution was as effective as the artificially sweetened water in terms of fluid balance and fencing performance at a thermoneutral environment. Because of large individual variability, fencers should monitor their fluid intake and body fluid loss in training and competition.

Hydrogel Carbohydrate-Electrolyte Beverage Does Not Improve Glucose Availability, Substrate Oxidation, Gastrointestinal Symptoms or Exercise Performance, Compared With a Concentration and Nutrient-Matched Placebo.

The impact of a carbohydrate-electrolyte solution with sodium alginate and pectin for hydrogel formation (CES-HGel), was compared to a standard CES with otherwise matched ingredients (CES-Std), for blood glucose, substrate oxidation, gastrointestinal symptoms (GIS; nausea, belching, bloating, pain, regurgitation, flatulence, urge to defecate, and diarrhea), and exercise performance. Nine trained male endurance runners completed 3hr of steady-state running (SS) at 60% V˙O2max, consuming 90g/hr of carbohydrate from CES-HGel or CES-Std (53g/hr maltodextrin, 37g/hr fructose, 16% w/v solution) in a randomized crossover design, followed by an incremental time to exhaustion (TTE) test. Blood glucose and substrate oxidation were measured every 30min during SS and oxidation throughout TTE. Breath hydrogen (H2) was measured every 30min during exercise and every 15min for 2 hr postexercise. GIS were recorded every 15min throughout SS, immediately after and every 15-min post-TTE. No differences in blood glucose (incremental area under the curve [mean ± SD]: CES-HGel 1,100 ± 96mmol·L-1·150min-1 and CES-Std 1,076 ± 58mmol·L-1·150min-1; p = .266) were observed during SS. There were no differences in substrate oxidation during SS (carbohydrate: p = .650; fat: p = .765) or TTE (carbohydrate: p = .466; fat: p = .633) and no effect of trial on GIS incidence (100% in both trials) or severity (summative rating score: CES-HGel 29.1 ± 32.6 and CES-Std 34.8 ± 34.8; p = .262). Breath hydrogen was not different between trials (p = .347), nor was TTE performance (CES-HGel 722 ± 182s and CES-Std: 756 ± 187s; p = .08). In conclusion, sodium alginate and pectin added to a CES consumed during endurance running does not alter the blood glucose responses, carbohydrate malabsorption, substrate oxidation, GIS, or TTE beyond those of a CES with otherwise matched ingredients.

No Benefit of Ingestion of a Ketone Monoester Supplement on 10-km Running Performance.

Preexercise ingestion of exogenous ketones alters the metabolic response to exercise, but effects on exercise performance have been equivocal. On two occasions in a double-blind, randomized crossover design, eight endurance-trained runners performed 1 h of submaximal exercise at approximately 65% V˙O2max immediately followed by a 10-km self-paced time trial (TT) on a motorized treadmill. An 8% carbohydrate-electrolyte solution was consumed before and during exercise, either alone (CHO + PLA), or with 573 mg·kg of a ketone monoester supplement (CHO + KME). Expired air, HR, and RPE were monitored during submaximal exercise. Serial venous blood samples were assayed for plasma glucose, lactate, and β-hydroxybutyrate concentrations. CHO + KME produced plasma β-hydroxybutyrate concentrations of approximately 1.0 to 1.3 mM during exercise (P < 0.001), but plasma glucose and lactate concentrations were similar during exercise in both trials. V˙O2, running economy, respiratory exchange ratio, HR, and RPE were also similar between trials. Performance in the 10-km TT was not different (P = 0.483) between CHO + KME (mean, 2402 s; 95% confidence interval, 2204-2600 s) and CHO + PLA (mean, 2422 s; 95% confidence interval, 2217-2628 s). Cognitive performance, measured by reaction time and a multitasking test, did not differ between trials. Compared with carbohydrate alone, coingestion of KME by endurance-trained athletes elevated plasma β-hydroxybutyrate concentrations, but did not improve 10-km running TT or cognitive performance.

Intermittent Running and Cognitive Performance after Ketone Ester Ingestion

Ingestion of exogenous ketones alters the metabolic response to exercise and may improve exercise performance, but it has not been explored in variable-intensity team sport activity, or for effects on cognitive function. On two occasions in a double-blind, randomized crossover design, 11 male team sport athletes performed the Loughborough Intermittent Shuttle Test (part A, 5 × 15-min intermittent running; part B, shuttle run to exhaustion), with a cognitive test battery before and after. A 6.4% carbohydrate-electrolyte solution was consumed before and during exercise either alone (PLA) or with 750 mg·kg of a ketone ester (KE) supplement. Heart rate, RPE, and 15-m sprint times were recorded throughout, and serial venous blood samples were assayed for plasma glucose, lactate, and β-hydroxybutyrate. KE resulted in plasma β-hydroxybutyrate concentrations of ~1.5 to 2.6 mM during exercise (P < 0.001). Plasma glucose and lactate concentrations were lower during KE compared with PLA (moderate-to-large effect sizes). Heart rate, RPE, and 15-m sprint times did not differ between trials. Run time to exhaustion was not different (P = 0.126, d = 0.45) between PLA (mean = 268 s, 95% confidence interval [CI] = 199-336 s) and KE (mean = 229 s, 95% CI = 178-280 s). Incorrect responses in a multitasking test increased from pre- to postexercise in PLA (mean = 1.8, 95% CI = -0.6 to 4.1) but not in KE (mean = 0.0, 95% CI = -1.8 to 1.8) (P = 0.017, d = 0.70). Compared with carbohydrate alone, coingestion of a KE by team sport athletes attenuated the rise in plasma lactate concentrations but did not improve shuttle run time to exhaustion or 15-m sprint times during intermittent running. An attenuation of the decline in executive function after exhausting exercise suggests a cognitive benefit after KE ingestion.