Carbohydrate-electrolyte Solution Research Articles

Effects of Playing Position on Hydration Status in Collegiate Marching Band Musicians.

Marching band musicians often endure prolonged daily practices in warm-hot outdoor environments. Evaluation of hydration status by instrument position can shed light on health-related issues for these performers. The objective of this study was: a) to determine the effects of playing position on hydration status based on urinary biomarkers (urinary specific gravity and urinary osmolality) before and after marching band practice, and b) to evaluate the relation of hydration status with body mass change and fluid consumption for all playing positions. Fifty-eight collegiate marching band players participated in this study, involving five playing positions: band pit (n=10), baritone and euphonium (n=12), snare drum (n=13), trumpet (n=12), and tuba (n=11). All participants performed their own routine marching band practice, which lasted a total of 6 hrs on 1 day. Each individual consumed ad libitum commercially available carbohydrate-electrolyte solution during the practice. To determine hydration status, urine samples were collected before and after practice for analysis of urinary specific gravity and urinary osmolality. Body weight and total fluid intake were also assessed pre- and post-exercise. There were no significant effects for playing position and time or interaction concerning the levels of urinary osmolality and specific gravity after practice. Our main findings suggest that hydration status may be similar among the different playing positions following prolonged practice in the outdoor environment.

Fast Rehydration Rate Helps To Keep Positive Body Fluid Balance Longer Time

PURPOSE: To compare the effects of three different post exercise rehydration rates after exercise derived dehydration on body fluid balance and subjective feelings of thirstiness and bloating. METHODS: We evaluated five male college soccer players. They were weighted before performing a treadmill run to induce a ≈2% body weight loss by sweating. After the dehydration, subjects were rehydrated with 150% of their body weight loss with a carbohydrate electrolyte solution (5% CHO, 30 Na mEq/L). Subjects were assigned to one of three postexercise rehydration rates in a randomized, counterbalanced and crossover design. The postexercise rehydration rates consisted on drinking the whole fluid volume the first 30 minutes in 3 equal doses (H30), or the first 60 minutes in 5 equal doses (H60), or the first 120 minutes in 9 equal doses (H120) after dehydration. Subjects were weighted without clothes (after voiding their bladders and drying the skin with towels) each 30 minutes during a 240 minutes lapse. At the same time they answered a visual analogue scale to answer how thirsty and how bloated they felt at that moment. Results are presented as mean. A two-way repeated measures ANOVA was performed. RESULTS: Positive fluid balance in H30 was significantly higher than H60 and H120 at minute 30. H30 and H60 were higher than H120 at minute 60. H60 was higher than H120 at minute 90, but H30 was not different vs H60 nor H120. H30 kept a positive fluid balance for 2 hours, H60 for 1 hour, and H120 for 0.5 hours. Thirstiness was significantly lower in H30 than H120, but not to H60 at minute 30, no other difference was found. Bloating was significantly higher in H30 than H120, but not to H60 at minute 30, no other significant difference was found (Table 1). CONCLUSIONS: The H30 rehydration rate was effective to keep positive fluid balance for a longer period and to rapidly achieve positive fluid balance and decrease thirstiness acutely, however bloating may be a concern employing this rehydration rate.Table 1: Body fluid balance and subjective feelings of thirstiness and bloating by rehydration rateDifferent lowercase letters denotes significant differences (p<0.05) between rehydration rates at the same minute

Ingesting A Sports Drink Enhances Simulated Ice Hockey Performance While Reducing Perceived Effort.

This study determined whether ingesting a carbohydrate-electrolyte solution (CES) vs. progressive dehydration affected skeletal muscle glycogen use and performance in ice hockey players during simulated ice hockey exercise comprised of 3 active "periods". Seven males (21.3±0.3 years, 184.7±1.2 cm, 84.2±3.9 kg, and 49.6±1.8 mL·kg-1·min-1) performed a hockey-specific protocol on two occasions and either dehydrated progressively (NF), or stayed well-hydrated by ingesting a CES. Muscle biopsies were taken at rest, before the 3rd period (P3), and after the final sprint in the protocol. Compared to dehydration in the NF trial (-1.8% BM), CES ingestion enhanced voluntary performance (151.0±8.0 vs. 144.1±8.7 kJ) and glycogen use (177.5±31.1 vs. 103.5±16.2 mmol·kg dm-1), and reduced perceived exertion (16±1 vs. 18±1) in P3. Mean core temperature was reduced by CES ingestion throughout the protocol (38.0±0.2 vs. 38.1±0.1°C). These results suggest that compared to progressive dehydration, staying hydrated by ingesting a CES helps preserve performance, while reducing thermal and perceptual strains, in P3 of cycle-based simulation of ice hockey exercise. These benefits are observed despite greater glycogen use in P3 with CES ingestion.

Effect of protein and carbohydrate solutions on running performance and cognitive function in female recreational runners.

This study compared the effects of a carbohydrate–electrolyte–protein solution (CEPS, 2% protein plus 4% carbohydrate), carbohydrate–electrolyte solution (CES, 6% carbohydrate), and noncaloric sweetened placebo (PLA) on both 21-km running performance and cognitive function. Eleven female recreational endurance runners performed a 21-km time-trial running on three occasions, separated by at least 28 days. In a randomized cross-over design, they ingested CEPS, CES, or PLA at a rate of 150 mL every 2.5 km with no time feedback. A cognitive function test was performed before and after the run. Participants ingested approximately 24 g/h carbohydrate plus 12 g/h protein in CEPS trial, and 36 g/h carbohydrate in CES trial during each 21-km trial. Time to complete the time-trial was slightly shorter (P < 0.05) during CES (129.6 ± 8.8 min) than PLA (134.6 ± 11.5 min), with no differences between CEPS and the other two trials. The CEPS trial showed higher composite of visual motor speed than the PLA trial (P < 0.05). In conclusion, CES feedings might improve 21-km time-trial performance in female recreational runners compared with a PLA. However, adding protein to the CES provided no additional time-trial performance benefit. CEPS feeding during prolonged exercise could benefit visual motor speed compared to PLA alone, but no differences in the performance of the other cognitive function tests were found.

The Effect of Ad Libitum Carbohydrate-Electrolyte or Placebo Solution Intake on Fluid Balance and Soccer Skill Performance of Preadolescent Boys in Warm Environment

The Effect of Ad Libitum Carbohydrate-Electrolyte or Placebo Solution Intake on Fluid Balance and Soccer Skill Performance of Preadolescent Boys in Warm Environment

Effect of carbohydrate and protein solutions consumed during a moderate-intensity exercise on post-exercise appetite

This study aimed to investigate whether co-ingestion of carbohydrate and protein during exercise affect the post-exercise ad libitum food intake. Twelve healthy active male participants (mean±SD, age: 20±1; height: 176±6cm; weight: 63.6±5.3kg; VO2peak: 51.2±7.1ml/kg/min) completed three main experimental trials in a randomized cross-over design. In each trial, the participants completed 1h of ergometer cycling at 60% VO2peak, followed by 2h recovery. The participants were required to consume one of three solutions every 15min during exercise: distilled water (DW), carbohydrate-electrolyte solution (CE), and carbohydrate-electrolyte-protein solution (CEP). The energy was matched between the two latter solutions. The CHO-to-protein ratio in CEP was 2:1. At the end of recovery period, participants were provided with pizza lunch ad libitum, and the amount consumed was recorded. Several subjective feelings, appetite scores and blood glucose were determined during the experimental trials. No differences were found in either the amount of consumed pizza (DW vs. CE vs. CEP: 607±128 vs. 592±119 vs. 599±125g, P=0.845) or the appetite score before pizza was consumed (DW vs. CE vs. CEP: 14±9 vs. 12±14 vs. 14±10, P=0.357) among the three trials. The blood glucose concentrations during exercise were higher in the CE and CEP trials than in the DW trial. In conclusion, different solutions consumed during a 1h moderate-intensity exercise in the present study did not affect post-exercise appetite.

EFFECT OF CARBOHYDRATE-ELECTROLYTE-PROTEIN SOLUTION INGESTION ON 21 KM RUNNING PERFORMANCE IN FEMALE MARATHON RUNNERS

The purpose of the present study was to compare the effects of carbohydrate-electrolyte-protein solutions (CEPS), carbohydrate-electrolyte solutions (CES), and placebo (PLA) consumption on 21 km running performance in female runners....

NO EFFECT OF PRE-EXERCISE SUCRALOSE INGESTION ON GASTRIC EMPTYING RATE OF A CARBOHYDRATE-ELECTROLYTE SOLUTION

Ingestion of carbohydrate during exercise is common in order to provide an exogenous substrate for oxidation and to improve performance. The rate at which a solution is emptied from the...

A metered intake of milk following exercise and thermal dehydration restores whole-body net fluid balance better than a carbohydrate-electrolyte solution or water in healthy young men.

Appropriate rehydration and nutrient intake in recovery is a key component of exercise performance. This study investigated whether the recovery of body net fluid balance (NFB) following exercise and thermal dehydration to -2 % of body mass (BM) was enhanced by a metered rate of ingestion of milk (M) compared with a carbohydrate-electrolyte solution (CE) or water (W). In randomised order, seven active men (aged 26·2 (sd 6·1) years) undertook exercise and thermal dehydration to -2 % of BM on three occasions. A metered replacement volume of M, CE or W equivalent to 150 % of the BM loss was then consumed within 2-3 h. NFB was subsequently measured for 5 h from commencement of rehydration. A higher overall NFB in M than CE (P=0·001) and W (P=0·006) was observed, with no difference between CE and W (P=0·69). After 5 h, NFB in M remained positive (+117 (sd 122) ml) compared with basal, and it was greater than W (-539 (sd 390) ml, P=0·011) but not CE (-381 (sd 460) ml, P=0·077, d=1·6). Plasma osmolality (Posm) and K remained elevated above basal in M compared with CE and W. The change in Posm was associated with circulating pre-provasopressin (r s 0·348, P<0·001), a biomarker of arginine vasopressin, but could not account fully for the augmented NFB in M compared with CE and W. These data suggest that a metered approach to fluid ingestion acts in synergy with the nutrient composition of M in the restoration of NFB following exercise and thermal dehydration.

Low and moderate doses of caffeine late in exercise improve performance in trained cyclists.

The aim of the present study was to assess if low and moderate doses of caffeine delivered in a carbohydrate-electrolyte solution (CES) late in exercise improved time-trial (TT) performance. Fifteen (11 male, 4 female) cyclists (age, 22.5 ± 0.9 years; body mass, 69.3 ± 2.6 kg; peak oxygen consumption, 64.6 ± 1.9 mL·min(-1)·kg(-1)) completed 4 double-blinded randomized trials. Subjects completed 120 min of cycling at ∼60% peak oxygen consumption with 5 interspersed 120-s intervals at ∼82% peak oxygen consumption, immediately followed by 40-s intervals at 50 W. Following 80 min of cycling, subjects either ingested a 6% CES (PL), a CES with 100 mg (low dose, 1.5 ± 0.1 mg·kg body mass(-1)) of caffeine (CAF1), or a CES with 200 mg (moderate dose, 2.9 ± 0.1 mg·kg body mass(-1)) of caffeine (CAF2). Following the 120-min cycling challenge, cyclists completed a 6-kJ·kg body mass(-1) TT. There was no difference between respiratory, heart rate, glucose, free fatty acid, body mass, hematocrit, or urine specific gravity measurements between treatments. The CAF2 (26:36 ± 0:22 min:s) TT was completed faster than CAF1 (27:36 ± 0:32 min:s, p < 0.05) and both CAF1 and CAF2 TTs were completed faster than PL (28:41 ± 0:38 min:s, p < 0.05). Blood lactate was similar between trials and rose to a greater extent during the TT (p < 0.05). In summary, both doses of caffeine delivered late in exercise improved TT performance over the PL trial and the moderate dose (CAF2) improved performance to a greater extent than the low dose (CAF1).

Углеводно-электролитные растворы в спорте: обзор некоторых современных тенденций

Углеводно-электролитные растворы в спорте: обзор некоторых современных тенденций

Carbohydrate Nutrition and Team Sport Performance.

The common pattern of play in ‘team sports’ is ‘stop and go’, i.e. where players perform repeated bouts of brief high-intensity exercise punctuated by lower intensity activity. Sprints are generally 2–4 s long and recovery between sprints is of variable length. Energy production during brief sprints is derived from the degradation of intra-muscular phosphocreatine and glycogen (anaerobic metabolism). Prolonged periods of multiple sprints drain muscle glycogen stores, leading to a decrease in power output and a reduction in general work rate during training and competition. The impact of dietary carbohydrate interventions on team sport performance have been typically assessed using intermittent variable-speed shuttle running over a distance of 20 m. This method has evolved to include specific work to rest ratios and skills specific to team sports such as soccer, rugby and basketball. Increasing liver and muscle carbohydrate stores before sports helps delay the onset of fatigue during prolonged intermittent variable-speed running. Carbohydrate intake during exercise, typically ingested as carbohydrate-electrolyte solutions, is also associated with improved performance. The mechanisms responsible are likely to be the availability of carbohydrate as a substrate for central and peripheral functions. Variable-speed running in hot environments is limited by the degree of hyperthermia before muscle glycogen availability becomes a significant contributor to the onset of fatigue. Finally, ingesting carbohydrate immediately after training and competition will rapidly recover liver and muscle glycogen stores.

Carbohydrate Electrolyte Solutions Enhance Endurance Capacity in Active Females

The purpose of the present study was to investigate the effects of supplementation with a carbohydrate-electrolyte solution (CES) in active females during a prolonged session of submaximal running to exhaustion. Eight healthy active females volunteered to perform a session of open-ended running to exhaustion at 70% of their maximal oxygen consumption on a treadmill during the follicular phase of their menstrual cycle on two occasions. During each run, the subjects consumed either 3mL·kg−1 body mass of a 6% CES or a placebo drink (PL) every 20 min during exercise. The trials were administered in a randomized double-blind, cross-over design. During the run, the subjects ingested similar volumes of fluid in two trials (CES: 644 ± 75 mL vs. PL: 593 ± 66 mL, p > 0.05). The time to exhaustion was 16% longer during the CES trial (106.2 ± 9.4 min) than during the PL trial (91.6 ± 5.9 min) (p < 0.05). At 45 min during exercise, the plasma glucose concentration in the CES trial was higher than that in PL trial. No differences were observed in the plasma lactate level, respiratory exchange ratio, heart rate, perceived rate of exertion, sensation of thirst, or abdominal discomfort between the two trials (p > 0.05). The results of the present study confirm that CES supplementation improves the moderate intensity endurance capacity of active females during the follicular phases of the menstrual cycle. However, the exogenous oxidation of carbohydrate does not seem to explain the improved capacity after CES supplementation.

Fluid-regulating Hormones’ Responses After The Ingestion Of Carbohydrate-electrolyte-whey Protein Solution During Post-exercise Recovery

Dehydration is commonly observed after exercise, which may impair the exercise performance and cognitive functions. Compared with carbohydrate-electrolyte (CE) solution, the co-ingestion of CE solution and whey protein is found to improve the post-exercise rehydration; however, the potential mechanisms underlying the findings are not clear. PURPOSE: To investigate the responses of fluid-regulating hormones after the ingestion of CE solution with or without whey protein during post-exercise recovery. METHODS: Ten males (age: 22.0 ± 0.7 years; VO2max: 59.8 ± 1.9 ml/kg/min) completed 3 trials in a randomized crossover design. A 4-hour recovery was applied in each trial after 60 min run at 65% VO2max, during which the subjects ingested either a CE-H solution (66 g/L carbohydrate), a CE-L solution (33 g/L carbohydrate), or a CW solution (33 g/L carbohydrate, 33 g/L whey protein). All solutions were matched for their electrolytes content (Na+: 21 mmol/L; K+: 3.3 mmol/L). The total solution volume was equal to 150% of the body weight loss and was provided in 6 equal volumes every 30 min during recovery. Blood and urine samples were collected at 60 min intervals during recovery for analysis. RESULTS: The 60 min run induced ~2% of body weight loss in all trials. During recovery, a greater fluid retention was found in CW trial compared with CE-H and CE-L trials (CE-H vs. CE-L vs. CW: 38.4 ± 5.2% vs. 36.1 ± 4.3% vs. 55.4 ± 3.8%, p < 0.01). Aldosterone level under CE-L trial was lower than CW trial at the 3rd hour of recovery (CE-L vs. CW: 262 ± 60 pg/mL vs. 355 ± 73 pg/mL, p < 0.05). After recovery, aldosterone concentrations were lower in both CE-H and CE-L trials than CW trial (CE-H vs. CE-L vs. CW: 228 ± 100 pg/mL vs. 211 ± 51 pg/mL vs. 333 ± 70 pg/mL, p < 0.05). By the end of the 1st and 2nd hour of recovery, the antidiuretic hormone in CE-L trial was lower than that in CW trial, but no difference was found between CE-H and CW trial. CONCLUSIONS: The ingested CW solution was retained greater than the CE-H and CE-L solutions during a 4-hour recovery after the 60 min run, which was partly caused by the higher concentration of aldosterone in the CW trial. The higher concentration of antidiuretic hormone may also account for the greater fluid retention, but further studies are still needed to clarify this issue.

Response to comments on the Scientific Opinion of the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) on the scientific substantiation of a health claim related to carbohydrate solutions and maintenance of physical performance during endurance exercise pursuant to Article 13(5) of Regulation (EC) No 1924/2006

EFSA Supporting PublicationsVolume 12, Issue 4 797E Technical reportOpen Access Response to comments on the Scientific Opinion of the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) on the scientific substantiation of a health claim related to carbohydrate solutions and maintenance of physical performance during endurance exercise pursuant to Article 13(5) of Regulation (EC) No 1924/2006 European Food Safety Authority (EFSA), European Food Safety Authority (EFSA)Search for more papers by this author European Food Safety Authority (EFSA), European Food Safety Authority (EFSA)Search for more papers by this author First published: 20 April 2015 https://doi.org/10.2903/sp.efsa.2015.EN-797 Published date: 20 April 2015 Question number: EFSA-Q-2015-00009 AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on the substantiation of a health claim related to carbohydrate solutions and maintenance of physical performance during endurance exercise pursuant to Article 13(5) of Regulation (EC) No 1924/2006. EFSA Journal 2014; 12(10):3836, 6 pp. doi:10.2903/j.efsa.2014.3836 EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2011. Scientific Opinion on the substantiation of health claims related to carbohydrate-electrolyte solutions and reduction in rated perceived exertion/effort during exercise (ID 460, 466, 467, 468), enhancement of water absorption during exercise (ID 314, 315, 316, 317, 319, 322, 325, 332, 408, 465, 473, 1168, 1574, 1593, 1618, 4302, 4309), and maintenance of endurance performance (ID 466, 469) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal 2011; 9(6):2211, 29 pp. doi:10.2903/j.efsa.2011.2211 Karelis AD, Smith JW, Passe DH and Peronnet F, 2010. Carbohydrate administration and exercise performance: what are the potential mechanisms involved? Sports Medicine, 40, 747– 763. Temesi J, Johnson NA, Raymond J, Burdon CA and O'Connor HT, 2011. Carbohydrate ingestion during endurance exercise improves performance in adults. Journal of Nutrition, 141, 890– 897. Vandenbogaerde TJ and Hopkins WG, 2011. Effects of acute carbohydrate supplementation on endurance performance: a meta-analysis. Sports Medicine, 41, 773– 792. EFSA (European Food Safety Authority), Application of Systematic Review methodology to food and feed safety assessments to support decision making. The EFSA Journal 2010, 8(6):1637, pp 1– 90. Ntzani EE, Chondrogiorgi M, Ntritsos G, Evangelou E, Tzoulaki I, 2013. EFSA External Scientific Report. Literature review on epidemiological studies linking exposure to pesticides and health effects. Journal of the Science of Food and Agriculture, 18, 151– 153. EFSA supporting publication 2013:EN-497. Opinion of the French Agency for Food, Environmental and Occupational Health & Safety on the INSERM collective expert appraisal report “Pesticides. Health effects”, 2013. ANSES Opinion Request No. 2013-SA-0116. Pesticides Effets sur la santé. Éditions Inserm, Juillet, 2013, 1014 pages. Collection Expertise collective. ISBN 978-2-85598-905-1. Volume12, Issue4April 2015797E ReferencesRelatedInformation

Effects of protein addition to carbohydrate–electrolyte solutions on postexercise rehydration

Background/ObjectiveThis study aimed to examine the effects of the addition of whey or casein protein, the two major proteins in milk, to carbohydrate–electrolyte (CE) solutions on postexercise rehydration. MethodsTen young men aged 20.7 ± 1.4 years with an average VO2max of 60.7 mL/kg/min ran for 60 minutes at 65% VO2max on three occasions followed by 4 hours' recovery. During recovery, the participants consumed either CE solution with 66 g/L carbohydrate (CHO), or CE plus whey protein solution (CW trial, 44 g/L CHO, 22 g/L whey), or CE plus casein protein solution (CC trial, 44 g/L CHO, 22 g/L casein); the solutions were matched for energy and electrolyte content. ResultsThe participants lost 2.36 ± 0.32% of their pre-exercise body weight after the exercise. Total urine output after recovery was greater in the CE and CC trials than CW trial (CE vs. CW vs. CC: 1184 ± 378 mL vs. 1005 ± 214 mL vs. 1256 ± 413 mL; p < 0.05). Fluid retention after ingestion of CW solution was greater than CE and CC solutions (CE vs. CW vs. CC: 46.9 ± 16.5% vs. 54.9 ± 9.2% vs. 45.8 ± 17.3%; p < 0.05). Lower urine specific gravity and urine osmolality were observed by the end of recovery in the CE trial compared with CW trial (p < 0.05). No difference was found in the changes in plasma volume in all trials. ConclusionThese results suggest that during the 4 hours' recovery after a 60-minute run, the CW solution was more effective for rehydration compared with the CE or CC solution.

Effects of postexercise milk consumption on whole body protein balance in youth.

In adults, adding protein to a postexercise beverage increases muscle protein turnover and replenishes amino acid stores. Recent focus has shifted toward the use of bovine-based milk and milk products as potential postexercise beverages; however, little is known about how this research translates to the pediatric population. Twenty-eight (15 girls) pre- to early pubertal (PEP, 7-11 yr) and mid- to late-pubertal (MLP, 14-17 yr) children consumed an oral dose of [(15)N]glycine prior to performing 2 × 20-min cycling bouts at 60% V̇O(2 peak) in a warm environment (34.5°C, 47.3% relative humidity). Following exercise, participants consumed either water (W), a carbohydrate-electrolyte solution (CES), or skim milk (SM) in a randomized, cross-over fashion in a volume equal to 100% of their body mass loss during exercise. Whole body nitrogen turnover (Q), protein synthesis (S), protein breakdown (B), and whole body protein balance (WBPB) were measured over 16 h. Protein intake from SM was 0.40 ± 0.10 g/kg. Over 16 h, Q and S were significantly greater (P < 0.01) with SM than W and CES. B demonstrated a trend for a main effect for beverage (P = 0.063). WBPB was more negative (P < 0.01) with W and CES than with SM. In the SM trial, WBPB was positive in PEP, although it remained negative in MLP. Boys exhibited significantly more negative WBPB than girls (P < 0.05). Postexercise milk consumption enhances WBPB compared with W and CES; however, additional protein intake may be required to sustain a net anabolic environment over 16 h.

Effects of beverages with variable nutrients on rehydration and cognitive function.

The purpose of the present study was to investigate the effect of carbohydrate-electrolyte solution (CE), lemon tea (LT), and distilled water (DW) on rehydration and cognitive performance after 60 min of moderate exercise. 9 healthy males and 10 eumenorrheic females completed 3 runs in a randomized crossover study design. During the 4-h recovery (REC) period, they consumed either a volume of CE, LT or DW equal to 150% of their body mass (BM) loss during the previous run. The 3 beverages vary in carbohydrate and electrolyte content. A battery of cognitive tests was performed upon arrival, immediately after exercise, and at the end of REC. After the REC, the restoration of BM loss was lower in the DW and LT trials than that in the CE trial in the female participants (CE vs. LT vs. DW: 59.3±2.8 vs. 41.7±5.7 vs. 45.6±2.2%). When compared with the DW, the accuracy of performances during a working memory task in both males and females was higher in the CE and LT trials. The results suggested that during a short-term recovery, both LT and CE show certain beneficial effect in maintaining cognitive performance. However, CE appears to be more effective than LT and DW in rehydrating female participants.

Effects of a carbohydrate-electrolyte solution on cognitive performance following exercise-induced hyperthermia in humans.

BackgroundThere is limited information on the effects of sports drinks on cognitive function after exercise in the heat. We aimed to investigate the effects of ingesting a commercially available carbohydrate-electrolyte (CHO) solution on cognitive performance following exercise-induced hyperthermia.MethodsTwelve participants completed three practices of cognitive tests, one full familiarisation and two experimental trials in an environmental chamber (dry bulb temperature: 30.2 ± 0.3°C, relative humidity: 70 ± 3%). The experimental trials consisted of five cognitive tests (symbol digit matching, search and memory, digit span, choice reaction time and psychomotor vigilance test) performed before and after a 75-min run on a treadmill at 70% VO2 max. One ml/kg body mass of a 6.8% CHO solution or placebo was consumed at the start, every 15 min during exercise and between cognitive tests after exercise. Core temperature, heart rate, blood glucose concentrations, subjective ratings and cognitive performance were assessed (symbol digit matching, search and memory, digit span, choice reaction time and psychomotor vigilance).ResultsParticipants were hyperthermic at the end of the run (placebo: 39.5 ± 0.4°C, CHO: 39.6 ± 0.5°C; Mean ± SD; p = 0.37). The change in blood glucose was higher with CHO ingestion (1.6, 0.7 to 4.5 mmol/L) (median, range) than with placebo ingestion (0.9, -0.1 to 4.7 mmol/L; p < 0.05). CHO ingestion reduced the maximum span of digits memorized, in contrast to an increase in maximum span with placebo ingestion (p < 0.05). CHO solution had no effect on other cognitive tests (p > 0.05).ConclusionsThese results suggest that CHO solution ingestion may impair short-term memory following exertional heat stress.

Effect of milk consumption on rehydration in youth following exercise in the heat.

Low-fat milk is thought to be an effective postexercise rehydration beverage in adults; however, little is known about milk's rehydration ability in children after exercising in the heat. This study tested the hypothesis that because of its electrolyte and protein content, skim milk (SM) would be more effective than both water (W) and a carbohydrate/electrolyte solution (CES) in replacing body fluid losses in children following exercise in the heat. Thirty-eight (19 females) heat-acclimated pre- to early pubertal (PEP, aged 7-11 years) and mid- to late-pubertal (MLP, aged 14-17 years) children performed 3 sessions in 34.5 °C, 47.3% relative humidity, consisting of 2 × 20-min cycling bouts at 60% peak oxygen uptake followed by consumption of either W, CES, or SM. Each beverage was consumed immediately after exercise in a volume equal to 100% of their body mass loss during exercise. Urine samples were collected before, during, and after exercise, as well as the 2-h period following beverage consumption. On average, children dehydrated 1.3% ± 0.4%. Children ingested 0.40 ± 0.11 L (PEP) and 0.74 ± 0.20 L (MLP) of fluid. The fraction of the ingested beverage retained at 2 h of recovery was greater with SM (74% ± 18%) than W (47% ± 26%) and CES (59% ± 20%, p < 0.001 for both), and greater in CES than W (p < 0.001). All participants were in a hypohydrated state after 2 h of recovery, following the pattern SM < CES < W. In both PEP and MLP children, SM is more effective than W and CES at replacing fluid losses that occur during exercise in the heat.