The present study aimed to investigate the influence of timing of preexercise carbohydrate feeding (Part A) and carbohydrate concentration (Part B) on short-duration high-intensity exercise capacity. In Part A, 17 males, and in Part B 10 males, performed a peak power output (PPO) test, two familiarization trials at 90% of PPO, and 4 (for Part A) or 3 (for Part B) experimental trials involving exercise capacity tests at 90% PPO. In Part A, the 4 trials were conducted following ingestion of a 6.4% carbohydrate/electrolyte sports drink ingested 30 (C30) or 120 (C120) minutes before exercise, or a flavor-matched placebo administered either 30 (P30) or 120 (P120) minutes before exercise. In Part B, the 3 trials were performed 30 min after ingestion of 0%, 2% or 12% carbohydrate solutions. All trials were performed in a double-blind cross-over design following and overnight fast. Dietary intake and activity in the 2 days before trials was recorded and replicated on each visit. Glucose, lactate, heart rate, and mood/arousal were recorded at intervals during the trials. In Part A, C30 produced the greatest exercise capacity (mean ± SD; 9.0 ± 1.9 min, p < .01) compared with all other trials (7.7 ± 1.5 min P30, 8.0 ± 1.7 min P120, 7.9 ± 1.9 min C120). In Part B, exercise capacity (min) following ingestion of the 2% solution (9.2 ± 2.1) compared with 0% (8.2 ± 0.7) and 12% (8.0 ± 1.3) solutions approached significance (p = .09). This study provides new evidence to suggest that timing of carbohydrate intake is important in short duration high-intensity exercise tasks, but a concentration effect requires further exploration.
Search Results
You are looking at 11 - 18 of 18 items for
- Author: Stuart D.R. Galloway x
- Refine by Access: All Content x
Preexercise Carbohydrate Feeding and High-Intensity Exercise Capacity: Effects of Timing of Intake and Carbohydrate Concentration
Stuart D.R. Galloway, Matthew J.E. Lott, and Lindsay C. Toulouse
Ingesting a 12% Carbohydrate-Electrolyte Beverage Before Each Half of a Soccer Match Simulation Facilitates Retention of Passing Performance and Improves High-Intensity Running Capacity in Academy Players
Paola Rodriguez-Giustiniani, Ian Rollo, Oliver C. Witard, and Stuart D. R. Galloway
This study investigated the influence of ingesting a 12% carbohydrate plus electrolyte (CHO-E) solution providing 60 g of carbohydrate before each half of a 90-min soccer match simulation (SMS) protocol on skill performance, sprint speed, and high-intensity running capacity. Eighteen elite academy (age: 18 ± 2 years) soccer players ingested two 250-ml doses (pre-exercise and at halftime) of a 12% CHO-E solution or electrolyte placebo administered in a double-blind randomized cross-over design. During an indoor (artificial grass pitch) SMS, dribbling, passing, and sprint performance were assessed, and blood was drawn for glucose and lactate analysis. High-intensity running capacity was assessed following the SMS. Dribbling speed/accuracy and sprint speed remained unchanged throughout the SMS. Conversely, passing accuracy for both dominant (mean percentage difference [95% confidence interval, CI]: 9 [3, 15]) and nondominant (mean percentage difference [95% CI]: 13 [6, 20]) feet was better maintained during the SMS on CHO-E (p < .05), with passing speed better maintained in the nondominant foot (mean percentage difference [95% CI]: 5.3 [0.7, 9.9], p = .032). High-intensity running capacity was greater in CHO-E versus placebo (mean percentage difference [95% CI]: 13 [6, 20], p = .010). Capillary blood glucose concentration was higher in CHO-E than placebo at halftime (CHO-E: 5.8 ± 0.5 mM vs. placebo: 4.1 ± 0.4 mM, p = .001) and following the high-intensity running capacity test (CHO-E: 4.9 ± 0.4 mM vs. placebo: 4.3 ± 0.4 mM, p = .001). Ingesting a 12% CHO-E solution before each half of a match can aid in the maintenance of soccer-specific skill performance, particularly on the nondominant foot, and improves subsequent high-intensity running capacity.
Effects of Dehydration on Cricket Specific Skill Performance in Hot and Humid Conditions
Janaka P. Gamage, Angela P. De Silva, Arjan K. Nalliah, and Stuart D.R. Galloway
The aim of the current study was to assess the effects of dehydration on cricket specific motor skill performance among fast-bowlers, fielders, and batsmen playing in a hot and humid environment. 10 fast-bowlers, 12 fielders and 8 batsmen participated in two field trials conducted 7 days apart: a fluid provision trial (FP) and a fluid restriction trial (FR). Each trial consisted of a 2-hr standardized training session and pretraining and posttraining skill performance assessments. Bowling speed and accuracy (line and length), throwing speed and accuracy (overarm, sidearm and underarm) and timed running between wickets (1, 2, and 3 runs) was assessed pre to posttraining in each trial. Mass loss was 0.6 ± 0.3 kg (0.9 ± 0.5%) in FP, and 2.6 ± 0.5kg (3.7 ± 0.8%) in FR trials. Maintaining mass within 1% of initial values did not cause any significant skill performance decline. However, the dehydration on the FR trial induced a significant time and trial effect for bowling speed by 1.0 ± 0.8% reduction (0.3 ± 0.8% reduction in FP trial; p < .01) and 19.8 ± 17.3% reduction in bowling accuracy for line (3.6 ± 14.2% reduction in FP trial; p < .01), but no effect on bowling length. A significant decline was noted in the FR trial for throwing speed for overarm (6.6 ± 4.1%; p < .01; 1.6 ± 3.4% reduction in FP trial) and sidearm (4.1 ± 2.3%; p < .01; 0.6 ± 4.7% increase in FP trial) techniques, and for throwing accuracy for overarm (14.2 ± 16.3%; p < .01; 0.8 ± 24.2% increase in FP trial) and sidearm (22.3 ± 13.3%; p < .05; 3.2 ± 34.9% reduction in FP trial) techniques. Batsmen demonstrated significant performance drop in making three runs (0.8 ± 1.2% increase in time in FP trial and 2.2 ± 1.7% increase in time in FR trial; p < .01). Moderate-severe dehydration of 3.7% body mass loss significantly impairs motor skill performance among cricketers, particularly bowlers and fielders, playing in hot and humid conditions. Fluid ingestion strategies maintaining mass loss within 1% prevented a decline in skill performance.
Associated Sociodemographic and Facility Patterning of Uptake, Attendance, and Session Count Within a Scottish Exercise Referral Scheme
Colin B. Shore, Gill Hubbard, Trish Gorely, Angus M. Hunter, and Stuart D.R. Galloway
Background: Exercise referral schemes (ERS) aim to tackle noncommunicable disease via increasing levels of physical activity. Health benefits are reliant on uptake and attending ERS sessions. Hence, it is important to understand which characteristics may influence these parameters to target interventions to improve uptake and attendance to those who need it most. Method: Secondary analysis of one ERS database was conducted to (1) profile participants’ nonuptake of exercise referral; (2) describe any differences between nonattenders and attenders; and (3) report session count of attenders, exploring any relationship between attender demographics and session count. Results: The study showed that (1) sociodemographic profile of nonattenders was very similar to that of those who attended; (2) there was a high, early withdrawal rate of attenders wherein 68% exited the scheme at 5 exercise sessions or less; and (3) session count did not appear to differ by demographic characteristics. Conclusions: Nonattendance and session count did not appear to differ by demographic characteristics. Attendance at ERS was low. Nonuptake and reduced attendance may limit any associated health benefits that may be achieved from ERS. Therefore, it is important to identify additional factors that may influence participants’ choice to uptake and attend ERS.
Adding Fish Oil to Whey Protein, Leucine, and Carbohydrate Over a Six-Week Supplementation Period Attenuates Muscle Soreness Following Eccentric Exercise in Competitive Soccer Players
Jordan D. Philpott, Chris Donnelly, Ian H. Walshe, Elizabeth E. MacKinley, James Dick, Stuart D.R. Galloway, Kevin D. Tipton, and Oliver C. Witard
Soccer players often experience eccentric exercise-induced muscle damage given the physical demands of soccer match-play. Since long chain n-3 polyunsaturated fatty acids (n-3PUFA) enhance muscle sensitivity to protein supplementation, dietary supplementation with a combination of fish oil–derived n-3PUFA, protein, and carbohydrate may promote exercise recovery. This study examined the influence of adding n-3PUFA to a whey protein, leucine, and carbohydrate containing beverage over a six-week supplementation period on physiological markers of recovery measured over three days following eccentric exercise. Competitive soccer players were assigned to one of three conditions (2 × 200 mL): a fish oil supplement beverage (FO; n = 10) that contained n-3PUFA (1100 mg DHA/EPA—approximately 550 mg DHA, 550 mg EPA), whey protein (15 g), leucine (1.8 g), and carbohydrate (20 g); a protein supplement beverage (PRO; n = 10) that contained whey protein (15 g), leucine (1.8 g), and carbohydrate (20 g); and a carbohydrate supplement beverage (CHO; n = 10) that contained carbohydrate (24 g). Eccentric exercise consisted of unilateral knee extension/flexion contractions on both legs separately. Maximal force production was impaired by 22% during the 72-hour recovery period following eccentric exercise (p < 0.05). Muscle soreness, expressed as area under the curve (AUC) during 72-hour recovery, was less in FO (1948 ± 1091 mm × 72 h) than PRO (4640 ± 2654 mm × 72 h, p < 0.05) and CHO (4495 ± 1853 mm × 72 h, p = 0.10). Blood concentrations of creatine kinase, expressed as AUC, were ~60% lower in FO compared to CHO (p < 0.05) and tended to be lower (~39%, p = 0.07) than PRO. No differences in muscle function, soccer performance, or blood c-reactive protein concentrations were observed between groups. In conclusion, the addition of n-3PUFA to a beverage containing whey protein, leucine, and carbohydrate ameliorates the increase in muscle soreness and blood concentrations of creatine kinase following eccentric exercise in competitive soccer players.
Effect of Drinking Rate on the Retention of Water or Milk Following Exercise-Induced Dehydration
Liam Sayer, Nidia Rodriguez-Sanchez, Paola Rodriguez-Giustiniani, Christopher Irwin, Danielle McCartney, Gregory R. Cox, Stuart D.R. Galloway, and Ben Desbrow
This study investigated the effect of drinking rate on fluid retention of milk and water following exercise-induced dehydration. In Part A, 12 male participants lost 1.9% ± 0.3% body mass through cycle exercise on four occasions. Following exercise, plain water or low-fat milk equal to the volume of sweat lost during exercise was provided. Beverages were ingested over 30 or 90 min, resulting in four beverage treatments: water 30 min, water 90 min, milk 30 min, and milk 90 min. In Part B, 12 participants (nine males and three females) lost 2.0% ± 0.3% body mass through cycle exercise on four occasions. Following exercise, plain water equal to the volume of sweat lost during exercise was provided. Water was ingested over 15 min (DR15), 45 min (DR45), or 90 min (DR90), with either DR15 or DR45 repeated. In both trials, nude body mass, urine volume, urine specific gravity and osmolality, plasma osmolality, and subjective ratings of gastrointestinal symptoms were obtained preexercise and every hour for 3 hr after the onset of drinking. In Part A, no effect of drinking rate was observed on the proportion of fluid retained, but milk retention was greater (p < .01) than water (water 30 min: 57% ± 16%, water 90 min: 60% ± 20%, milk 30 min: 83% ± 6%, and milk 90 min: 85% ± 7%). In Part B, fluid retention was greater in DR90 (57% ± 13%) than DR15 (50% ± 11%, p < .05), but this was within test–retest variation determined from the repeated trials (coefficient of variation: 17%). Within the range of drinking rates investigated the nutrient composition of a beverage has a more pronounced impact on fluid retention than the ingestion rate.
Sucrose and Sodium but not Caffeine Content Influence the Retention of Beverages in Humans Under Euhydrated Conditions
Ronald J. Maughan, Phillip Watson, Philip A.A. Cordery, Neil P. Walsh, Samuel J. Oliver, Alberto Dolci, Nidia Rodriguez-Sanchez, and Stuart D.R. Galloway
This study systematically examined the influence of carbohydrate (sucrose), sodium, and caffeine on the fluid retention potential of beverages under euhydrated conditions, using the beverage hydration index method. Three cohorts, each of 12 young, healthy, active men, ingested 1 L of beverages containing four different concentrations of a single component (sucrose, sodium, or caffeine) in a double-blind, crossover manner. Urine output was collected for the subsequent 4 hr. Cumulative urine output was lower and net fluid balance was higher after 10 and 20% sucrose beverages than 0 and 5% sucrose beverages (p < .05), and after 27 and 52 mmol/L sodium beverages than 7 and 15 mmol/L sodium beverages (p < .05). No difference in urine output or net fluid balance was apparent following ingestion of caffeine at concentrations of 0–400 mg/L (p = .83). Consequently, the calculated beverage hydration index was greater in beverages with higher sucrose or sodium content, but caffeine had no effect. No difference was observed in arginine vasopressin or aldosterone between any trials. These data highlight that the key drivers promoting differences in the fluid retention potential of beverages when euhydrated are energy density, likely through slowed fluid delivery to the circulation (carbohydrate content effect), or electrolyte content through improved fluid retention (sodium content effect). These data demonstrate that beverage carbohydrate and sodium content influence fluid delivery and retention in the 4 hr after ingestion, but caffeine up to 400 mg/L does not. Athletes and others can use this information to guide their daily hydration practices.
n-3 Fatty Acid Supplementation During 4 Weeks of Training Leads to Improved Anaerobic Endurance Capacity, but not Maximal Strength, Speed, or Power in Soccer Players
Leyre Gravina, Frankie F. Brown, Lee Alexander, James Dick, Gordon Bell, Oliver C. Witard, and Stuart D.R. Galloway
Omega-3 fatty acid (n-3 FA) supplementation could promote adaptation to soccer-specific training. We examined the impact of a 4-week period of n-3 FA supplementation during training on adaptations in 1RM knee extensor strength, 20-m sprint speed, vertical jump power, and anaerobic endurance capacity (Yo-Yo test) in competitive soccer players. Twenty six soccer players were randomly assigned to one of two groups: n-3 FA supplementation (n-3 FA; n = 13) or placebo (n = 13). Both groups performed two experimental trial days. Assessments of physical function and respiratory function were conducted pre (PRE) and post (POST) supplementation. Training session intensity, competitive games and nutritional intake were monitored during the 4-week period. No differences were observed in respiratory measurements (FEV1, FVC) between groups. No main effect of treatment was observed for 1RM knee extensor strength, explosive leg power, or 20 m sprint performance, but strength improved as a result of the training period in both groups (p < .05). Yo-Yo test distance improved with training in the n-3 FA group only (p < .01). The mean difference (95% CI) in Yo-Yo test distance completed from PRE to POST was 203 (66–340) m for n-3 FA, and 62 (-94–217) m for placebo, with a moderate effect size (Cohen’s d of 0.52). We conclude that 4 weeks of n-3 FA supplementation does not improve strength, power or speed assessments in competitive soccer players. However, the increase in anaerobic endurance capacity evident only in the n-3 FA treatment group suggests an interaction that requires further study.