scholarly journals Preexercise Carbohydrate Feeding and High-Intensity Exercise Capacity: Effects of Timing of Intake and Carbohydrate Concentration

2014 ◽  
Vol 24 (3) ◽  
pp. 258-266 ◽  
Author(s):  
Stuart D.R. Galloway ◽  
Matthew J.E. Lott ◽  
Lindsay C. Toulouse
Keyword(s):  
Exercise Capacity ◽  
Short Duration ◽  
High Intensity ◽  
High Intensity Exercise ◽  
Peak Power Output ◽  
Double Blind ◽  
Carbohydrate Concentration ◽  
Carbohydrate Feeding ◽  
Experimental Trials ◽  
New Evidence

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.

scholarly journals Evaluating the effects of caffeine and sodium bicarbonate, ingested individually or in combination, and a taste-matched placebo on high-intensity cycling capacity in healthy males

2016 ◽  
Vol 41 (4) ◽  
pp. 354-361 ◽  
Author(s):  
Matthew F. Higgins ◽  
Susie Wilson ◽  
Cameron Hill ◽  
Mike J. Price ◽  
Mike Duncan ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Sodium Bicarbonate ◽  
Body Mass ◽  
High Intensity ◽  
Peak Oxygen Uptake ◽  
Ion Concentration ◽  
Peak Power Output ◽  
Double Blind ◽  
Blood Ph ◽  
Experimental Trials

This study evaluated the effects of ingesting sodium bicarbonate (NaHCO3) or caffeine individually or in combination on high-intensity cycling capacity. In a counterbalanced, crossover design, 13 healthy, noncycling trained males (age: 21 ± 3 years, height: 178 ± 6 cm, body mass: 76 ± 12 kg, peak power output (Wpeak): 230 ± 34 W, peak oxygen uptake: 46 ± 8 mL·kg−1·min−1) performed a graded incremental exercise test, 2 familiarisation trials, and 4 experimental trials. Trials consisted of cycling to volitional exhaustion at 100% Wpeak (TLIM) 60 min after ingesting a solution containing either (i) 0.3 g·kg−1 body mass sodium bicarbonate (BIC), (ii) 5 mg·kg−1 body mass caffeine plus 0.1 g·kg−1 body mass sodium chloride (CAF), (iii) 0.3 g·kg−1 body mass sodium bicarbonate plus 5 mg·kg−1 body mass caffeine (BIC-CAF), or (iv) 0.1 g·kg−1 body mass sodium chloride (PLA). Experimental solutions were administered double-blind. Pre-exercise, at the end of exercise, and 5-min postexercise blood pH, base excess, and bicarbonate ion concentration ([HCO3−]) were significantly elevated for BIC and BIC-CAF compared with CAF and PLA. TLIM (median; interquartile range) was significantly greater for CAF (399; 350–415 s; P = 0.039; r = 0.6) and BIC-CAF (367; 333–402 s; P = 0.028; r = 0.6) compared with BIC (313: 284–448 s) although not compared with PLA (358; 290–433 s; P = 0.249, r = 0.3 and P = 0.099 and r = 0.5, respectively). There were no differences between PLA and BIC (P = 0.196; r = 0.4) or between CAF and BIC-CAF (P = 0.753; r = 0.1). Relatively large inter- and intra-individual variation was observed when comparing treatments and therefore an individual approach to supplementation appears warranted.

Failure of Glycine-Arginine-α-Ketoisocaproic Acid to Improve High-Intensity Exercise Performance in Trained Cyclists

2011 ◽  
Vol 21 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Lukas Beis ◽  
Yaser Mohammad ◽  
Chris Easton ◽  
Yannis P. Pitsiladis
Keyword(s):  
Exercise Performance ◽  
High Intensity ◽  
Perceived Exertion ◽  
Cycle Ergometer ◽  
High Intensity Exercise ◽  
Ratings Of Perceived Exertion ◽  
Mean Power ◽  
Double Blind ◽  
Oral Supplementation ◽  
Experimental Trials

Oral supplementation with glycine-arginine-α-ketoisocaproic acid (GAKIC) has previously been shown to improve exhaustive high-intensity exercise performance. There are no controlled studies involving GAKIC supplementation in well-trained subjects. The aim of the current study was to examine the effects of GAKIC supplementation on fatigue during high-intensity, repeated cycle sprints in trained cyclists. After at least 2 familiarization trials, 10 well-trained male cyclists completed 2 supramaximal sprint tests each involving 10 sprints of 10 s separated by 50-s rest intervals on an electrically braked cycle ergometer. Subjects ingested 11.2 g of GAKIC or placebo (Pl) during a period of 45 min before the 2 experimental trials, administered in a randomized and double-blind fashion. Peak power declined from the 1st sprint (M ± SD; Pl 1,332 ± 307 W, GAKIC 1,367 ± 342 W) to the 10th sprint (Pl 1,091 ± 229 W, GAKIC 1,061 ± 272 W) and did not differ between conditions (p = .88). Mean power declined from the 1st sprint (Pl 892 ± 151 W, GAKIC 892 ± 153 W) to the 10th sprint (Pl 766 ± 120 W, GAKIC 752 ± 138 W) and did not differ between conditions (p = .96). The fatigue index remained at ~38% throughout the series of sprints and did not differ between conditions (p = .99). Heart rate and ratings of perceived exertion increased from the 1st sprint to the 10th sprint and did not differ between conditions (p = .11 and p = .83, respectively). In contrast to previous studies in untrained individuals, these results suggest that GAKIC has no ergogenic effect on repeated bouts of high-intensity exercise in trained individuals.

Gastrointestinal Discomfort during Intermittent High-Intensity Exercise: Effect of Carbohydrate–Electrolyte Beverage

2004 ◽  
Vol 14 (6) ◽  
pp. 673-683 ◽  
Author(s):  
Xiaocai Shi ◽  
Mary K. Horn ◽  
Kris L. Osterberg ◽  
John R. Stofan, ◽  
Jeffrey J. Zachwieja ◽  
...  
Keyword(s):  
Randomized Trial ◽  
High Intensity ◽  
High Intensity Exercise ◽  
Double Blind ◽  
Stomach Upset ◽  
Cumulative Index ◽  
Carbohydrate Concentration ◽  
Gastrointestinal Discomfort ◽  
Exercise Effect ◽  
Vertical Jumps

This study investigated whether different beverage carbohydrate concentration and osmolality would provoke gastrointestinal (GI) discomfort during intermittent, high-intensity exercise. Thirty-six adult and adolescent athletes were tested on separate days in a double-blind, randomized trial of 6% and 8% carbohydrate-electrolytes (CHO-E) beverages during four 12-min quarters (Q) of circuit training that included intermittent sprints, lateral hops, shuttle runs, and vertical jumps. GI discomfort and fatigue surveys were completed before the first Q and immediately after each Q. All ratings of GI discomfort were modest throughout the study. The cumulative index for GI discomfort, however, was greater for the 8% CHO-E beverage than for the 6% CHO-E beverage at Q3 and Q4 (P < 0.05). Averaging across all 4 quarters, the 8% CHO-E treatment produced significantly higher mean ratings of stomach upset and side ache. In conclusion, higher CHO concentration and osmolality in an ingested beverage provokes stomach upset and side ache.

scholarly journals Expectancy of ergogenicity from sodium bicarbonate ingestion increases high-intensity cycling capacity

2016 ◽  
Vol 41 (4) ◽  
pp. 405-410 ◽  
Author(s):  
Matthew F. Higgins ◽  
Akbar Shabir
Keyword(s):  
Sodium Bicarbonate ◽  
High Intensity ◽  
Perceived Exertion ◽  
Metabolic Flux ◽  
Tap Water ◽  
Nutritional Supplement ◽  
Peak Power Output ◽  
Double Blind ◽  
Gut Fullness ◽  
Experimental Trials

This study examined whether expectancy of ergogenicity of a commonly used nutritional supplement (sodium bicarbonate; NaHCO3) influenced subsequent high-intensity cycling capacity. Eight recreationally active males (age, 21 ± 1 years; body mass, 75 ± 8 kg; height, 178 ± 4 cm; WPEAK = 205 ± 22 W) performed a graded incremental test to assess peak power output (WPEAK), one familiarisation trial and two experimental trials. Experimental trials consisted of cycling at 100% WPEAK to volitional exhaustion (TLIM) 60 min after ingesting either a placebo (PLA: 0.1 g·kg−1 sodium chloride (NaCl), 4 mL·kg−1 tap water, and 1 mL·kg−1 squash) or a sham placebo (SHAM: 0.1 g·kg−1 NaCl, 4 mL·kg−1 carbonated water, and 1 mL·kg−1 squash). SHAM aimed to replicate the previously reported symptoms of gut fullness (GF) and abdominal discomfort (AD) associated with NaHCO3 ingestion. Treatments were administered double blind and accompanied by written scripts designed to remain neutral (PLA) or induce expectancy of ergogenicity (SHAM). After SHAM mean TLIM increased by 9.5% compared to PLA (461 ± 148 s versus 421 ± 150 s; P = 0.048, d = 0.3). Ratings of GF and AD were mild but ∼1 unit higher post-ingestion for SHAM. After 3 min TLIM overall ratings of perceived exertion were 1.4 ± 1.3 units lower for SHAM compared to PLA (P = 0.020, d = 0.6). There were no differences between treatments for blood lactate, blood glucose, or heart rate. In summary, ergogenicity after NaHCO3 ingestion may be influenced by expectancy, which mediates perception of effort during subsequent exercise. The observed ergogenicity with SHAM did not affect our measures of cardiorespiratory physiology or metabolic flux.

scholarly journals Perception of Carbohydrate Availability Augments High-Intensity Intermittent Exercise Capacity Under Sleep-Low, Train-Low Conditions

2020 ◽  
Vol 30 (2) ◽  
pp. 105-111 ◽  
Author(s):  
Sally P. Waterworth ◽  
Connor C. Spencer ◽  
Aaron L. Porter ◽  
James P. Morton
Keyword(s):  
Steady State ◽  
Exercise Capacity ◽  
Body Mass ◽  
High Intensity ◽  
Intermittent Exercise ◽  
Peak Power Output ◽  
Future Research ◽  
Double Blind ◽  
Practical Applications ◽  
Practice Elements

The authors tested the hypothesis that perception of carbohydrate (CHO) availability augments exercise capacity in conditions of reduced CHO availability. Nine males completed a sleep-low train model comprising evening glycogen-depleting cycling followed by an exhaustive cycling protocol the next morning in the fasted state (30 min steady state at 95% lactate threshold followed by 1-min intervals at 80% peak power output until exhaustion). After the evening depletion protocol and prior to sleeping, subjects consumed (a) a known CHO intake of 6 g/kg body mass (TRAIN HIGH) or (b) a perceived comparable CHO intake but 0 g/kg body mass (PERCEPTION) or a known train-low condition of 0 g/kg body mass (TRAIN LOW). The TRAIN HIGH and PERCEPTION trials were conducted double blind. During steady state, average blood glucose and CHO oxidation were significantly higher in TRAIN HIGH (4.01 ± 0.56 mmol/L; 2.17 ± 0.70 g/min) versus both PERCEPTION (3.30 ± 0.57 mmol/L; 1.69 ± 0.64 g/min, p < .05) and TRAIN LOW (3.41 ± 0.74 mmol/L; 1.61 ± 0.59 g/min, p < .05). Exercise capacity was significantly different between all pairwise comparisons (p < .05), where TRAIN LOW (8 ± 8 min) < PERCEPTION (12 ± 6 min) < TRAIN HIGH (22 ± 9 min). Data demonstrate that perception of CHO availability augments high-intensity intermittent exercise capacity under sleep-low, train-low conditions, though this perception does not restore exercise capacity to that of CHO consumption. Such data have methodological implications for future research designs and may also have practical applications for athletes who deliberately practice elements of training in CHO-restricted states.

Six weeks of a polarized training-intensity distribution leads to greater physiological and performance adaptations than a threshold model in trained cyclists

2013 ◽  
Vol 114 (4) ◽  
pp. 461-471 ◽  
Author(s):  
Craig M. Neal ◽  
Angus M. Hunter ◽  
Lorraine Brennan ◽  
Aifric O'Sullivan ◽  
D. Lee Hamilton ◽  
...  
Keyword(s):  
Exercise Capacity ◽  
Intensity Distribution ◽  
High Intensity ◽  
Threshold Model ◽  
Endurance Performance ◽  
High Intensity Exercise ◽  
Metabolic Adaptation ◽  
Mitochondrial Enzyme ◽  
Training Intensity ◽  
Metabolomics Analysis

This study was undertaken to investigate physiological adaptation with two endurance-training periods differing in intensity distribution. In a randomized crossover fashion, separated by 4 wk of detraining, 12 male cyclists completed two 6-wk training periods: 1) a polarized model [6.4 (±1.4 SD) h/wk; 80%, 0%, and 20% of training time in low-, moderate-, and high-intensity zones, respectively]; and 2) a threshold model [7.5 (±2.0 SD) h/wk; 57%, 43%, and 0% training-intensity distribution]. Before and after each training period, following 2 days of diet and exercise control, fasted skeletal muscle biopsies were obtained for mitochondrial enzyme activity and monocarboxylate transporter (MCT) 1 and 4 expression, and morning first-void urine samples were collected for NMR spectroscopy-based metabolomics analysis. Endurance performance (40-km time trial), incremental exercise, peak power output (PPO), and high-intensity exercise capacity (95% maximal work rate to exhaustion) were also assessed. Endurance performance, PPOs, lactate threshold (LT), MCT4, and high-intensity exercise capacity all increased over both training periods. Improvements were greater following polarized rather than threshold for PPO [mean (±SE) change of 8 (±2)% vs. 3 (±1)%, P < 0.05], LT [9 (±3)% vs. 2 (±4)%, P < 0.05], and high-intensity exercise capacity [85 (±14)% vs. 37 (±14)%, P < 0.05]. No changes in mitochondrial enzyme activities or MCT1 were observed following training. A significant multilevel, partial least squares-discriminant analysis model was obtained for the threshold model but not the polarized model in the metabolomics analysis. A polarized training distribution results in greater systemic adaptation over 6 wk in already well-trained cyclists. Markers of muscle metabolic adaptation are largely unchanged, but metabolomics markers suggest different cellular metabolic stress that requires further investigation.

scholarly journals The Effects Of A Six-week Ketogenic Diet On The Performance Of Short-duration, High-intensity Exercise

2018 ◽  
Vol 50 (5S) ◽  
pp. 792 ◽  
Author(s):  
Emily M. Miele ◽  
Steven Vitti ◽  
Laura Christoph ◽  
Elizabeth C. O’Neill ◽  
Tracey D. Matthews ◽  
...  
Keyword(s):  
Ketogenic Diet ◽  
Short Duration ◽  
High Intensity ◽  
High Intensity Exercise

Time of day and short-duration high-intensity exercise influences on coagulation and fibrinolysis

2018 ◽  
Vol 18 (3) ◽  
pp. 367-375 ◽  
Author(s):  
Emma Kate Zadow ◽  
Cecilia Marie Kitic ◽  
Sam Shi Xuan Wu ◽  
James William Fell ◽  
Murray John Adams
Keyword(s):  
Short Duration ◽  
High Intensity ◽  
Time Of Day ◽  
High Intensity Exercise ◽  
Coagulation And Fibrinolysis

Pseudoephedrine is without ergogenic effects during prolonged exercise

1996 ◽  
Vol 81 (6) ◽  
pp. 2611-2617 ◽  
Author(s):  
Hunter Gillies ◽  
Wayne E. Derman ◽  
Timothy D. Noakes ◽  
Peter Smith ◽  
Alicia Evans ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
High Intensity ◽  
Muscle Function ◽  
Prolonged Exercise ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
High Intensity Exercise ◽  
Double Blind ◽  
Drug Concentrations ◽  
Ergogenic Effects

Gillies, Hunter, Wayne E. Derman, Timothy D. Noakes, Peter Smith, Alicia Evans, and Gary Gabriels.Pseudoephedrine is without ergogenic effects during prolonged exercise. J. Appl. Physiol. 81(6): 2611–2617, 1996.—This study was designed to measure whether a single dose of 120 mg pseudoephedrine ingested 120 min before exercise influences performance during 1 h of high-intensity exercise. The effects of exercise on urinary excretion of the drug were also studied. Ten healthy male cyclists were tested on two occasions, separated by at least 7 days, by using a randomly assigned, double-blind, placebo-controlled, crossover design. Exercise performance was tested during a 40-km trial on a laboratory cycle ergometer, and skeletal muscle function was measured during isometric contractions. On a third occasion, subjects ingested 120 mg pseudoephedrine but did not exercise [control (C)]. Pseudoephedrine did not influence either time trial performance [drug (D) vs. placebo: 58.1 ± 1.4 (SE) vs. 58.7 ± 1.5 min] or isometric muscle function. Urinary pseudoephedrine concentrations were significantly increased 1 h after exercise (D vs. C: 114.3 ± 27.2 vs. 35.4 ± 13.1 μg/ml; P < 0.05). Peak plasma pseudoephedrine concentrations ( P < 0.05) but not time taken to reach peak plasma concentrations or the area under the plasma pseudoephedrine concentration vs. time curve was significantly increased in the total group with exercise (D vs. C). In three subjects, plasma pseudoephedrine concentrations were not influenced by exercise. Only these subjects showed increased urinary pseudoephedrine excretion during exercise. We conclude that a single therapeutic dose of pseudoephedrine did not have a measurable ergogenic effect during high-intensity exercise of 1-h duration, but plasma drug concentrations and urinary excretion were altered by exercise. These findings have practical relevance to doping control regulations in international sporting competitions.

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