scholarly journals Ingesting a high-dose carbohydrate solution during the cycle section of a simulated Olympic-distance triathlon improves subsequent run performance

2012 ◽  
Vol 37 (4) ◽  
pp. 664-671 ◽  
Author(s):  
Kerry McGawley ◽  
Oliver Shannon ◽  
James Betts
Keyword(s):  
Blood Glucose ◽  
Oxygen Uptake ◽  
Body Mass ◽  
Time Trial ◽  
Peak Oxygen Uptake ◽  
High Dose ◽  
Stomach Upset ◽  
Single Discipline ◽  
Blood Glucose Concentrations ◽  
Carbohydrate Solution

The well-established ergogenic benefit of ingesting carbohydrates during single-discipline endurance sports has only been tested once within an Olympic-distance (OD) triathlon. The aim of the present study was to compare the effect of ingesting a 2:1 maltodextrin/fructose solution with a placebo on simulated OD triathlon performance. Six male and 4 female amateur triathletes (age, 25 ± 7 years; body mass, 66.8 ± 9.2 kg; peak oxygen uptake, 4.2 ± 0.6 L·min–1) completed a 1500-m swim time-trial and an incremental cycle test to determine peak oxygen uptake before performing 2 simulated OD triathlons. The swim and cycle sections of the main trials were of fixed intensities, while the run section was completed as a time-trial. Two minutes prior to completing every quarter of the cycle participants consumed 202 ± 20 mL of either a solution containing 1.2 g·min–1 of maltodextrin plus 0.6 g·min–1 of fructose at 14.4% concentration (CHO) or a sugar-free, fruit-flavored drink (PLA). The time-trial was 4.0% ± 1.3% faster during the CHO versus PLA trial, with run times of 38:43 ± 1:10 min:s and 40:22 ± 1:18 min:s, respectively (p = 0.010). Blood glucose concentrations were higher in the CHO versus PLA trial (p < 0.001), while perceived stomach upset did not differ between trials (p = 0.555). The current findings show that a 2:1 maltodextrin/fructose solution (1.8 g·min–1 at 14.4%) ingested throughout the cycle section of a simulated OD triathlon enhances subsequent 10-km run performance in triathletes.

Mouth rinsing with a carbohydrate solution does not influence cycle time trial performance in the heat

2014 ◽  
Vol 39 (9) ◽  
pp. 1064-1069 ◽  
Author(s):  
Phillip Watson ◽  
David Nichols ◽  
Philip Cordery
Keyword(s):  
Perceived Exertion ◽  
Time Trial ◽  
Peak Oxygen Uptake ◽  
Ratings Of Perceived Exertion ◽  
Experimental Trials ◽  
Blood Glucose Concentrations ◽  
Mouth Rinsing ◽  
Work Done ◽  
Carbohydrate Solution

Ten endurance-trained males were recruited to examine the possible role of carbohydrate (CHO) receptors in the mouth influencing exercise performance in the heat. Volunteers completed an incremental test to exhaustion to determine peak oxygen uptake, a familiarisation trial, followed by 2 experimental trials. Trials consisted of a 1-h time trial undertaken in a climatic chamber maintained at 30 °C, 60% relative humidity. Immediately before, and at regular intervals throughout exercise, subjects ingested a bolus of water and then were provided with either a placebo (PLA) or a 6.4% glucose (CHO) solution to rinse in the mouth for 10 s before being expectorated. There was no difference in total work done between the PLA and CHO trials (758.8 ± 149.0 kJ; 762.6 ± 141.1 kJ; P = 0.951). Pacing was also similar, with no differences in power output apparent during the experimental trials (P = 0.546). Core temperature (P = 0.615), heart rate (P = 0.505), ratings of perceived exertion (P = 0.181), and perceived thermal stress (P = 0.416) were not influenced by the nature of the intervention. Blood glucose concentrations were similar during the CHO and PLA trials (P = 0.117). In contrast to the findings of several studies undertaken in temperate conditions, the present investigation failed to support role of oral sensing of CHO in influencing performance during prolonged exercise in warm conditions.

scholarly journals Influence of sex-specific concurrent changes in age, maturity status, and morphological covariates on the development of peak ventilatory variables in 10–17-year-olds

2020 ◽  
Author(s):  
Neil Armstrong ◽  
Jo Welsman
Keyword(s):  
Oxygen Uptake ◽  
Tidal Volume ◽  
Body Mass ◽  
Explanatory Variable ◽  
Multilevel Modelling ◽  
Peak Oxygen Uptake ◽  
Anthropometric Measures ◽  
Allometric Models ◽  
Explanatory Variables ◽  
Temporal Spacing

Abstract Purposes (i) To investigate the influence of concurrent changes in age, maturity status, stature, body mass, and skinfold thicknesses on the development of peak ventilatory variables in 10–17-year-olds; and, (ii) to evaluate the interpretation of paediatric norm tables of peak ventilatory variables. Methods Multiplicative multilevel modelling which allows both the number of observations per individual and the temporal spacing of the observations to vary was used to analyze the expired ventilation (peak $${\dot{\mathrm{V}}}_{\mathrm{E}}$$ V ˙ E ) and tidal volume (peak VT) at peak oxygen uptake of 420 (217 boys) 10–17-year-olds. Models were founded on 1053 (550 from boys) determinations of peak ventilatory variables supported by anthropometric measures and maturity status. Results In sex-specific, multiplicative allometric models, concurrent changes in body mass and skinfold thicknesses (as a surrogate of FFM) and age were significant (p < 0.05) explanatory variables of the development of peak $${\dot{\mathrm{V}}}_{\mathrm{E}}$$ V ˙ E , once these covariates had been controlled for stature had no additional, significant (p > 0.05) effect on peak $${\dot{\mathrm{V}}}_{\mathrm{E}}$$ V ˙ E . Concurrent changes in age, stature, body mass, and skinfold thicknesses were significant (p < 0.05) explanatory variables of the development of peak VT. Maturity status had no additional, significant (p > 0.05) effect on either peak $${\dot{\mathrm{V}}}_{\mathrm{E}}$$ V ˙ E or peak VT once age and morphological covariates had been controlled for. Conclusions Elucidation of the sex-specific development of peak $${\dot{\mathrm{V}}}_{\mathrm{E}}$$ V ˙ E requires studies which address concurrent changes in body mass, skinfold thicknesses, and age. Stature is an additional explanatory variable in the development of peak VT, in both sexes. Paediatric norms based solely on age or stature or body mass are untenable.

Prediction of VO2peak from the 20-m Shuttle-Run Test in Youth With Down Syndrome

2011 ◽  
Vol 28 (2) ◽  
pp. 146-156 ◽  
Author(s):  
Stamatis Agiovlasitis ◽  
Kenneth H. Pitetti ◽  
Myriam Guerra ◽  
Bo Fernhall
Keyword(s):  
Body Mass Index ◽  
Down Syndrome ◽  
Oxygen Uptake ◽  
Regression Model ◽  
Body Mass ◽  
Prediction Equation ◽  
Peak Oxygen Uptake ◽  
Run Test ◽  
Shuttle Run

This study examined whether 20-m shuttle-run performance, sex, body mass index (BMI), age, height, and weight are associated with peak oxygen uptake (VO2peak) in youth with Down syndrome (DS; n = 53; 25 women, age 8–20 years) and whether these variables can be used to develop an equation to predict VO2peak. BMI, 20-m shuttle-run performance, and sex were significantly associated with VO2peak in youth with DS, whereas age, height, and weight were not. A regression model included only shuttle-run performance as a significant predictor of VO2peak; however, the developed prediction equation had low individual predictability. Therefore, 20-m shuttle-run performance alone does not provide valid prediction of VO2peak in youth with DS. Sex, BMI, age, height, and weight do not improve the prediction of VO2peak.

P2742Right ventricular stroke volume during dobutamine stress magnetic resonance compared to lung perfusion and peak oxygen uptake after arterial switch operation for transposition of the great arteries

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
M P Frick ◽  
S Ostermayer ◽  
S Hamada ◽  
A Kirschfink ◽  
N Marx ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Low Dose ◽  
Arterial Switch Operation ◽  
Dobutamine Stress ◽  
Peak Oxygen Uptake ◽  
High Dose ◽  
Pulmonary Perfusion ◽  
Cardiopulmonary Exercise ◽  
Peak Vo2 ◽  
High Dose Dobutamine

Abstract Objectives Abnormal pulmonary perfusion due to stenosis of the central pulmonary arteries is common after neonatal arterial switch operation (ASO) for transposition of the great arteries (TGA). We conducted a monocentric prospective study in young adults after neonatal ASO for TGA to evaluate the effects of abnormal pulmonary perfusion on the increase of the right ventricular stroke volume (RVSV) during dobutamine stress magnetic resonance (DSMR) and on cardiopulmonary exercise capacity. Methods 68 unselected patients (age 18–29 years) underwent CMR at rest and under dobutamine stress (10 to 40 μg/kg/min). RVSV, pulmonary blood flow distribution (PBFD) and peak flow velocity were derived from phase contrast mapping in the main, right and left pulmonary artery (PA) at rest and each stress level. A cardiopulmonary exercise test (CPET) was performed at the same day. All patients reached maximal exercise effort according to heart rate and respiratory exchange rate. Results PBFD at rest: 9/68 patients (13%, ASO-S) had abnormal pulmonary perfusion at rest, defined as PBFD >2:1 (right/left or left/right) and/or relevant stenosis of the main PA (Vmax >2.5 m/s). 59/68 patients (87%, ASO-N) had normal pulmonary perfusion. PBFD under DSMR: (1) In the whole patient group, there was no increase of PBFD under stress compared to PBFD at rest. On an individual patient level, no relevant worsening of abnormal PBFD was found. (2) Under low dose dobutamine, ASO-S had a significantly lower RVSV-increase (RVSVstress/RVSVrest) compared to ASO-N (see figure). However, under high dose dobutamine, this effect was no longer significant (see figure). (3) The RVSV-increase under low and high dose dobutamine did not correlate with peak oxygen uptake during CPET, neither in the total group nor in the subgroups (see table). Peak oxygen uptake was not significantly different between ASO-N and ASO-S (p=0,72). RVSV-increase compared to CPET peak VO2% ASO-total ASO-S ASO-N RVSV-increase/peak VO2% RVSV-increase/peak VO2% RVSV-increase/peak VO2% low dose dobu high dose dobu low dose dobu high dose dobu low dose dobu high dose dobu Pearson correlation coefficient −0.02 −0.05 0.01 −0.22 −0.05 −0.04 p-value 0.90 0.71 0.98 0.56 0.71 0.78 Figure 1 Conclusion (1) Patients with relevant stenosis of main PA and/or abnormal peripheral blood flow distribution (ASO-S) exhibit a reduced RVSV-increase under low dose dobutamine compared to patients without stenosis (ASO-N). This effect was not present under high dose dobutamine stress. (2) These findings did not correlate with peak oxygen uptake during CPET, an objective parameter of cardiopulmonary exercise capacity. (3) Therefore, a conservative proceeding rather than surgery or catheter intervention should be considered, especially in asymptomatic adult patients. Acknowledgement/Funding Supported by Kinderherzen, Fördergemeinschaft Deutsche Kinderherzzentren e.V.

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

2019 ◽  
Vol 127 (6) ◽  
pp. 1651-1659 ◽  
Author(s):  
Amadeo F. Salvador ◽  
Colleen F. McKenna ◽  
Rafael A. Alamilla ◽  
Ryan M. T. Cloud ◽  
Alexander R. Keeble ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Exercise Performance ◽  
Time Trial ◽  
Endurance Performance ◽  
Cycling Performance ◽  
Peak Oxygen Consumption ◽  
Gastric Emptying Rate ◽  
Subsequent Performance ◽  
Water Condition ◽  
Blood Glucose Concentrations

Carbohydrate (CHO) ingestion is an established strategy to improve endurance performance. Race fuels should not only sustain performance but also be readily digested and absorbed. Potatoes are a whole-food-based option that fulfills these criteria, yet their impact on performance remains unexamined. We investigated the effects of potato purée ingestion during prolonged cycling on subsequent performance vs. commercial CHO gel or a water-only condition. Twelve cyclists (70.7 ± 7.7 kg, 173 ± 8 cm, 31 ± 9 yr, 22 ± 5.1% body fat; means ± SD) with average peak oxygen consumption (V̇o2peak) of 60.7 ± 9.0 mL·kg−1·min−1 performed a 2-h cycling challenge (60–85% V̇o2peak) followed by a time trial (TT; 6 kJ/kg body mass) while consuming potato, gel, or water in a randomized-crossover design. The race fuels were administered with [U-13C6]glucose for an indirect estimate of gastric emptying rate. Blood samples were collected throughout the trials. Blood glucose concentrations were higher ( P < 0.001) in potato and gel conditions compared with water condition. Blood lactate concentrations were higher ( P = 0.001) after the TT completion in both CHO conditions compared with water condition. TT performance was improved ( P = 0.032) in both potato (33.0 ± 4.5 min) and gel (33.0 ± 4.2 min) conditions compared with water condition (39.5 ± 7.9 min). Moreover, no difference was observed in TT performance between CHO conditions ( P = 1.00). In conclusion, potato and gel ingestion equally sustained blood glucose concentrations and TT performance. Our results support the effective use of potatoes to support race performance for trained cyclists. NEW & NOTEWORTHY The ingestion of concentrated carbohydrate gels during prolonged exercise has been shown to promote carbohydrate availability and improve exercise performance. Our study aim was to expand and diversify race fueling menus for athletes by providing an evidence-based whole-food alternative to the routine ingestion of gels during training and competition. Our work shows that russet potato ingestion during prolonged cycling is as effective as carbohydrate gels to support exercise performance in trained athletes.

Hypoglycemia and torpor in Siberian hamsters

1999 ◽  
Vol 276 (3) ◽  
pp. R776-R781 ◽  
Author(s):  
John Dark ◽  
Daniel A. Lewis ◽  
Irving Zucker
Keyword(s):  
Blood Glucose ◽  
Body Temperature ◽  
Body Mass ◽  
Air Temperature ◽  
Day Length ◽  
Siberian Hamsters ◽  
Long Day ◽  
Necessary And Sufficient ◽  
Blood Glucose Concentrations ◽  
Torpor Bouts

We tested whether reduced blood glucose concentrations are necessary and sufficient for initiation of torpor in Siberian hamsters. During spontaneous torpor bouts, body temperature (Tb) decreases from the euthermic value of 37 to <31°C. Among hamsters that displayed torpor during maintenance in a short-day length (10 h light/day) at an air temperature of 15°C, blood glucose concentrations decreased significantly by 28% as Tb fell from 37 to <31°C and increased during rewarming so that by the time Tb first was >36°C, glucose concentrations had returned to the value preceding torpor. Hamsters did not display torpor when maintained in a long-day length (16 h light/day) and injected with a range of insulin doses (1–50 U/kg body mass), some of which resulted in sustained, pronounced hypoglycemia. We conclude that changes in blood glucose concentrations may be a consequence rather than a cause of the torpid state and question whether induction of torpor by 2-deoxy-d-glucose is due to its general glucoprivic actions.

Carbohydrate-Supplement Form and Exercise Performance

2008 ◽  
Vol 18 (2) ◽  
pp. 179-190 ◽  
Author(s):  
Caitlin Campbell ◽  
Diana Prince ◽  
Marlia Braun ◽  
Elizabeth Applegate ◽  
Gretchen A. Casazza
Keyword(s):  
Blood Glucose ◽  
Exercise Performance ◽  
Time Trial ◽  
Exercise Bout ◽  
Endurance Performance ◽  
Sports Drink ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Blood Glucose Concentrations ◽  
Carbohydrate Supplement

Numerous studies have shown that ingesting carbohydrate in the form of a drink can improve exercise performance by maintaining blood glucose levels and sparing endogenous glycogen stores. The effectiveness of carbohydrate gels or jellybeans in improving endurance performance has not been examined. On 4 separate days and 1–2 hr after a standardized meal, 16 male (8; 35.8 ± 2.5 yr) and female (8; 32.4 ± 2.4 yr) athletes cycled at 75% VO2peak for 80 min followed by a 10-km time trial. Participants consumed isocaloric (0.6 g of carbohydrate per kg per hour) amounts of randomly assigned sports beans, sports drink, gel, or water only, before, during, and after exercise. Blood glucose concentrations were similar at rest between treatments and decreased significantly during exercise with the water trial only. Blood glucose concentrations for all carbohydrate supplements were significantly, p < .05, higher than water during the 80-min exercise bout and during the time trial (5.7 ± 0.2 mmol/L for sports beans, 5.6 ± 0.2 mmol/L for sports drink, 5.7 ± 0.3 mmol/L for gel, and 4.6 ± 0.3 mmol/L for water). There were no significant differences in blood glucose between carbohydrate treatments. The 10-km time trials using all 3 carbohydrate treatments were significantly faster (17.2 ± 0.6 min for sports beans, 17.3 ± 0.6 min for sports drink, and 17.3 ± 0.6 min for gel) than water (17.8 ± 0.7 min). All carbohydrate-supplement types were equally effective in maintaining blood glucose levels during exercise and improving exercise performance compared with water only.

Effect of metformin on substrate utilization after exercise training in adults with impaired glucose tolerance

2013 ◽  
Vol 38 (4) ◽  
pp. 427-430 ◽  
Author(s):  
Steven K. Malin ◽  
Barry Braun
Keyword(s):  
Blood Glucose ◽  
Insulin Sensitivity ◽  
Exercise Training ◽  
Glucose Tolerance ◽  
Oxygen Uptake ◽  
Indirect Calorimetry ◽  
Substrate Utilization ◽  
Peak Oxygen Uptake ◽  
Whole Body ◽  
Glucose Kinetics

Metformin attenuates the higher insulin sensitivity that occurs with exercise training. Sixteen people with prediabetes trained for 10 weeks while taking metformin (n = 8) or placebo (n = 8). Substrate utilization was assessed using glucose kinetics and indirect calorimetry. After training, exercise whole-body fat oxidation was higher and glycogen use lower (p < 0.05), with no differences between groups. Blood glucose use was unchanged. Training-induced enhancement of insulin sensitivity (clamp) correlated with higher peak oxygen uptake (r = 0.70; p < 0.05), but was independent of glucose kinetic and substrate metabolism.

Sign in / Sign up

Export Citation Format

Share Document