Effects of caffeine, ephedrine and their combinations on time to exhaustion during high-intensity exercise

1999 ◽  
Vol 79 (4) ◽  
pp. 379-380 ◽  
Author(s):  
R. H. Morton
Keyword(s):  
High Intensity ◽  
High Intensity Exercise ◽  
Time To Exhaustion

Influence of endurance training on muscle [PCr] kinetics during high-intensity exercise

2007 ◽  
Vol 293 (1) ◽  
pp. R392-R401 ◽  
Author(s):  
Andrew M. Jones ◽  
Daryl P. Wilkerson ◽  
Nicolas J. Berger ◽  
Jonathan Fulford
Keyword(s):  
Endurance Training ◽  
High Intensity ◽  
Slow Component ◽  
Knee Extension ◽  
High Intensity Exercise ◽  
Whole Body ◽  
Time To Exhaustion ◽  
Exercise Tests ◽  
Before And After ◽  
Knee Extension Exercise

We hypothesized that a period of endurance training would result in a speeding of muscle phosphocreatine concentration ([PCr]) kinetics over the fundamental phase of the response and a reduction in the amplitude of the [PCr] slow component during high-intensity exercise. Six male subjects (age 26 ± 5 yr) completed 5 wk of single-legged knee-extension exercise training with the alternate leg serving as a control. Before and after the intervention period, the subjects completed incremental and high-intensity step exercise tests of 6-min duration with both legs separately inside the bore of a whole-body magnetic resonance spectrometer. The time-to-exhaustion during incremental exercise was not changed in the control leg [preintervention group (PRE): 19.4 ± 2.3 min vs. postintervention group (POST): 19.4 ± 1.9 min] but was significantly increased in the trained leg (PRE: 19.6 ± 1.6 min vs. POST: 22.0 ± 2.2 min; P < 0.05). During step exercise, there were no significant changes in the control leg, but end-exercise pH and [PCr] were higher after vs. before training. The time constant for the [PCr] kinetics over the fundamental exponential region of the response was not significantly altered in either the control leg (PRE: 40 ± 13 s vs. POST: 43 ± 10 s) or the trained leg (PRE: 38 ± 8 s vs. POST: 40 ± 12 s). However, the amplitude of the [PCr] slow component was significantly reduced in the trained leg (PRE: 15 ± 7 vs. POST: 7 ± 7% change in [PCr]; P < 0.05) with there being no change in the control leg (PRE: 13 ± 8 vs. POST: 12 ± 10% change in [PCr]). The attenuation of the [PCr] slow component might be mechanistically linked with enhanced exercise tolerance following endurance training.

The Effect of Pedal Rate and Time of Day on the Time to Exhaustion from High‐Intensity Exercise

2006 ◽  
Vol 23 (5) ◽  
pp. 1009-1024 ◽  
Author(s):  
N. Bessot ◽  
A. Nicolas ◽  
S. Moussay ◽  
A. Gauthier ◽  
B. Sesboüé ◽  
...  
Keyword(s):  
High Intensity ◽  
Time Of Day ◽  
High Intensity Exercise ◽  
Time To Exhaustion ◽  
Pedal Rate

Effects of Lactate Consumption on Blood Bicarbonate Levels and Performance During High-Intensity Exercise

2011 ◽  
Vol 21 (4) ◽  
pp. 311-317 ◽  
Author(s):  
David M. Morris ◽  
Rebecca S. Shafer ◽  
Kimberly R. Fairbrother ◽  
Mark W. Woodall
Keyword(s):  
Body Mass ◽  
High Intensity ◽  
Performance Test ◽  
Cycle Ergometer ◽  
High Intensity Exercise ◽  
Time To Exhaustion ◽  
Total Work ◽  
Male And Female ◽  
Lactate Consumption ◽  
And Performance

The authors sought to determine the effects of oral lactate consumption on blood bicarbonate (HCO3−) levels, pH levels, and performance during high-intensity exercise on a cycle ergometer. Subjects (N = 11) were trained male and female cyclists. Time to exhaustion (TTE) and total work were measured during high-intensity exercise bouts 80 min after the consumption of 120 mg/kg body mass of lactate (L), an equal volume of placebo (PL), or no treatment (NT). Blood HCO3− increased significantly after ingestion of lactate (p < .05) but was not affected in PL or NT (p > .05). No changes in pH were observed as a result of treatment. TTE and total work during the performance test increased significantly by 17% in L compared with PL and NT (p = .02). No significant differences in TTE and total work were seen between the PL and NT protocols (p = .85). The authors conclude that consuming 120 mg/kg body mass of lactate increases HCO3− levels and increases exercise performance during high-intensity cycling ergometry to exhaustion.

Predicting time to exhaustion during high-intensity exercise using rating of perceived exertion

2015 ◽  
Vol 30 (6) ◽  
pp. e155-e161
Author(s):  
N.M. Okuno ◽  
L.F. Soares-Caldeira ◽  
V.F. Milanez ◽  
L.A.B. Perandini
Keyword(s):  
High Intensity ◽  
Perceived Exertion ◽  
High Intensity Exercise ◽  
Rating Of Perceived Exertion ◽  
Time To Exhaustion

Strength Training Increases Endurance Time to Exhaustion During High-Intensity Exercise Despite No Change in Critical Power

2014 ◽  
Vol 28 (3) ◽  
pp. 601-609 ◽  
Author(s):  
Brandon J. Sawyer ◽  
David G. Stokes ◽  
Christopher J. Womack ◽  
R. Hugh Morton ◽  
Arthur Weltman ◽  
...  
Keyword(s):  
Strength Training ◽  
High Intensity ◽  
Critical Power ◽  
High Intensity Exercise ◽  
Time To Exhaustion ◽  
Endurance Time

Dietary nitrate supplementation reduces the O2cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans

2009 ◽  
Vol 107 (4) ◽  
pp. 1144-1155 ◽  
Author(s):  
Stephen J. Bailey ◽  
Paul Winyard ◽  
Anni Vanhatalo ◽  
Jamie R. Blackwell ◽  
Fred J. DiMenna ◽  
...  
Keyword(s):  
High Intensity ◽  
Submaximal Exercise ◽  
High Intensity Exercise ◽  
Moderate Intensity ◽  
Nitrate Content ◽  
Time To Exhaustion ◽  
Moderate Exercise ◽  
Dietary Nitrate ◽  
Nitrate Supplementation ◽  
Exercise In Humans

Pharmacological sodium nitrate supplementation has been reported to reduce the O2cost of submaximal exercise in humans. In this study, we hypothesized that dietary supplementation with inorganic nitrate in the form of beetroot juice (BR) would reduce the O2cost of submaximal exercise and enhance the tolerance to high-intensity exercise. In a double-blind, placebo (PL)-controlled, crossover study, eight men (aged 19–38 yr) consumed 500 ml/day of either BR (containing 11.2 ± 0.6 mM of nitrate) or blackcurrant cordial (as a PL, with negligible nitrate content) for 6 consecutive days and completed a series of “step” moderate-intensity and severe-intensity exercise tests on the last 3 days. On days 4–6, plasma nitrite concentration was significantly greater following dietary nitrate supplementation compared with PL (BR: 273 ± 44 vs. PL: 140 ± 50 nM; P < 0.05), and systolic blood pressure was significantly reduced (BR: 124 ± 2 vs. PL: 132 ± 5 mmHg; P < 0.01). During moderate exercise, nitrate supplementation reduced muscle fractional O2extraction (as estimated using near-infrared spectroscopy). The gain of the increase in pulmonary O2uptake following the onset of moderate exercise was reduced by 19% in the BR condition (BR: 8.6 ± 0.7 vs. PL: 10.8 ± 1.6 ml·min−1·W−1; P < 0.05). During severe exercise, the O2uptake slow component was reduced (BR: 0.57 ± 0.20 vs. PL: 0.74 ± 0.24 l/min; P < 0.05), and the time-to-exhaustion was extended (BR: 675 ± 203 vs. PL: 583 ± 145 s; P < 0.05). The reduced O2cost of exercise following increased dietary nitrate intake has important implications for our understanding of the factors that regulate mitochondrial respiration and muscle contractile energetics in humans.

scholarly journals Effect of Waters Enriched in O2 by Injection or Electrolysis on Performance and the Cardiopulmonary and Acid–Base Response to High Intensity Exercise

Nutrients ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 4320
Author(s):  
Frédéric N. Daussin ◽  
François Péronnet ◽  
Antoine Charton ◽  
Evelyne Lonsdorfer ◽  
Stéphane Doutreleau ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
High Intensity ◽  
Randomized Study ◽  
Lactate Concentration ◽  
Repeated Measurements ◽  
High Intensity Exercise ◽  
Time To Exhaustion ◽  
Psychological Benefits ◽  
Double Blind ◽  
Exercise Time

Several brands of water enriched with O2 (O2-waters) are commercially available and are advertised as wellness and fitness waters with claims of physiological and psychological benefits, including improvement in exercise performance. However, these claims are based, at best, on anecdotal evidence or on a limited number of unreliable studies. The purpose of this double-blind randomized study was to compare the effect of two O2-waters (~110 mg O2·L−1) and a placebo (10 mg O2·L−1, i.e., close to the value at sea level, 9–12 mg O2·L−1) on the cardiopulmonary responses and on performance during high-intensity exercise. One of the two O2-waters and the placebo were prepared by injection of O2. The other O2-water was enriched by an electrolytic process. Twenty male subjects were randomly allocated to drink one of the three waters in a crossover study (2 L·day−1 × 2 days and 15 mL·kg−1 90 min before exercise). During each exercise trial, the subjects exercised at 95.9 ± 4.7% of maximal workload to volitional fatigue. Exercise time to exhaustion and the cardiopulmonary responses, arterial lactate concentration and pH were measured. Oxidative damage to proteins, lipids and DNA in blood was assessed at rest before exercise. Time to exhaustion (one-way ANOVA) and the responses to exercise (two-way ANOVA [Time; Waters] with repeated measurements) were not significantly different among the three waters. There was only a trend (p = 0.060) for a reduction in the time constant of the rapid component of VO2 kinetics with the water enriched in O2 by electrolysis. No difference in oxidative damage in blood was observed between the three waters. These results suggest that O2-water does not speed up cardiopulmonary response to exercise, does not increase performance and does not trigger oxidative stress measured at rest.

Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans

2010 ◽  
Vol 109 (1) ◽  
pp. 135-148 ◽  
Author(s):  
Stephen J. Bailey ◽  
Jonathan Fulford ◽  
Anni Vanhatalo ◽  
Paul G. Winyard ◽  
Jamie R. Blackwell ◽  
...  
Keyword(s):  
High Intensity ◽  
Force Production ◽  
Knee Extensor ◽  
High Intensity Exercise ◽  
Nitrate Content ◽  
Time To Exhaustion ◽  
Exercise Tests ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Low Intensity

The purpose of this study was to elucidate the mechanistic bases for the reported reduction in the O2cost of exercise following short-term dietary nitrate (NO3−) supplementation. In a randomized, double-blind, crossover study, seven men (aged 19–38 yr) consumed 500 ml/day of either nitrate-rich beetroot juice (BR, 5.1 mmol of NO3−/day) or placebo (PL, with negligible nitrate content) for 6 consecutive days, and completed a series of low-intensity and high-intensity “step” exercise tests on the last 3 days for the determination of the muscle metabolic (using31P-MRS) and pulmonary oxygen uptake (V̇o2) responses to exercise. On days 4–6, BR resulted in a significant increase in plasma [nitrite] (mean ± SE, PL 231 ± 76 vs. BR 547 ± 55 nM; P < 0.05). During low-intensity exercise, BR attenuated the reduction in muscle phosphocreatine concentration ([PCr]; PL 8.1 ± 1.2 vs. BR 5.2 ± 0.8 mM; P < 0.05) and the increase in V̇o2(PL 484 ± 41 vs. BR 362 ± 30 ml/min; P < 0.05). During high-intensity exercise, BR reduced the amplitudes of the [PCr] (PL 3.9 ± 1.1 vs. BR 1.6 ± 0.7 mM; P < 0.05) and V̇o2(PL 209 ± 30 vs. BR 100 ± 26 ml/min; P < 0.05) slow components and improved time to exhaustion (PL 586 ± 80 vs. BR 734 ± 109 s; P < 0.01). The total ATP turnover rate was estimated to be less for both low-intensity (PL 296 ± 58 vs. BR 192 ± 38 μM/s; P < 0.05) and high-intensity (PL 607 ± 65 vs. BR 436 ± 43 μM/s; P < 0.05) exercise. Thus the reduced O2cost of exercise following dietary NO3−supplementation appears to be due to a reduced ATP cost of muscle force production. The reduced muscle metabolic perturbation with NO3−supplementation allowed high-intensity exercise to be tolerated for a greater period of time.

Sign in / Sign up

Export Citation Format

Share Document