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.

scholarly journals Complex I is bypassed during high intensity exercise

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Avlant Nilsson ◽  
Elias Björnson ◽  
Mikael Flockhart ◽  
Filip J. Larsen ◽  
Jens Nielsen
Keyword(s):  
High Intensity ◽  
Complex I ◽  
Atp Synthesis ◽  
Metabolic Model ◽  
High Intensity Exercise ◽  
Whole Body ◽  
Synthesis Rate ◽  
Proteomics Data ◽  
Exercise Tests

Abstract Human muscles are tailored towards ATP synthesis. When exercising at high work rates muscles convert glucose to lactate, which is less nutrient efficient than respiration. There is hence a trade-off between endurance and power. Metabolic models have been developed to study how limited catalytic capacity of enzymes affects ATP synthesis. Here we integrate an enzyme-constrained metabolic model with proteomics data from muscle fibers. We find that ATP synthesis is constrained by several enzymes. A metabolic bypass of mitochondrial complex I is found to increase the ATP synthesis rate per gram of protein compared to full respiration. To test if this metabolic mode occurs in vivo, we conduct a high resolved incremental exercise tests for five subjects. Their gas exchange at different work rates is accurately reproduced by a whole-body metabolic model incorporating complex I bypass. The study therefore shows how proteome allocation influences metabolism during high intensity exercise.

scholarly journals Creatine supplementation and age influence muscle metabolism during exercise

1998 ◽  
Vol 85 (4) ◽  
pp. 1349-1356 ◽  
Author(s):  
Sinclair A. Smith ◽  
Scott J. Montain ◽  
Ralph P. Matott ◽  
Gary P. Zientara ◽  
Ferenc A. Jolesz ◽  
...  
Keyword(s):  
Creatine Supplementation ◽  
Muscle Metabolism ◽  
Young Group ◽  
Knee Extension ◽  
Whole Body ◽  
Time To Exhaustion ◽  
Middle Aged ◽  
Aged Group ◽  
Placebo Trial ◽  
Knee Extension Exercise

Young [ n = 5, 30 ± 5 (SD) yr] and middle-aged ( n = 4, 58 ± 4 yr) men and women performed single-leg knee-extension exercise inside a whole body magnetic resonance system. Two trials were performed 7 days apart and consisted of two 2-min bouts and a third bout continued to exhaustion, all separated by 3 min of recovery.31P spectra were used to determine pH and relative concentrations of Pi, phosphocreatine (PCr), and β-ATP every 10 s. The subjects consumed 0.3 g ⋅ kg−1 ⋅ day−1of a placebo ( trial 1) or creatine ( trial 2) for 5 days before each trial. During the placebo trial, the middle-aged group had a lower resting PCr compared with the young group (35.0 ± 5.2 vs. 39.5 ± 5.1 mmol/kg, P < 0.05) and a lower mean initial PCr resynthesis rate (18.1 ± 3.5 vs. 23.2 ± 6.0 mmol ⋅ kg−1 ⋅ min−1, P < 0.05). After creatine supplementation, resting PCr increased 15% ( P < 0.05) in the young group and 30% ( P < 0.05) in the middle-aged group to 45.7 ± 7.5 vs. 45.7 ± 5.5 mmol/kg, respectively. Mean initial PCr resynthesis rate also increased in the middle-aged group ( P < 0.05) to a level not different from the young group (24.3 ± 3.8 vs. 24.2 ± 3.2 mmol ⋅ kg−1 ⋅ min−1). Time to exhaustion was increased in both groups combined after creatine supplementation (118 ± 34 vs. 154 ± 70 s, P < 0.05). In conclusion, creatine supplementation has a greater effect on PCr availability and resynthesis rate in middle-aged compared with younger persons.

Optimizing the “priming” effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance

2009 ◽  
Vol 107 (6) ◽  
pp. 1743-1756 ◽  
Author(s):  
Stephen J. Bailey ◽  
Anni Vanhatalo ◽  
Daryl P. Wilkerson ◽  
Fred J. DiMenna ◽  
Andrew M. Jones
Keyword(s):  
Exercise Intensity ◽  
High Intensity ◽  
Exercise Tolerance ◽  
Slow Component ◽  
High Intensity Exercise ◽  
Step Cycle ◽  
Exercise Tests ◽  
Recovery Duration ◽  
Prior Exercise ◽  
Ergometer Exercise

It has been suggested that a prior bout of high-intensity exercise has the potential to enhance performance during subsequent high-intensity exercise by accelerating the O2 uptake (V̇o2) on-response. However, the optimal combination of prior exercise intensity and subsequent recovery duration required to elicit this effect is presently unclear. Eight male participants, aged 18–24 yr, completed step cycle ergometer exercise tests to 80% of the difference between the preestablished gas exchange threshold and maximal V̇o2 (i.e., 80%Δ) after no prior exercise (control) and after six different combinations of prior exercise intensity and recovery duration: 40%Δ with 3 min (40-3-80), 9 min (40-9-80), and 20 min (40-20-80) of recovery and 70%Δ with 3 min (70-3-80), 9 min (70-9-80), and 20 min (70-20-80) of recovery. Overall V̇o2 kinetics were accelerated relative to control in all conditions except for 40-9-80 and 40-20-80 conditions as a consequence of a reduction in the V̇o2 slow component amplitude; the phase II time constant was not significantly altered with any prior exercise/recovery combination. Exercise tolerance at 80%Δ was improved by 15% and 30% above control in the 70-9-80 and 70-20-80 conditions, respectively, but was impaired by 16% in the 70-3-80 condition. Prior exercise at 40%Δ did not significantly influence exercise tolerance regardless of the recovery duration. These data demonstrate that prior high-intensity exercise (∼70%Δ) can enhance the tolerance to subsequent high-intensity exercise provided that it is coupled with adequate recovery duration (≥9 min). This combination presumably optimizes the balance between preserving the effects of prior exercise on V̇o2 kinetics and providing sufficient time for muscle homeostasis (e.g., muscle phosphocreatine and H+ concentrations) to be restored.

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.

scholarly journals Decrease of O2 deficit is a potential factor in increased time to exhaustion after specific endurance training

2001 ◽  
Vol 90 (3) ◽  
pp. 947-953 ◽  
Author(s):  
Alexandre P. Demarle ◽  
Jean J. Slawinski ◽  
Laurent P. Laffite ◽  
Valery G. Bocquet ◽  
Jean P. Koralsztein ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Training Program ◽  
Endurance Training ◽  
Slow Component ◽  
Maximal Oxygen Consumption ◽  
Interval Training ◽  
Oxygen Deficit ◽  
Time To Exhaustion ◽  
Before And After ◽  
Potential Factor

The main purpose of this study was to investigate the effects of an 8-wk severe interval training program on the parameters of oxygen uptake kinetics, such as the oxygen deficit and the slow component, and their potential consequences on the time until exhaustion in a severe run performed at the same absolute velocity before and after training. Six endurance-trained runners performed, on a 400-m synthetic track, an incremental test and an all-out test, at 93% of the velocity at maximal oxygen consumption, to assess the time until exhaustion. These tests were carried out before and after 8 wk of a severe interval training program, which was composed of two sessions of interval training at 93% of the velocity at maximal oxygen consumption and three recovery sessions of continuous training at 60–70% of the velocity at maximal oxygen consumption per week. Neither the oxygen deficit nor the slow component were correlated with the time until exhaustion ( r = −0.300, P = 0.24, n = 18 vs. r = −0.420, P = 0.09, n = 18, respectively). After training, the oxygen deficit significantly decreased ( P= 0.02), and the slow component did not change ( P = 0.44). Only three subjects greatly improved their time until exhaustion (by 10, 24, and 101%). The changes of oxygen deficit were significantly correlated with the changes of time until exhaustion ( r = −0.911, P = 0.01, n = 6). It was concluded that the decrease of oxygen deficit was a potential factor for the increase of time until exhaustion in a severe run performed after a specific endurance-training program.

Plasma Glutamine Responses to High-Intensity Exercise Before and After Endurance Training

2005 ◽  
Vol 13 (4) ◽  
pp. 287-300 ◽  
Author(s):  
Stephen Kargotich ◽  
Carmél Goodman ◽  
Brian Dawson ◽  
Alan R. Morton ◽  
David Keast ◽  
...  
Keyword(s):  
Endurance Training ◽  
High Intensity ◽  
High Intensity Exercise ◽  
Before And After

Effects of a prior high-intensity knee-extension exercise on muscle recruitment and energy cost: a combined local and global investigation in humans

2009 ◽  
Vol 94 (6) ◽  
pp. 704-719 ◽  
Author(s):  
Gwenael Layec ◽  
Aurélien Bringard ◽  
Yann Le Fur ◽  
Christophe Vilmen ◽  
Jean-Paul Micallef ◽  
...  
Keyword(s):  
Energy Cost ◽  
High Intensity ◽  
Knee Extension ◽  
Muscle Recruitment ◽  
Knee Extension Exercise
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