scholarly journals The time course of adaptations in thermoneutral maximal oxygen consumption following heat acclimation

2019 ◽  
Vol 119 (10) ◽  
pp. 2391-2399 ◽  
Author(s):  
Mark Waldron ◽  
O. Jeffries ◽  
J. Tallent ◽  
S. Patterson ◽  
V. Nevola
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Time Course ◽  
Aerobic Power ◽  
Linear Time ◽  
Maximal Oxygen Consumption ◽  
Training Group ◽  
Heat Acclimation ◽  
Non Linear

Abstract Purpose This study investigated the effects of a 10-day heat acclimation (HA) programme on the time course of changes in thermoneutral maximal oxygen uptake ($$\dot{V}$$ V ˙ O2max) during and up to 10 days post-HA. Methods Twenty-two male cyclists were assigned to a HA or control (Con) training group following baseline ramp tests of thermoneutral $$\dot{V}$$ V ˙ O2max. Ten days of fixed-intensity (50% baseline $$\dot{V}$$ V ˙ O2max) indoor cycling was performed in either ~ 38.0 °C (HA) or ~ 20 °C (Con). $$\dot{V}$$ V ˙ O2max was re-tested on HA days 5, 10 and post-HA days 1, 2, 3, 4, 5 and 10. Results $$\dot{V}$$ V ˙ O2max initially declined across time in both groups during training (P < 0.05), before increasing in the post-HA period in both groups (P < 0.05). However, $$\dot{V}$$ V ˙ O2max was higher than control by post-HA day 4 in the HA group (P = 0.046). Conclusions The non-linear time course of $$\dot{V}$$ V ˙ O2max adaptation suggests that post-testing should be performed 96-h post-training to identify the maximal change for most individuals. In preparation for training or testing, athletes can augment their aerobic power in thermoneutral environments by performing 10 days HA, but the full effects will manifest at varying stages of the post-HA period.

Metabolic control of Argyropelecus hemigymnus photophores: effects of glucose and pyruvate

1991 ◽  
Vol 69 (9) ◽  
pp. 2410-2413 ◽  
Author(s):  
J. Mallefet ◽  
F. Baguet
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Metabolic Control ◽  
Time Course ◽  
Light Emission ◽  
Mesopelagic Fish ◽  
Fresh Weight ◽  
Hypometabolic State ◽  
The Mean ◽  
Mean Time

Modifications in oxygen consumption and luminescence of isolated luminescent organs of the mesopelagic fish Argyropelecus hemigymnus following glucose and pyruvate administration were studied before and during light emission triggered by adrenaline. Isolated photophores (mean fresh weight 13.5 ± 0.9 mg) at rest, i.e., in the absence of light emission, in saline (20 °C) exhibit a respiration rate of 1.045 ± 0.082 (SE) nmol O2/min (n = 35). A significant decrease (p = 0.05) in oxygen consumption was observed after the addition of 5.5 mM glucose. Instead of the oxygen decrease usually observed as a result of control stimulations using adrenaline, photophores pretreated with glucose increased their oxygen uptake in response to adrenaline, and maximal light emission was reduced by 85% (p = 0.01). The addition of 5.5 mM pyruvate induced a significant transient increase (p = 0.05) in oxygen uptake of isolated photophores, though this treatment did not statistically modify the mean time course of oxygen consumption and light emission in response to adrenaline. The hypothesis of a hypometabolic state of the isolated photophores of A. hemigymnus during light emission is discussed.

scholarly journals Performance Profile among Age Categories in Young Cyclists

Biology ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1196
Author(s):  
Cristian Marín-Pagán ◽  
Stéphane Dufour ◽  
Tomás T. Freitas ◽  
Pedro E. Alcaraz
Keyword(s):  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Ventilatory Threshold ◽  
Maximal Oxygen Consumption ◽  
Fat Oxidation ◽  
Threshold Power ◽  
Youth Group ◽  
Physiological Profile ◽  
Functional Parameters ◽  
Major Interest

Endurance profile assessment is of major interest to evaluate the cyclist’s performance potential. In this regard, maximal oxygen uptake and functional threshold power are useful functional parameters to determine metabolic training zones (ventilatory threshold). The aim of this study was to evaluate and compare the physiological profile of different road cyclist age categories (Youth, Junior, and Under-23) to obtain the performance requirements. Sixty-one competitive road cyclists (15–22 years) performed a maximal incremental test on a bike in order to determine functional parameters (maximal fat oxidation zone, ventilatory thresholds, maximal oxygen uptake, and functional threshold power) and metabolic training zones. The results suggest major differences, with the Youth group showing clear changes in all metabolic zones except in fat oxidation. The main differences between Under-23 vs. Junior groups were observed in maximal relative power output (Under-23: 6.70 W·Kg−1; Junior: 6.17 W·Kg−1) and relative functional threshold power (Under-23: 4.91 W·Kg−1; Junior: 4.48 W·Kg−1). The Youth group physiological profile is clearly different to the other age categories. Some parameters normalized to body weight (maximal oxygen consumption, load and functional threshold power) could be interesting to predict a sporting career during the Junior and Under-23 stages.

Effects of high-intensity exercise training on body composition, abdominal fat loss, and cardiorespiratory fitness in middle-aged Korean females

2012 ◽  
Vol 37 (6) ◽  
pp. 1019-1027 ◽  
Author(s):  
Man-Gyoon Lee ◽  
Kyung-Shin Park ◽  
Do-Ung Kim ◽  
Soon-Mi Choi ◽  
Hyoung-Jun Kim
Keyword(s):  
Oxygen Consumption ◽  
Exercise Training ◽  
High Intensity ◽  
Maximal Oxygen Consumption ◽  
Training Group ◽  
Abdominal Fat ◽  
High Intensity Exercise ◽  
Whole Body ◽  
Fat Loss ◽  
Intensity Training

The primary purpose of this study was to investigate the effects of high-intensity exercise training under relatively equal energy expenditure on whole body fat and abdominal fat loss, and cardiorespiratory fitness. Twenty-two untrained middle-aged Korean females were randomized into one of the following groups: control, low-intensity training group (LI), and high-intensity training group (HI). Subjects completed 14 weeks of training at 50% maximal oxygen consumption (LI) or 70% maximal oxygen consumption (HI) with the volume of exercise equated relative to kilograms of body weight. Weekly exercise volumes were 13.5 METs⋅h/week for the first 4 weeks, 18 METs⋅h/week for next 5 weeks, and 22.5 METs⋅h/week for the final 5 weeks. Data were analyzed using 2-way repeated measures ANOVA with post hoc test, using Bonferroni’s correction. HI showed significant reductions in fat mass (p < 0.05), total abdominal fat (p < 0.01), and subcutaneous abdominal fat (p < 0.01). LI reduced total abdominal fat (p < 0.05), but there were no other significant changes found in the control or LI groups. Maximal oxygen consumption was enhanced in both HI and LI with no significant group difference. High-density lipoprotein cholesterol increased significantly in HI (p < 0.05). IL-6, C-reactive protein, TNF-α, and other blood lipids were unaltered following training. Results indicate that high-intensity exercise training is more beneficial in whole body and abdominal fat loss; however, cardiorespiratory enhancement shows a dose–response relationship with weekly exercise volume. It is suggested that 14 weeks of aerobic exercise training at either high- or low-intensity is not sufficient enough to induce changes in levels of inflammatory proteins.

scholarly journals Heat Acclimation by Postexercise Hot-Water Immersion: Reduction of Thermal Strain During Morning and Afternoon Exercise-Heat Stress After Morning Hot-Water Immersion

2018 ◽  
Vol 13 (10) ◽  
pp. 1281-1286 ◽  
Author(s):  
Michael J. Zurawlew ◽  
Jessica A. Mee ◽  
Neil P. Walsh
Keyword(s):  
Heat Stress ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Perceived Exertion ◽  
Water Immersion ◽  
Heat Acclimation ◽  
Time Of Day ◽  
Hot Water ◽  
Rating Of Perceived Exertion ◽  
Hot Water Immersion

Purpose: Recommendations state that to acquire the greatest benefit from heat-acclimation, the clock time of heat-acclimation sessions should match that of expected exercise-heat stress. It remains unknown if adaptations by postexercise hot-water immersion (HWI) demonstrate time-of-day-dependent adaptations. Thus, the authors examined whether adaptations following postexercise HWI completed in the morning were present during morning and afternoon exercise-heat stress. Methods: Ten males completed an exercise-heat stress test commencing in the morning (9:45 AM) and afternoon (2:45 PM; 40 min; 65% of maximal oxygen uptake treadmill run) before and after heat-acclimation. The 6-d heat-acclimation intervention involved a daily 40-min treadmill run (65% of maximal oxygen uptake) in temperate conditions followed by ≤40-min HWI (40°C; 6:30–11:00 AM). Results: Adaptations by 6-d postexercise HWI in the morning were similar in the morning and afternoon. Reductions in resting rectal temperature (Tre) (AM −0.34°C [0.24°C], PM −0.27°C [0.23°C]; P = .002), Tre at sweating onset (AM −0.34°C [0.24°C], PM −0.31°C [0.25°C]; P = .001), and end-exercise Tre (AM −0.47°C [0.33°C], PM −0.43°C [0.29°C]; P = .001), heart rate (AM −14 [7] beats·min−1, PM −13 [6] beats·min−1; P < .01), rating of perceived exertion (P = .01), and thermal sensation (P = .005) were not different in the morning compared with the afternoon. Conclusion: Morning heat acclimation by postexercise HWI induced adaptations at rest and during exercise-heat stress in the morning and midafternoon.

Effect of small vs large muscle mass endurance training on maximal oxygen uptake in organ transplanted recipients

2021 ◽  
pp. 1-10
Author(s):  
Alessio del Torto ◽  
Carlo Capelli ◽  
Roberto Peressutti ◽  
Adriana di Silvestre ◽  
Ugolino Livi ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Endurance Training ◽  
Maximal Oxygen Consumption ◽  
Factors Affecting ◽  
Maximal Cardiac Output ◽  
Leg Cycling ◽  
Before And After ◽  
Large Muscle

Maximal oxygen consumption (V̇O2max) is impaired in heart (HTx), kidney (KTx), and liver (LTx) transplanted recipients and the contribution of the cardiovascular, central, and peripheral (muscular) factors in affecting V̇O2max improvement after endurance training (ET) has never been quantified in these patients. ET protocols involving single leg cycling (SL) elicit larger improvements of the peripheral factors affecting O2 diffusion and utilization than the double leg (DL) cycling ET. Therefore, this study aimed to compare the effects of SL-ET vs DL-ET on V̇O2max. We determined the DL-V̇O2max and maximal cardiac output before and after 24 SL-ET vs DL-ET sessions on 33 patients (HTx = 13, KTx = 11 and LTx = 9). The DL-V̇O2max increased by 13.8% ± 8.7 (p < 0.001) following the SL-ET, due to a larger maximal O2 systemic extraction; meanwhile, V̇O2max in DL-ET increased by 18.6% ± 12.7 (p < 0.001) because of concomitant central and peripheral adaptations. We speculate that in transplanted recipients, SL-ET is as effective as DL-ET to improve V̇O2max and that the impaired peripheral O2 extraction and/or utilization play an important role in limiting V̇O2max in these types of patients. Novelty: SL-ET increases V̇O2max in transplanted recipients because of improved peripheral O2 extraction and/or utilization. SL-ET is as successful as DL-ET to improve the cardiorespiratory fitness in transplanted recipients. The model of V̇O2max limitation indicates the peripheral factors as a remarkable limitation to the V̇O2max in these patients.

scholarly journals Does recombinant human Epo increase exercise capacity by means other than augmenting oxygen transport?

2008 ◽  
Vol 105 (2) ◽  
pp. 581-587 ◽  
Author(s):  
C. Lundby ◽  
P. Robach ◽  
R. Boushel ◽  
J. J. Thomsen ◽  
P. Rasmussen ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Oxygen Delivery ◽  
Maximal Oxygen Consumption ◽  
Hemoglobin Concentration ◽  
Arterial Oxygen ◽  
Peak Exercise ◽  
Healthy Humans ◽  
Human Erythropoietin ◽  
Oxygen Carrying Capacity

This study was performed to test the hypothesis that administration of recombinant human erythropoietin (rHuEpo) in humans increases maximal oxygen consumption by augmenting the maximal oxygen carrying capacity of blood. Systemic and leg oxygen delivery and oxygen uptake were studied during exercise in eight subjects before and after 13 wk of rHuEpo treatment and after isovolemic hemodilution to the same hemoglobin concentration observed before the start of rHuEpo administration. At peak exercise, leg oxygen delivery was increased from 1,777.0 ± 102.0 ml/min before rHuEpo treatment to 2,079.8 ± 120.7 ml/min after treatment. After hemodilution, oxygen delivery was decreased to the pretreatment value (1,710.3 ± 138.1 ml/min). Fractional leg arterial oxygen extraction was unaffected at maximal exercise; hence, maximal leg oxygen uptake increased from 1,511.0 ± 130.1 ml/min before treatment to 1,793.0 ± 148.7 ml/min with rHuEpo and decreased after hemodilution to 1,428.0 ± 111.6 ml/min. Pulmonary oxygen uptake at peak exercise increased from 3,950.0 ± 160.7 before administration to 4,254.5 ± 178.4 ml/min with rHuEpo and decreased to 4,059.0 ± 161.1 ml/min with hemodilution ( P = 0.22, compared with values before rHuEpo treatment). Blood buffer capacity remained unaffected by rHuEpo treatment and hemodilution. The augmented hematocrit did not compromise peak cardiac output. In summary, in healthy humans, rHuEpo increases maximal oxygen consumption due to augmented systemic and muscular peak oxygen delivery.

scholarly journals Twenty-year follow-up of aerobic power and body composition of older track athletes

1997 ◽  
Vol 82 (5) ◽  
pp. 1508-1516 ◽  
Author(s):  
Michael L. Pollock ◽  
Larry J. Mengelkoch ◽  
James E. Graves ◽  
David T. Lowenthal ◽  
Marian C. Limacher ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Body Composition ◽  
Oxygen Uptake ◽  
Bone Mineral ◽  
Maximal Oxygen Uptake ◽  
Weight Training ◽  
Aerobic Power ◽  
Mineral Density ◽  
Track Athletes

Pollock, Michael L., Larry J. Mengelkoch, James E. Graves, David T. Lowenthal, Marian C. Limacher, Carl Foster, and Jack H. Wilmore. Twenty-year follow-up of aerobic power and body composition of older track athletes. J. Appl. Physiol. 82(5): 1508–1516, 1997.—The purpose was to determine the aerobic power (maximal oxygen uptake) and body composition of older track athletes after a 20-yr follow-up (T3). At 20 yr, 21 subjects [mean ages: 50.5 ± 8.5 yr at initial evaluation (T1), 60.2 ± 8.8 yr at 10-yr follow-up (T2), and 70.4 ± 8.8 yr at 20-yr follow-up (T3)] were divided into three intensity groups: high (H; remained elite; n = 9); moderate (M; continued frequent moderate-to-rigorous endurance training; n = 10); and low (L; greatly reduced training; n = 2). All groups decreased in maximal oxygen uptake at each testing point (H, 8 and 15%; M, 13 and 14%; and L, 18 and 34% from T1 to T2 and T2 to T3, respectively). Maximal heart rate showed a linear decrease of ∼5–7 beats ⋅ min−1 ⋅ decade−1 and was independent of training status. Body weight remained stable for the H and M groups and percent fat increased ∼2–2.5%/decade. Although fat-free weight decreased at each testing point, there was a trend for those who began weight-training exercise to better maintain it. Cross-sectional analysis at T3 showed that leg strength and bone mineral density were generally maintained from age 60 to 89 yr. Those who performed weight training had a greater arm region bone mineral density than those who did not. These longitudinal data show that the physiological capacities of older athletes are reduced despite continued vigorous endurance exercise over a 20-yr period (∼8–15%/decade). Changes in body composition appeared to be less than those shown for the healthy sedentary population and were related to changes in training habits.

Time course of aerobic recovery after contraction of rabbit papillary muscle

1987 ◽  
Vol 253 (2) ◽  
pp. H325-H332 ◽  
Author(s):  
F. Mast ◽  
G. Elzinga
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Time Constant ◽  
Oxygen Consumption Rate ◽  
Time Course ◽  
Consumption Rate ◽  
Oxygen Storage ◽  
Measuring System ◽  
Measured Time ◽  
Isometric Twitch

The time course of oxygen uptake after isometric twitch contractions of isolated rabbit papillary muscles was determined at 20 degrees C by continuous polarographic measurement of the partial pressure of oxygen in a 219-microliters glass chamber in which the fluid circulated rapidly. The response time of the oxygen-measuring system was characterized by a delay of 1.1 s and a time constant of 2.1 s after that delay. Depending on the stimulation frequency (0.125–1.0 Hz) the total amount of oxygen uptake for 120 twitches varied from 5.3 to 32.7 nmol/mg dry wt, and the steady-state oxygen consumption rate varied from 0.4 to 8.5 nmol X min-1 X mg dry wt-1. On the basis of a diffusion model we eliminated the effect of oxygen storage on the measured time course of oxygen consumption to determine the mitochondrial kinetics. We found a time constant of an average 19–22 s of mitochondrial off kinetics. By use of this time constant for the change in oxygen consumption rate after contraction, it can be estimated that 9–10% of the oxygen required to restore ATP levels is already taken up by the mitochondria during the twitch.

Eighteen days of “living high, training low” stimulate erythropoiesis and enhance aerobic performance in elite middle-distance runners

2006 ◽  
Vol 100 (1) ◽  
pp. 203-211 ◽  
Author(s):  
Julien V. Brugniaux ◽  
Laurent Schmitt ◽  
Paul Robach ◽  
Gérard Nicolet ◽  
Jean-Pierre Fouillot ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Aerobic Power ◽  
Ventilatory Threshold ◽  
Maximal Aerobic Power ◽  
Aerobic Performance ◽  
Control Group ◽  
Distance Runners ◽  
Early Return ◽  
Oxygen Carrying Capacity

The efficiency of “living high, training low” (LHTL) remains controversial, despite its wide utilization. This study aimed to verify whether maximal and/or submaximal aerobic performance were modified by LHTL and whether these effects persist for 15 days after returning to normoxia. Last, we tried to elucidate whether the mechanisms involved were only related to changes in oxygen-carrying capacity. Eleven elite middle-distance runners were tested before (Pre), at the end (Post1), and 15 days after the end (Post2) of an 18-day LHTL session. Hypoxic group (LHTL, n = 5) spent 14 h/day in hypoxia (6 nights at 2,500 m and 12 nights at 3,000 m), whereas the control group (CON, n = 6) slept in normoxia (1,200 m). Both LHTL and CON trained at 1,200 m. Maximal oxygen uptake and maximal aerobic power were improved at Post1 and Post2 for LHTL only (+7.1 and +3.4% for maximal oxygen uptake, +8.4 and +4.7% for maximal aerobic power, respectively). Similarly oxygen uptake and ventilation at ventilatory threshold increased in LHTL only (+18.1 and +12.2% at Post1, +15.9 and +15.4% at Post2, respectively). Heart rate during a 10-min run at 19.5 km/h decreased for LHTL at Post2 (−4.4%). Despite the stimulation of erythropoiesis in LHTL shown by the 27.4% increase in serum transferrin receptor and the 10.1% increase in total hemoglobin mass, red cell volume was not significantly increased at Post1 (+9.2%, not significant). Therefore, both maximal and submaximal aerobic performance in elite runners were increased by LHTL mainly linked to an improvement in oxygen transport in early return to normoxia and probably to other process at Post2.

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