scholarly journals Moderate-Intensity Oxygen Uptake Kinetics: Is a Mono-Exponential Function Always Appropriate to Model the Response?

2018 ◽  
Vol 89 (3) ◽  
pp. 309-321 ◽  
Author(s):  
Julian Dale ◽  
Mark Glaister
Keyword(s):  
Oxygen Uptake ◽  
Exponential Function ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Moderate Intensity

scholarly journals Oxygen Uptake Kinetics During Arm Cranking Within The Moderate Intensity Domain

2009 ◽  
Vol 41 ◽  
pp. 116
Author(s):  
Surendran Sabapathy ◽  
Norman R. Morris ◽  
Donald A. Schneider ◽  
Donald H. Paterson
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Moderate Intensity ◽  
Arm Cranking

scholarly journals Impact of l-citrulline supplementation on oxygen uptake kinetics during walking

2018 ◽  
Vol 43 (6) ◽  
pp. 631-637 ◽  
Author(s):  
John Ashley ◽  
Youngdeok Kim ◽  
Joaquin U. Gonzales
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Oxygen Uptake ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Oxygen Deficit ◽  
Moderate Intensity ◽  
Oxygen Cost ◽  
Cohen’S D ◽  
Cohen's D

Supplementation with l-citrulline (Cit) has been shown to improve muscle oxygenation and oxygen uptake kinetics during moderate- to high-intensity cycling in young men. The aim of this study was to test the hypothesis that Cit would improve oxygen uptake kinetics during walking in older and young adults. In a randomized, double-blind study, 26 (15 women, 11 men) adults between the ages of 20–35 years (n = 15) and 64–86 years (n = 11) completed 7-day periods of taking placebo and Cit (6 g/day) in a crossover manner. Participants walked on a treadmill at 40% heart rate reserve while pulmonary oxygen uptake was measured using indirect calorimetry. Net oxygen cost, mean response time (MRT), and the oxygen deficit were calculated before and after each supplement period. There was no significant change (P > 0.05) in net oxygen cost, MRT, or the oxygen deficit after Cit in older adults, while young adults showed a decrease (P = 0.05) in the oxygen deficit after Cit that tended (P = 0.053) to be different than the change after placebo. Sex-stratified analysis revealed that Cit decreased MRT (P = 0.04, Cohen’s d = 0.41) and the oxygen deficit (P < 0.01, Cohen’s d = 0.56) in men with the change after Cit being greater than the change after placebo (MRT: −4.5 ± 2.1 vs. 3.4 ± 2.1 s, P = 0.01; deficit: −0.15 ± 0.05 vs. 0.01 ± 0.05 L, P = 0.02). All oxygen uptake parameters were unchanged (P > 0.05) following Cit and placebo in women. Cit does not alter the oxygen cost of moderate-intensity walking in young or older adults, but Cit improved the rate of rise in oxygen uptake at exercise onset in men.

scholarly journals Cocoa-flavanols enhance moderate-intensity pulmonary V̇O2 kinetics but not exercise tolerance in sedentary middle-aged adults: A randomised controlled trial

2020 ◽  
Author(s):  
Daniel Sadler ◽  
Richard Draijer ◽  
Claire E. Stewart ◽  
Helen Jones ◽  
Simon Marwood ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Exercise Tolerance ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Moderate Intensity ◽  
Moderate Activity ◽  
Middle Aged ◽  
Severe Intensity ◽  
Middle Aged Adults ◽  
Cocoa Flavanols

Abstract Background: Cocoa flavanols (CF) may exert health benefits through their potent vasodilatory effects which are perpetuated by elevations in nitric oxide (NO) bioavailability. These vasodilatory effects may contribute to improved delivery of blood and oxygen to exercising muscle.Objective: Therefore, the objective of this study was to examine how CF supplementation impacts pulmonary oxygen uptake (V̇O2) kinetics and exercise tolerance in sedentary middle-aged adults.Methods: We employed a double-blind cross-over, placebo-controlled design whereby 17 participants (11 male, 6 female; mean±SD, 45±6 years) randomly received either 7 days of daily CF (400 mg) or placebo (PL) supplementation. On day 7, participants completed a series of ‘step’ moderate- and severe-intensity exercise tests for the determination of oxygen uptake kinetics.Results: During moderate-intensity exercise, the time constant of the fundamental phase of V̇O2 kinetics (τV̇O2) was decreased by 15% in CF as compared to PL (mean±SD; PL: 40±12 vs. CF: 34±9 s, P=0.019), with no differences in the amplitude of V̇O2 (AV̇O2; PL: 0.77±0.32 vs. CF: 0.79±0.34 l min−1, P=0.263). However, during severe-intensity exercise, τV̇O2,the amplitude of the slow component (SCV̇O2) and exercise tolerance (PL: 435±58 vs. CF: 424±47 s, P=0.480) were unchanged between conditions.Conclusions: Our data show that acute CF supplementation enhanced oxygen uptake kinetics during moderate-, but not severe-intensity exercise in middle-aged participants. These novel effects of CFs, in this demographic, may contribute to improved tolerance of moderate-activity physical activities, which appear commonly present in daily life.Registered under ClinicalTrials.gov Identifier no. NCT04370353

Muscle phosphocreatine and pulmonary oxygen uptake kinetics in children at the onset and offset of moderate intensity exercise

2008 ◽  
Vol 102 (6) ◽  
pp. 727-738 ◽  
Author(s):  
Alan R. Barker ◽  
Joanne R. Welsman ◽  
Jonathan Fulford ◽  
Deborah Welford ◽  
Craig A. Williams ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Pulmonary Oxygen Uptake

Oxygen uptake kinetics in children and adults after the onset of moderate-intensity exercise

2002 ◽  
Vol 20 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Samantha G. Fawkner ◽  
Neil Armstrong ◽  
Christopher R. Potter ◽  
Joanne R. Welsman
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise

Effects of acute hypoxia on the oxygen uptake kinetics of older adults during cycling exercise

2012 ◽  
Vol 37 (4) ◽  
pp. 744-752 ◽  
Author(s):  
Livio Zerbini ◽  
Alfredo Brighenti ◽  
Barbara Pellegrini ◽  
Lorenzo Bortolan ◽  
Tommaso Antonetti ◽  
...  
Keyword(s):  
Older Adults ◽  
Oxygen Uptake ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Moderate Intensity ◽  
Vastus Lateralis Muscle ◽  
Incremental Test ◽  
Square Wave

Pulmonary oxygen uptake, heart rate (HR), and deoxyhemoglobin (HHb) kinetics were studied in a group of older adults exercising in hypoxic conditions. Fourteen healthy older adults (aged 66 ± 6 years) performed 4 exercise sessions that consisted of (i) an incremental test to exhaustion on a cycloergometer while breathing normoxic room air (fractional inspired oxygen (FiO2) = 20.9% O2); (ii) an incremental test to exhaustion on a cycloergometer while breathing hypoxic room air (FiO2 = 15% O2); (iii) 3 repeated square wave cycling exercises at moderate intensity while breathing normoxic room air; and (iv) 3 repeated square wave cycling exercises at moderate intensity while breathing hypoxic room air. During all exercise sessions, pulmonary gas exchange was measured breath-by-breath; HHb was determined on the vastus lateralis muscle by near-infrared spectroscopy; and HR was collected beat-by-beat. The pulomary oxygen uptake kinetics became slower in hypoxia (31 ± 9 s) than in normoxia (27 ± 7 s) because of an increased mismatching between O2 delivery to O2 utilization at the level of the muscle. The HR and HHb kinetics did not change between hypoxia and normoxia,

scholarly journals Data collection, handling, and fitting strategies to optimize accuracy and precision of oxygen uptake kinetics estimation from breath-by-breath measurements

2017 ◽  
Vol 123 (1) ◽  
pp. 227-242 ◽  
Author(s):  
Alan P. Benson ◽  
T. Scott Bowen ◽  
Carrie Ferguson ◽  
Scott R. Murgatroyd ◽  
Harry B. Rossiter
Keyword(s):  
Data Collection ◽  
Oxygen Uptake ◽  
Comparative Studies ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Moderate Intensity ◽  
Optimum Number ◽  
Minimally Important Difference ◽  
Accuracy And Precision ◽  
Fitting Procedures

Phase 2 pulmonary oxygen uptake kinetics (ϕ2 τV̇o2P) reflect muscle oxygen consumption dynamics and are sensitive to changes in state of training or health. This study identified an unbiased method for data collection, handling, and fitting to optimize V̇o2P kinetics estimation. A validated computational model of V̇o2P kinetics and a Monte Carlo approach simulated 2 × 105 moderate-intensity transitions using a distribution of metabolic and circulatory parameters spanning normal health. Effects of averaging (interpolation, binning, stacking, or separate fitting of up to 10 transitions) and fitting procedures (biexponential fitting, or ϕ2 isolation by time removal, statistical, or derivative methods followed by monoexponential fitting) on accuracy and precision of V̇o2P kinetics estimation were assessed. The optimal strategy to maximize accuracy and precision of τV̇o2P estimation was 1-s interpolation of 4 bouts, ensemble averaged, with the first 20 s of exercise data removed. Contradictory to previous advice, we found optimal fitting procedures removed no more than 20 s of ϕ1 data. Averaging method was less critical: interpolation, binning, and stacking gave similar results, each with greater accuracy compared with analyzing repeated bouts separately. The optimal procedure resulted in ϕ2 τV̇o2P estimates for transitions from an unloaded or loaded baseline that averaged 1.97 ± 2.08 and 1.04 ± 2.30 s from true, but were within 2 s of true in only 47–62% of simulations. Optimized 95% confidence intervals for τV̇o2P ranged from 4.08 to 4.51 s, suggesting a minimally important difference of ~5 s to determine significant changes in τV̇o2P during interventional and comparative studies. NEW & NOTEWORTHY We identified an unbiased method to maximize accuracy and precision of oxygen uptake kinetics (τV̇o2P) estimation. The optimum number of bouts to average was four; interpolation, bin, and stacking averaging methods gave similar results. Contradictory to previous advice, we found that optimal fitting procedures removed no more than 20 s of phase 1 data. Our data suggest a minimally important difference of ~5 s to determine significant changes in τV̇o2P during interventional and comparative studies.

scholarly journals Pulmonary O2 uptake on-kinetics in sprint- and endurance-trained athletes

2007 ◽  
Vol 32 (3) ◽  
pp. 383-393 ◽  
Author(s):  
Nicolas J.A. Berger ◽  
Andrew M. Jones
Keyword(s):  
Oxygen Uptake ◽  
Phase Ii ◽  
Exercise Performance ◽  
Slow Component ◽  
Oxygen Uptake Kinetics ◽  
Uptake Kinetics ◽  
Anaerobic Exercise ◽  
Moderate Intensity ◽  
Peak Power Output ◽  
Severe Intensity

Pulmonary O2 uptake kinetics during “step” exercise have not been characterized in young, sprint-trained (SPT), athletes. Therefore, the objective of this study was to test the hypotheses that SPT athletes would have (i) slower phase II kinetics and (ii) a greater oxygen uptake “slow component” when compared with endurance-trained (ENT) athletes. Eight sub-elite SPT athletes (mean ( ± SD) age = 25 (±7) y; mass = 80.3 (±7.3) kg) and 8 sub-elite ENT athletes (age= 28 (±4) y; mass = 73.2 (±5.1) kg) completed a ramp incremental cycle ergometer test, a Wingate 30 s anaerobic sprint test, and repeat “step” transitions in work rate from 20 W to moderate- and severe-intensity cycle exercise, during which pulmonary oxygen uptake was measured breath by breath. The phase II oxygen uptake kinetics were significantly slower in the SPT athletes both for moderate (time constant, τ; SPT 32 (±4) s vs. ENT 17 (±3) s; p < 0.01) and severe (SPT 32 (±12) s vs. ENT 20 (±6) s; p < 0.05) exercise. The amplitude of the slow component (derived by exponential modelling) was not significantly different between the groups (SPT 0.55 (±0.12) L·min–1 vs. ENT 0.50 (±0.22) L·min–1), but the increase in oxygen uptake between 3 and 6 min of severe exercise was greater in the SPT athletes (SPT 0.37 (±0.08) L·min–1 vs. ENT 0.20 (±0.09) L·min–1; p < 0.01). The phase II τ was significantly correlated with indices of aerobic exercise performance (e.g., peak oxygen uptake (moderate-intensity r = –0.88, p < 0.01; severe intensity r = –0.62; p < 0.05), whereas the relative amplitude of the oxygen uptake slow component was significantly correlated with indices of anaerobic exercise performance (e.g., Wingate peak power output; r = 0.77; p < 0.01). Thus, it could be concluded that sub-elite SPT athletes have slower phase II oxygen uptake kinetics and a larger oxygen uptake slow component compared with sub-elite ENT athletes. It appears that indices of aerobic and anaerobic exercise performance differentially influence the fundamental and slow components of the oxygen uptake kinetics.

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