Pulmonary O2 uptake kinetics as a determinant of high-intensity exercise tolerance in humans

2011 ◽  
Vol 110 (6) ◽  
pp. 1598-1606 ◽  
Author(s):  
Scott R. Murgatroyd ◽  
Carrie Ferguson ◽  
Susan A. Ward ◽  
Brian J. Whipp ◽  
Harry B. Rossiter
Keyword(s):  
Steady State ◽  
High Intensity ◽  
Exercise Tolerance ◽  
Slow Component ◽  
Progressive Increase ◽  
High Intensity Exercise ◽  
Exercise Intolerance ◽  
Exercise Onset ◽  
O2 Uptake Kinetics ◽  
Two Parameters

Tolerance to high-intensity constant-power (P) exercise is well described by a hyperbola with two parameters: a curvature constant (W′) and power asymptote termed “critical power” (CP). Since the ability to sustain exercise is closely related to the ability to meet the ATP demand in a steady state, we reasoned that pulmonary O2 uptake (V̇o2) kinetics would relate to the P-tolerable duration (tlim) parameters. We hypothesized that 1) the fundamental time constant (τV̇o2) would relate inversely to CP; and 2) the slow-component magnitude (ΔV̇o2sc) would relate directly to W′. Fourteen healthy men performed cycle ergometry protocols to the limit of tolerance: 1) an incremental ramp test; 2) a series of constant-P tests to determine V̇o2max, CP, and W′; and 3) repeated constant-P tests (WR6) normalized to a 6 min tlim for τV̇o2 and ΔV̇o2sc estimation. The WR6 tlim averaged 365 ± 16 s, and V̇o2max (4.18 ± 0.49 l/min) was achieved in every case. CP (range: 171–294 W) was inversely correlated with τV̇o2 (18–38 s; R2 = 0.90), and W′ (12.8–29.9 kJ) was directly correlated with ΔV̇o2sc (0.42–0.96 l/min; R2 = 0.76). These findings support the notions that 1) rapid V̇o2 adaptation at exercise onset allows a steady state to be achieved at higher work rates compared with when V̇o2 kinetics are slower; and 2) exercise exceeding this limit initiates a “fatigue cascade” linking W′ to a progressive increase in the O2 cost of power production (V̇o2sc), which, if continued, results in attainment of V̇o2max and exercise intolerance. Collectively, these data implicate V̇o2 kinetics as a key determinant of high-intensity exercise tolerance in humans.

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.

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.

Acceleration of V˙o 2kinetics in heavy submaximal exercise by hyperoxia and prior high-intensity exercise

1997 ◽  
Vol 83 (4) ◽  
pp. 1318-1325 ◽  
Author(s):  
Maureen Macdonald ◽  
Preben K. Pedersen ◽  
Richard L. Hughson
Keyword(s):  
High Intensity ◽  
Ventilatory Threshold ◽  
Slow Component ◽  
Submaximal Exercise ◽  
High Intensity Exercise ◽  
Total Change ◽  
Group Of Seven ◽  
Mean Response Time ◽  
Exercise Transitions ◽  
The Mean

MacDonald, Maureen, Preben K. Pedersen, and Richard L. Hughson. Acceleration ofV˙o 2 kinetics in heavy submaximal exercise by hyperoxia and prior high-intensity exercise. J. Appl. Physiol. 83(4): 1318–1325, 1997.—We examined the hypothesis that O2 uptake (V˙o 2) would change more rapidly at the onset of step work rate transitions in exercise with hyperoxic gas breathing and after prior high-intensity exercise. The kinetics ofV˙o 2 were determined from the mean response time (MRT; time to 63% of total change inV˙o 2) and calculations of O2 deficit and slow component during normoxic and hyperoxic gas breathing in one group of seven subjects during exercise below and above ventilatory threshold (VT) and in another group of seven subjects during exercise above VT with and without prior high-intensity exercise. In exercise transitions below VT, hyperoxic gas breathing did not affect the kinetic response of V˙o 2 at the onset or end of exercise. At work rates above VT, hyperoxic gas breathing accelerated both the on- and off-transient MRT, reduced the O2 deficit, and decreased theV˙o 2 slow component from minute 3 to minute 6 of exercise, compared with normoxia. Prior exercise above VT accelerated the on-transient MRT and reduced theV˙o 2 slow component from minute 3 to minute 6 of exercise in a second bout of exercise with both normoxic and hyperoxic gas breathing. However, the summated O2 deficit in the second normoxic and hyperoxic steps was not different from that of the first steps in the same gas condition. Faster on-transient responses in exercise above, but not below, VT with hyperoxia and, to a lesser degree, after prior high-intensity exercise above VT support the theory of an O2 transport limitation at the onset of exercise for workloads >VT.

Effects of prior very-heavy intensity exercise on indices of aerobic function and high-intensity exercise tolerance

2007 ◽  
Vol 103 (3) ◽  
pp. 812-822 ◽  
Author(s):  
C. Ferguson ◽  
B. J. Whipp ◽  
A. J. Cathcart ◽  
H. B. Rossiter ◽  
A. P. Turner ◽  
...  
Keyword(s):  
High Intensity ◽  
Slow Component ◽  
Energy Resource ◽  
Constant Load ◽  
High Intensity Exercise ◽  
Metabolite Level ◽  
Fully Depleted ◽  
Significant Difference ◽  
Aerobic Function ◽  
Residual Fatigue

A recent bout of high-intensity exercise can alter the balance of aerobic and anaerobic energy provision during subsequent exercise above the lactate threshold (θL). However, it remains uncertain whether such “priming” influences the tolerable duration of subsequent exercise through changes in the parameters of aerobic function [e.g., θL, maximum oxygen uptake (V̇o2max)] and/or the hyperbolic power-duration (P-t) relationship [critical power (CP) and the curvature constant (W′)]. We therefore studied six men performing cycle ergometry to the limit of tolerance; gas exchange was measured breath-by-breath and arterialized capillary blood [lactate] was measured at designated intervals. On different days, each subject completed 1) an incremental test (15 W/min) for estimation of θL and measurement of the functional gain (ΔV̇o2/ΔWR) and V̇o2peak and 2) four constant-load tests at different work rates (WR) for estimation of CP, W′, and V̇o2max. All tests were subsequently repeated with a preceding 6-min supra-CP priming bout and an intervening 2-min 20-W recovery. The hyperbolicity of the P-t relationship was retained postpriming, with no significant difference in CP (241 ± 39 vs. 242 ± 36 W, post- vs. prepriming), V̇o2max (3.97 ± 0.34 vs. 3.93 ± 0.38 l/min), ΔV̇o2/ΔWR (10.7 ± 0.3 vs. 11.1 ± 0.4 ml·min−1·W−1), or the fundamental V̇o2 time constant (25.6 ± 3.5 vs. 28.3 ± 5.4 s). W′ (10.61 ± 2.07 vs. 16.13 ± 2.33 kJ) and the tolerable duration of supra-CP exercise (−33 ± 11%) were each significantly reduced, despite a less-prominent V̇o2 slow component. These results suggest that, following supra-CP priming, there is either a reduced depletable energy resource or a residual fatigue-metabolite level that leads to the tolerable limit before this resource is fully depleted.

Late Exercise Tolerance Testing Using a Dynamic High Intensity Interval Multidirectional Movement Protocol

Neurology ◽  
2021 ◽  
Vol 98 (1 Supplement 1) ◽  
pp. S8.1-S8
Author(s):  
Mohammad Mortazavi ◽  
Katelyn Paulsen ◽  
Tyler R. Marx ◽  
Monica Pita Other ◽  
Luke Muratalla Maes, Other ◽  
...  
Keyword(s):  
Exercise Testing ◽  
High Intensity ◽  
Exercise Tolerance ◽  
Late Phase ◽  
Force Plate ◽  
Retrospective Chart Review ◽  
Exercise Intolerance ◽  
Post Exercise ◽  
Average Change ◽  
High Intensity Interval

ObjectiveAnalyze the utility of a 5-step exertional rehab protocol (ERP) that included High Intensity Interval Multi-Directional Movement (HIIT-MD) or step 5. We assessed the incidence and etiologies of exercise intolerance (EI) during Step 5 in concussed patients who tolerated maximal linear exertion.BackgroundExertional testing can be used to determine appropriate levels of exercise tolerance (ET) in concussed patients. Traditionally linear modalities have been used to determine max ET prior to clearance. HIIT-MD protocols can be the next appropriate step to bridge clearance for more dynamic activities.Design/MethodsRetrospective chart review included 130 step 5 trials for EI; of those, 72 had pre/postexercise King Devick (KD) and force plate (FP) testing. Patients were 10–59 years old and clinic visits occurred 2019–2020. EI rate was recorded and failure reason was documented by our clinic's concussion specialist. The difference between pre/post exercise KD and FP was investigated.ResultsOf 130 step 5 trials, 21.54% failed due to EI. Reason for EI included the onset of symptoms (82.1%), followed by signs of dysautonomia (39.3%). Symptoms and dysautonomia combined were noted in 35.7% of those with EI. Symptoms appeared in combination with another marker 69.6% of the time. The average change in KD times pre/post exercise testing was +2.52 seconds longer in the EI group compared to −2.45 seconds shorter in the ET group (p = 0.62). The EI group demonstrated an average change of 0.36 deg/sec sway velocity increase after exercise compared to 0.13 deg/sec in the ET group (p = 0.93).ConclusionsThere is evidence for the utility of a HITT-MD protocol for dynamic exercise/sports clearance. Exercise testing progression and concussion clearance should include a dynamic HITT-MD protocol to ascertain no late phase dynamic EI. Dysautonomia and/or vestibulocular aggravation may be contributors to late phase EI. If EI exists, identifying and targeting underlying causes can aid optimal recovery.

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