Kinetics of O2 uptake, leg blood flow, and muscle deoxygenation are slowed in the upper compared with lower region of the moderate-intensity exercise domain

2005 ◽  
Vol 99 (5) ◽  
pp. 1822-1834 ◽  
Author(s):  
Shelley L. MacPhee ◽  
J. Kevin Shoemaker ◽  
Donald H. Paterson ◽  
John M. Kowalchuk
Keyword(s):  
Blood Flow ◽  
Knee Extension ◽  
Single Step ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Leg Blood Flow ◽  
Muscle Deoxygenation ◽  
Knee Extension Exercise ◽  
Kinetics Of ◽  
Male Subjects

Six male subjects [23 yr (SD 4)] performed repetitions (6–8) of two-legged, moderate-intensity, knee-extension exercise during two separate protocols that included step transitions from 3 W to 90% estimated lactate threshold (θL) performed as a single step (S3) and in two equal steps (S1, 3 W to ∼45% θL; S2, ∼45% θL to ∼90% θL). The time constants (τ) of pulmonary oxygen uptake (V̇o2), leg blood flow (LBF), heart rate (HR), and muscle deoxygenation (HHb) were greater ( P < 0.05) in S2 (τV̇o2, ∼52 s; τLBF, ∼ 39 s; τHR, ∼42 s; τHHb, ∼33 s) compared with S1 (τV̇o2, ∼24 s; τLBF, ∼21 s; τHR, ∼21 s; τHHb, ∼16 s), while the delay before an increase in HHb was reduced ( P < 0.05) in S2 (∼14 s) compared with S1 (∼20 s). The V̇o2 and HHb amplitudes were greater ( P < 0.05) in S2 compared with S1, whereas the LBF amplitude was similar in S2 and S1. Thus the slowed V̇o2 response in S2 compared with S1 is consistent with a mechanism whereby V̇o2 kinetics is limited, in part, by a slowed adaptation of blood flow and/or O2 transport when exercise was initiated from a baseline of moderate-intensity exercise.

The effect of hypoxia on pulmonary O2uptake, leg blood flow and muscle deoxygenation during single-leg knee-extension exercise

2004 ◽  
Vol 89 (3) ◽  
pp. 293-302 ◽  
Author(s):  
Darren S. DeLorey ◽  
Colin N. Shaw ◽  
J. Kevin Shoemaker ◽  
John M. Kowalchuk ◽  
Donald H. Paterson
Keyword(s):  
Blood Flow ◽  
Knee Extension ◽  
Leg Blood Flow ◽  
Muscle Deoxygenation ◽  
Knee Extension Exercise

Effect of short-term high-intensity interval training vs. continuous training on O2 uptake kinetics, muscle deoxygenation, and exercise performance

2009 ◽  
Vol 107 (1) ◽  
pp. 128-138 ◽  
Author(s):  
Bryon R. McKay ◽  
Donald H. Paterson ◽  
John M. Kowalchuk
Keyword(s):  
Blood Flow ◽  
High Intensity ◽  
Microvascular Blood Flow ◽  
Moderate Intensity ◽  
Vastus Lateralis Muscle ◽  
Lower Intensity ◽  
Moderate Intensity Exercise ◽  
Muscle Deoxygenation ◽  
High Intensity Interval ◽  
Kinetics Of

The early time course of adaptation of pulmonary O2 uptake (V̇o2p) (reflecting muscle O2 consumption) and muscle deoxygenation kinetics (reflecting the rate of O2 extraction) were examined during high-intensity interval (HIT) and lower-intensity continuous endurance (END) training. Twelve male volunteers underwent eight sessions of either HIT (8–12 × 1-min intervals at 120% maximal O2 uptake separated by 1 min of rest) or END (90–120 min at 65% maximal O2 uptake). Subjects completed step transitions to a moderate-intensity work rate (∼90% estimated lactate threshold) on five occasions throughout training, and ramp incremental and constant-load performance tests were conducted at pre-, mid-, and posttraining periods. V̇o2p was measured breath-by-breath by mass spectrometry and volume turbine. Deoxygenation (change in deoxygenated hemoglobin concentration; Δ[HHb]) of the vastus lateralis muscle was monitored by near-infrared spectroscopy. The fundamental phase II time constants for V̇o2p (τV̇o2) and deoxygenation kinetics {effective time constant, τ′ = (time delay + τ), Δ[HHb]} during moderate-intensity exercise were estimated using nonlinear least-squares regression techniques. The τV̇o2 was reduced by ∼20% ( P < 0.05) after only two training sessions and by ∼40% ( P < 0.05) after eight training sessions (i.e., posttraining), with no differences between HIT and END. The τ′Δ[HHb] (∼20 s) did not change over the course of eight training sessions. These data suggest that faster activation of muscle O2 utilization is an early adaptive response to both HIT and lower-intensity END training. That Δ[HHb] kinetics (a measure of fractional O2 extraction) did not change despite faster V̇o2p kinetics suggests that faster kinetics of muscle O2 utilization were accompanied by adaptations in local muscle (microvascular) blood flow and O2 delivery, resulting in a similar “matching” of blood flow to O2 utilization. Thus faster kinetics of V̇o2p during the transition to moderate-intensity exercise occurs after only 2 days HIT and END training and without changes to muscle deoxygenation kinetics, suggesting concurrent adaptations to microvascular perfusion.

Kinetics of V̇o2 and femoral artery blood flow during heavy-intensity, knee-extension exercise

2005 ◽  
Vol 99 (2) ◽  
pp. 683-690 ◽  
Author(s):  
Nicole D. Paterson ◽  
John M. Kowalchuk ◽  
Donald H. Paterson
Keyword(s):  
Blood Flow ◽  
Femoral Artery ◽  
Time Course ◽  
Slow Component ◽  
Knee Extension ◽  
Artery Blood Flow ◽  
Phase 2 ◽  
Femoral Artery Blood Flow ◽  
Knee Extension Exercise ◽  
Kinetics Of

It has been suggested that, during heavy-intensity exercise, O2 delivery may limit oxygen uptake (V̇o2) kinetics; however, there are limited data regarding the relationship of blood flow and V̇o2 kinetics for heavy-intensity exercise. The purpose was to determine the exercise on-transient time course of femoral artery blood flow (Q̇leg) in relation to V̇o2 during heavy-intensity, single-leg, knee-extension exercise. Five young subjects performed five to eight repeats of heavy-intensity exercise with measures of breath-by-breath pulmonary V̇o2 and Doppler ultrasound femoral artery mean blood velocity and vessel diameter. The phase 2 time frame for V̇o2 and Q̇leg was isolated and fit with a monoexponent to characterize the amplitude and time course of the responses. Amplitude of the phase 3 response was also determined. The phase 2 time constant for V̇o2 of 29.0 s and time constant for Q̇leg of 24.5 s were not different. The change (Δ) in V̇o2 response to the end of phase 2 of 0.317 l/min was accompanied by a ΔQ̇leg of 2.35 l/min, giving a ΔQ̇leg-to-ΔV̇o2 ratio of 7.4. A slow-component V̇o2 of 0.098 l/min was accompanied by a further Q̇leg increase of 0.72 l/min (ΔQ̇leg-to-ΔV̇o2 ratio = 7.3). Thus the time course of Q̇leg was similar to that of muscle V̇o2 (as measured by the phase 2 V̇o2 kinetics), and throughout the on-transient the amplitude of the Q̇leg increase achieved (or exceeded) the Q̇leg-to-V̇o2 ratio steady-state relationship (ratio ∼4.9). Additionally, the V̇o2 slow component was accompanied by a relatively large rise in Q̇leg, with the increased O2 delivery meeting the increased V̇o2. Thus, in heavy-intensity, single-leg, knee-extension exercise, the amplitude and kinetics of blood flow to the exercising limb appear to be closely linked to the V̇o2 kinetics.

The Adaptation Of Pulmonary O2 Uptake, Limb Blood Flow, And Muscle Deoxygenation During The Off-transient Of Moderate-intensity Exercise

2005 ◽  
Vol 37 (Supplement) ◽  
pp. S449
Author(s):  
Gregory R. duManoir ◽  
Darren S. DeLorey ◽  
Aaron P. Heenan ◽  
John M. Kowalchuk ◽  
Donald H. Paterson
Keyword(s):  
Blood Flow ◽  
Moderate Intensity ◽  
Limb Blood Flow ◽  
O2 Uptake ◽  
Moderate Intensity Exercise ◽  
Muscle Deoxygenation

Effects of prior heavy-intensity exercise on oxygen uptake and muscle deoxygenation kinetics of a subsequent heavy-intensity cycling and knee-extension exercise

2012 ◽  
Vol 37 (1) ◽  
pp. 138-148 ◽  
Author(s):  
Sarah Margaret Cleland ◽  
Juan Manuel Murias ◽  
John Michael Kowalchuk ◽  
Donald Hugh Paterson
Keyword(s):  
Oxygen Uptake ◽  
Response Time ◽  
Slow Component ◽  
Knee Extension ◽  
Phase 2 ◽  
Mean Response Time ◽  
Muscle Deoxygenation ◽  
Component Amplitude ◽  
Knee Extension Exercise ◽  
Kinetics Of

This study examined the effects of prior heavy-intensity exercise on the adjustment of pulmonary oxygen uptake (VO2p) and muscle deoxygenation Δ[HHb] during the transition to subsequent heavy-intensity cycling (CE) or knee-extension (KE) exercise. Nine young adults (aged 24 ± 5 years) performed 4 repetitions of repeated bouts of heavy-intensity exercise separated by light-intensity CE and KE, which included 6 min of baseline exercise, a 6-min step of heavy-intensity exercise (H1), 6-min recovery, and a 6-min step of heavy-intensity exercise (H2). Exercise was performed at 50 r·min–1 or contractions per minute per leg. Oxygen uptake (VO2) mean response time was ∼20% faster (p < 0.05) during H2 compared with H1 in both modalities. Phase 2 time constants (τ) were not different between heavy bouts of CE (H1, 29.6 ± 6.5 s; H2, 28.0 ± 4.6 s) or KE exercise (H1, 31.6 ± 6.7 s; H2, 29.8 ± 5.6 s). The VO2 slow component amplitude was lower (p < 0.05) in H2 in both modalities (CE, 0.19 ± 0.06 L·min–1; KE, 0.12 ± 0.07 L·min–1) compared with H1 (CE, 0.29 ± 0.09 L·min–1; KE, 0.18 ± 0.07 L·min–1), with the contribution of the slow component to the total VO2 response reduced (p < 0.05) in H2 during both exercise modes. The effective τHHb was similar between bouts for CE (H1, 18.2 ± 3.0 s; H2, 18.0 ± 3.6 s) and KE exercise (H1, 26.0 ± 7.0 s; H2, 24.0 ± 5.8 s). The ΔHHb slow component was reduced during H2 in both CE and KE (p < 0.05). In conclusion, phase 2 VO2p was unchanged with priming exercise; however, a faster mean response time of VO2p during the heavy-intensity exercise preceded by a priming heavy-intensity exercise was attributed to a smaller slow component and reduced muscle deoxygenation indicative of improved muscle O2 delivery during the second bout of exercise.

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