Slow component of O2 uptake during heavy exercise: adaptation to endurance training (original) (raw)
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Journal of Applied Physiology, 2014
The purpose of this study was to test the hypothesis that V̇o2 kinetics would be speeded to a greater extent following repeated sprint training (RST), compared with continuous endurance training (ET), in the transition from moderate- to severe-intensity exercise. Twenty-three recreationally active subjects were randomly assigned to complete six sessions of ET (60–110 min of moderate-intensity cycling) or RST (four to seven 30-s all-out Wingate tests) over a 2-wk period. Subjects completed three identical work-to-work cycling exercise tests before and after the intervention period, consisting of baseline cycling at 20 W followed by sequential step increments to moderate- and severe-intensity work rates. The severe-intensity bout was continued to exhaustion on one occasion and was followed by a 60-s all-out sprint on another occasion. Phase II pulmonary V̇o2 kinetics were speeded by a similar magnitude in both the lower (ET pre, 28 ± 4; ET post, 22 ± 4 s; RST pre, 25 ± 8; RST post, 20...
VO(2) kinetics and the O(2) deficit in heavy exercise
Journal of applied physiology (Bethesda, Md. : 1985), 2000
The purpose of this study was to examine a new method for calculating the O(2) deficit that considered the O(2) uptake (VO(2)) kinetics during exercise as two separate phases in light of previous research in which it was shown that the traditional O(2) deficit calculation overestimated the recovery O(2) consumption (ROC). Eight subjects completed exercise transitions between unloaded cycling and 25% (heavy, H) or 50% (very heavy, VH) of the difference between the lactic acid threshold (LAT) and peak VO(2) for 8 min. The O(2) deficit, calculated in the traditional manner, was significantly greater than the measured ROC for both above-LAT exercises: 4.03 +/- 1.01 vs. 2.63 +/- 0.80 (SD) liters for VH and 2.36 +/- 0.91 vs. 1.74 +/- 0.63 liters for H for the O(2) deficit vs. ROC (P < 0.05). When the kinetics were viewed as two separate components with independent onsets, the calculated O(2) deficit (2.89 +/- 0.79 and 1.71 +/- 0.70 liters for VH and H, respectively) was not different f...
Journal of Applied Physiology, 2005
The effect of prior heavy-intensity warm-up exercise on subsequent moderate-intensity phase 2 pulmonary O2 uptake kinetics (τV̇o2) was examined in young adults exhibiting relatively fast (FK; τV̇o2 < 30 s; n = 6) and slow (SK; τV̇o2 > 30 s; n = 6) V̇o2 kinetics in moderate-intensity exercise without prior warm up. Subjects performed four repetitions of a moderate (Mod1)-heavy-moderate (Mod2) protocol on a cycle ergometer with work rates corresponding to 80% estimated lactate threshold (moderate intensity) and 50% difference between lactate threshold and peak V̇o2 (heavy intensity); each transition lasted 6 min, and each was preceded by 6 min of cycling at 20 W. V̇o2 and heart rate (HR) were measured breath-by-breath and beat-by-beat, respectively; concentration changes of muscle deoxyhemoglobin (HHb), oxyhemoglobin, and total hemoglobin were measured by near-infrared spectroscopy (Hamamatsu NIRO 300). τV̇o2 was lower ( P < 0.05) in Mod2 than in Mod1 in both FK (20 ± 5 s vs....
Journal of Applied Physiology, 2010
The time course and mechanisms of adjustment of pulmonary oxygen uptake (V̇o2) kinetics (time constant τV̇o2p) were examined during step transitions from 20 W to moderate-intensity cycling in eight older men (O; 68 ± 7 yr) and eight young men (Y; 23 ± 5 yr) before training and at 3, 6, 9, and 12 wk of endurance training. V̇o2p was measured breath by breath with a volume turbine and a mass spectrometer. Changes in deoxygenated hemoglobin concentration (Δ[HHb]) were measured by near-infrared spectroscopy. V̇o2p and Δ[HHb] were modeled with a monoexponential model. Training was performed on a cycle ergometer three times per week for 45 min at ∼70% of peak V̇o2. Pretraining τV̇o2p was greater ( P < 0.05) in O (43 ± 10 s) than Y (34 ± 8 s). τV̇o2p decreased ( P < 0.05) by 3 wk of training in both O (35 ± 9 s) and Y (22 ± 8 s), with no further changes thereafter. The pretraining overall adjustment of Δ[HHb] was faster than τV̇o2p in both O and Y, resulting in Δ[HHb]/V̇o2p displaying...
O2 uptake kinetics during exercise at peak O2 uptake
Journal of applied physiology (Bethesda, Md. : 1985), 2003
Compared with moderate- and heavy-intensity exercise, the adjustment of O2 uptake (VO2) to exercise intensities that elicit peak VO2 has received relatively little attention. This study examined the VO2 response of 21 young, healthy subjects (25 +/- 6 yr; mean +/- SD) during cycle ergometer exercise to step transitions in work rate (WR) corresponding to 90, 100, and 110% of the peak WR achieved during a preliminary ramp protocol (15-30 W/min). Gas exchange was measured breath by breath and interpolated to 1-s values. VO2 kinetics were determined by use of a two- or three-component exponential model to isolate the time constant (tau2) as representative of VO2 kinetics and the amplitude (Amp) of the primary fast component independent of the appearance of any VO2 slow component. No difference in VO2 kinetics was observed between WRs (tau90 = 24.7 +/- 9.0; tau100 = 22.8 +/- 6.7; tau110 = 21.5 +/- 9.2 s, where subscripts denote percent of peak WR; P > 0.05); nor in a subgroup of eight...
2005
Few studies have investigated the influence of hypoxia on the primary and the slow components [10, 23] of oxygen uptake (V Ç O 2 ) kinetics. Regarding the primary component, a consensus in the literature does exist. A slower V Ç O 2 kinetics (that is a longer primary component time constant t) has been always reported under moderate hypoxia (inspired gas concentration or FIO 2 < 0.15) compared with normoxia at the same absolute work rate for both moderate (< ventilatory threshold, VT) and heavy (> VT) exercise intensities . Based on the relationship between O 2 supply in working muscles and V Ç O 2 kinetics, some authors have concluded that the mechanisms determining the V Ç O 2 -response at the onset of constant work-rate heavy exercise would be related to the rate of O 2 delivery to the working muscles. However, others suggested that the Abstract This study examined the influence of moderate hypoxia on the oxygen uptake (V Ç O 2 ) kinetic response (primary time constant and slow component amplitude) during moderate and heavy cycle exercise in twenty-seven male subjects with various training status. Nine endurance trained (21.5 2.6 yr), nine sprint trained (22.9 5.7 yr), and nine untrained controls (24.0 4.4 yr) completed incremental tests to exhaustion in normoxia (inspired gas concentration or FIO 2 = 21% O 2 ) and hypoxia (FIO 2 = 13% O 2 ) to establish the FIO 2 -specific ventilatory threshold (VT) and maximal VO 2 . Subsequently, the subjects performed repeated constant work rate cycling exercises during 7 min at moderate intensity (80 % of FIO 2 -specific VT) and heavy intensity (midway between the FIO 2 specific VT and maximal VO 2 ). Pulmonary gas exchange was measured breath-by-breath during all exercise sessions. For both moderate and heavy intensities, the time constant of the primary VO 2 component was significantly (p < 0.05) slowed by~25 to 30 % in hypoxia compared to normoxia to the same extent in the three groups. Hypoxia produced a more important decrease in the amplitude of the slow component in endurance athletes (± 36%) than in sprinters (± 30 %) and controls (± 12%). These results suggest that both primary and slow components of VO 2 kinetics during the adjustment to moderateand heavy-intensity exercise are sensitive to hypoxia while training status tended to modulate partly the slow component amplitude.
Medicine & Science in Sports & Exercise, 1998
NT. Temporal changes in blood lactate (r=0.40) and ventilation (r=0.72) were significantly correlated with the changes for SC over the 6 wk training period (p<0.05). In conclusion, training at supra-LT and sub-LT intensities produces similar improvement in VO 2 and power output at peak exercise and in the LT, when total work output is held constant. However, training at supra-LT intensity promotes larger and faster adaptations in the SC than training at the sub-LT levels.
European Journal of Applied Physiology, 2014
10.7 mmol L −1 , respectively), VO 2 baseline (0.74 versus 0.93 L min −1 , respectively) and the heart rate (HR; 102 versus 124 bpm, respectively) before the onset of highintensity exercise. However, both prior CE and prior IRS significantly increased the absolute primary VO 2 amplitude (3.77 and 3.79 L min −1 , respectively, versus control 3.54 L min −1 ), reduced the amplitude of the VO 2 slow component (0.26 and 0.21 L min −1 , respectively, versus control 0.50 L min −1 ), and decreased the mean response time (MRT; 28.9 and 28.0 s, respectively, versus control 36.9 s) during subsequent bouts. Conclusion This study showed that different protocols and intensities of prior exercise trigger similar effects on VO 2 kinetics during high-intensity running.