Cardiovascular and Oxygen Uptake Kinetics During Sequential Heavy Cycling Exercises

The purpose of the present study was to assess the relationship between the rapidity of increased oxygen uptake [Formula: see text] and increased cardiac output (CO) during heavy exercise. Six subjects performed repeated bouts on a cycle ergometer above the ventilatory threshold (∼80% of peak [Formula: see text]) separated by 10-min recovery cycling at 35% peak [Formula: see text]. [Formula: see text] was determined breath-by-breath and CO was determined continuously by impedance cardiography. CO and [Formula: see text] values were significantly higher during the 2-min period preceding the second bout. The overall responses for [Formula: see text] and CO were significantly related and were faster during the second bout. Prior heavy exercise resulted in a significant increase in the amplitude of the fast component of [Formula: see text] with no change in the time constant and a decrease in the slow component. Under these circumstances, the amplitude of the fast component was more sensitive to prior heavy exercise than was the associated time constant. Key words: impedance cardiography, exercise transitions, cardiac output, prior exercise

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Effects of prior heavy exercise on phase II pulmonary oxygen uptake kinetics during heavy exercise

Journal of Applied Physiology ◽

10.1152/jappl.2000.89.4.1387 ◽

2000 ◽

Vol 89 (4) ◽

pp. 1387-1396 ◽

Cited By ~ 152

Author(s):

Mark Burnley ◽

Andrew M. Jones ◽

Helen Carter ◽

Jonathan H. Doust

Keyword(s):

Oxygen Uptake ◽

Phase Ii ◽

Slow Component ◽

Exercise Bout ◽

Oxygen Uptake Kinetics ◽

Cycle Ergometer ◽

Moderate Exercise ◽

Heavy Exercise ◽

Mean Response Time ◽

The Mean

We tested the hypothesis that heavy-exercise phase II oxygen uptake (V˙o 2) kinetics could be speeded by prior heavy exercise. Ten subjects performed four protocols involving 6-min exercise bouts on a cycle ergometer separated by 6 min of recovery: 1) moderate followed by moderate exercise; 2) moderate followed by heavy exercise; 3) heavy followed by moderate exercise; and 4) heavy followed by heavy exercise. The V˙o 2 responses were modeled using two (moderate exercise) or three (heavy exercise) independent exponential terms. Neither moderate- nor heavy-intensity exercise had an effect on the V˙o 2 kinetic response to subsequent moderate exercise. Although heavy-intensity exercise significantly reduced the mean response time in the second heavy exercise bout (from 65.2 ± 4.1 to 47.0 ± 3.1 s; P < 0.05), it had no significant effect on either the amplitude or the time constant (from 23.9 ± 1.9 to 25.3 ± 2.9 s) of theV˙o 2 response in phase II. Instead, this “speeding” was due to a significant reduction in the amplitude of the V˙o 2 slow component. These results suggest phase II V˙o 2 kinetics are not speeded by prior heavy exercise.

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Oxygen uptake kinetics during treadmill running in boys and men

Journal of Applied Physiology ◽

10.1152/jappl.2001.90.5.1700 ◽

2001 ◽

Vol 90 (5) ◽

pp. 1700-1706 ◽

Cited By ~ 46

Author(s):

Craig A. Williams ◽

Helen Carter ◽

Andrew M. Jones ◽

Jonathan H. Doust

Keyword(s):

Oxygen Uptake ◽

Time Constant ◽

Slow Component ◽

Oxygen Uptake Kinetics ◽

Primary Response ◽

Treadmill Running ◽

Initial Increase ◽

Moderate Exercise ◽

Heavy Exercise ◽

The Difference

The purpose of this study was to compare the kinetics of the oxygen uptake (V˙o 2) response of boys to men during treadmill running using a three-phase exponential modeling procedure. Eight boys (11–12 yr) and eight men (21–36 yr) completed an incremental treadmill test to determine lactate threshold (LT) and maximum V˙o 2. Subsequently, the subjects exercised for 6 min at two different running speeds corresponding to 80% of V˙o 2 at LT (moderate exercise) and 50% of the difference betweenV˙o 2 at LT and maximumV˙o 2 (heavy exercise). For moderate exercise, the time constant for the primary response was not significantly different between boys [10.2 ± 1.0 (SE) s] and men (14.7 ± 2.8 s). The gain of the primary response was significantly greater in boys than men (239.1 ± 7.5 vs. 167.7 ± 5.4 ml · kg−1 · km−1; P < 0.05). For heavy exercise, theV˙o 2 on-kinetics were significantly faster in boys than men (primary response time constant = 14.9 ± 1.1 vs. 19.0 ± 1.6 s; P < 0.05), and the primary gain was significantly greater in boys than men (209.8 ± 4.3 vs. 167.2 ± 4.6 ml · kg−1 · km−1; P < 0.05). The amplitude of theV˙o 2 slow component was significantly smaller in boys than men (19 ± 19 vs. 289 ± 40 ml/min; P < 0.05). The V˙o 2responses at the onset of moderate and heavy treadmill exercise are different between boys and men, with a tendency for boys to have faster on-kinetics and a greater initial increase inV˙o 2 for a given increase in running speed.

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Effect of creatine supplementation on oxygen uptake kinetics during submaximal cycle exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.01065.2001 ◽

2002 ◽

Vol 92 (6) ◽

pp. 2571-2577 ◽

Cited By ~ 41

Author(s):

Andrew M. Jones ◽

Helen Carter ◽

Jamie S. M. Pringle ◽

Iain T. Campbell

Keyword(s):

Oxygen Uptake ◽

Ventilatory Threshold ◽

Vastus Lateralis ◽

Creatine Supplementation ◽

Oxygen Uptake Kinetics ◽

Primary Component ◽

Heavy Exercise ◽

Cycle Exercise ◽

Oral Consumption ◽

Type Ii Fibers

The purpose of this study was to test the effect of oral creatine (Cr) supplementation on pulmonary oxygen uptake (V˙o 2) kinetics during moderate [below ventilatory threshold (VT)] and heavy (above VT) submaximal cycle exercise. Nine subjects (7 men; means ± SD: age 28 ± 3 yr, body mass 73.2 ± 5.6 kg, maximalV˙o 2 46.4 ± 8.0 ml · kg−1 · min−1) volunteered to participate in this study. Subjects performed transitions of 6-min duration from unloaded cycling to moderate (80% VT; 8–12 repeats) and heavy exercise (50% change; i.e., halfway between VT and maximal V˙o 2; 4–6 repeats), both in the control condition and after Cr loading, in a crossover design. The Cr loading regimen involved oral consumption of 20 g/day of Cr monohydrate for 5 days, followed by a maintenance dose of 5 g/day thereafter. V˙o 2 was measured breath by breath and modeled by using two (moderate) or three (heavy) exponential terms. For moderate exercise, there were no differences in the parameters of the V˙o 2 kinetic response between control and Cr-loaded conditions. For heavy exercise, the time-based parameters of the V˙o 2response were unchanged, but the amplitude of the primary component was significantly reduced with Cr loading (means ± SE: control 2.00 ± 0.12 l/min; Cr loaded 1.92 ± 0.10 l/min; P < 0.05) as was the end-exerciseV˙o 2 (control 2.19 ± 0.13 l/min; Cr loaded 2.12 ± 0.14 l/min; P < 0.05). The magnitude of the reduction in submaximalV˙o 2 with Cr loading was significantly correlated with the percentage of type II fibers in the vastus lateralis ( r = 0.87; P < 0.01; n = 7), indicating that the effect might be related to changes in motor unit recruitment patterns or the volume of muscle activated.

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A Single Bout of Constant-Load Exercise Test for Estimating the Time Constant of Oxygen Uptake Kinetics in Individuals With Stroke

Annals of Rehabilitation Medicine ◽

10.5535/arm.21087 ◽

2021 ◽

Vol 45 (4) ◽

pp. 304-313

Author(s):

Kazuaki Oyake ◽

Yasuto Baba ◽

Yuki Suda ◽

Jun Murayama ◽

Ayumi Mochida ◽

...

Keyword(s):

Oxygen Uptake ◽

Time Constant ◽

Ventilatory Threshold ◽

Exercise Bout ◽

Relative Difference ◽

Constant Load ◽

Oxygen Uptake Kinetics ◽

Uptake Kinetics ◽

Single Bout ◽

The Relationship

Objective To examine the relationship between the time constant of oxygen uptake kinetics during the onset of exercise (τVO2) estimated from a single exercise bout and that obtained from three averaged exercise bouts in individuals with stroke.Methods Twenty participants with stroke performed three bouts of a constant-load pedaling exercise at approximately 80% of the workload corresponding to the ventilatory threshold to estimate τVO2. The VO2 data from the first trial of three bouts were used to estimate τVO2 for a single bout. Additionally, data collected from three bouts were ensemble-averaged to obtain τVO2 for three averaged bouts as the criterion.Results There was a very high correlation between τVO2 for a single bout (34.8±14.0 seconds) and τVO2 for three averaged bouts (38.5±13.4 seconds) (r=0.926, p<0.001). However, τVO2 for a single bout was smaller than that for three averaged bouts (p=0.006).Conclusion τVO2 for a single bout could reflect the relative difference in τVO2 for three averaged bouts among individuals with stroke. However, it should be noted that τVO2 for a single bout may be underestimated compared to τVO2 for three averaged bouts.

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Effect of muscle mass on V˙o 2kinetics at the onset of work

Journal of Applied Physiology ◽

10.1152/jappl.2001.90.2.461 ◽

2001 ◽

Vol 90 (2) ◽

pp. 461-468 ◽

Cited By ~ 19

Author(s):

Shunsaku Koga ◽

Thomas J. Barstow ◽

Tomoyuki Shiojiri ◽

Tetsuo Takaishi ◽

Yoshiyuki Fukuba ◽

...

Keyword(s):

Muscle Mass ◽

Ventilatory Threshold ◽

Slow Component ◽

Cycle Ergometer ◽

Muscle Recruitment ◽

Heavy Exercise ◽

Mean Response Time ◽

Heavy Work ◽

Exercise Transitions ◽

Recruitment Patterns

The dependence of O2 uptake (V˙o 2) kinetics on the muscle mass recruited under conditions when fiber and muscle recruitment patterns are similar following the onset of exercise has not been determined. We developed a motorized cycle ergometer that facilitated one-leg (1L) cycling in which the electromyographic (EMG) profile of the active muscles was not discernibly altered from that during two-leg (2L) cycling. Six subjects performed 1L and 2L exercise transitions from unloaded cycling to moderate [<ventilatory threshold (VT)] and heavy (>VT) exercise. The 1L condition yielded kinetics that was unchanged from the 2L condition [the phase 2 time constants (τ1, in s) for <VT were as follows: 1L = 16.8±8.4 (SD), 2L = 18.4 ± 8.1, P > 0.05; for >VT: 1L = 26.8 ± 12.0; 2L = 27.8 ± 16.1, P > 0.05]. The overall V˙o 2 kinetics (mean response time) was not significantly different for the two exercise conditions. However, the gain of the fast component (the amplitude/work rate) during the 1L exercise was significantly higher than that for the 2L exercise for both moderate and heavy work rates. The slow-component responses evident for heavy exercise were temporally and quantitatively unaffected by the 1L condition. These data demonstrate that, when leg muscle recruitment patterns are unchanged as assessed by EMG analysis, on-transient V˙o 2 kinetics for both moderate and heavy exercise are not dependent on the muscle mass recruited.

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Kinetics of oxygen uptake during supine and upright heavy exercise

Journal of Applied Physiology ◽

10.1152/jappl.1999.87.1.253 ◽

1999 ◽

Vol 87 (1) ◽

pp. 253-260 ◽

Cited By ~ 82

Author(s):

Shunsaku Koga ◽

Tomoyuki Shiojiri ◽

Manabu Shibasaki ◽

Narihiko Kondo ◽

Yoshiyuki Fukuba ◽

...

Keyword(s):

Heart Rate ◽

Oxygen Uptake ◽

Supine Position ◽

Slow Component ◽

Fast Component ◽

Heavy Exercise ◽

The Difference ◽

Early Rise ◽

Kinetics Of ◽

State Increase

It is presently unclear how the fast and slow components of pulmonary oxygen uptake (V˙o 2) kinetics would be altered by body posture during heavy exercise [i.e., above the lactate threshold (LT)]. Nine subjects performed transitions from unloaded cycling to work rates representing moderate (below the estimated LT) and heavy exercise (V˙o 2 equal to 50% of the difference between LT and peakV˙o 2) under conditions of upright and supine positions. During moderate exercise, the steady-state increase in V˙o 2was similar in the two positions, butV˙o 2 kinetics were slower in the supine position. During heavy exercise, the rate of adjustment ofV˙o 2 to the 6-min value was also slower in the supine position but was characterized by a significant reduction in the amplitude of the fast component ofV˙o 2, without a significant slowing of the phase 2 time constant. However, the amplitude of the slow component was significantly increased, such that the end-exerciseV˙o 2 was the same in the two positions. The changes inV˙o 2 kinetics for the supine vs. upright position were paralleled by a blunted response of heart rate at 2 min into exercise during supine compared with upright heavy exercise. Thus the supine position was associated with not only a greater amplitude of the slow component forV˙o 2 but also, concomitantly, with a reduced amplitude of the fast component; this latter effect may be due, at least in part, to an attenuated early rise in heart rate in the supine position.

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Effect of increased muscle temperature on oxygen uptake kinetics during exercise

Journal of Applied Physiology ◽

10.1152/jappl.1997.83.4.1333 ◽

1997 ◽

Vol 83 (4) ◽

pp. 1333-1338 ◽

Cited By ~ 71

Author(s):

Shunsaku Koga ◽

Tomoyuki Shiojiri ◽

Narihiko Kondo ◽

Thomas J. Barstow

Keyword(s):

Oxygen Uptake ◽

Slow Component ◽

Oxygen Uptake Kinetics ◽

Work Rate ◽

Uptake Kinetics ◽

Hot Water ◽

Muscle Temperature ◽

Appreciable Effect ◽

Heavy Exercise ◽

The Difference

Koga, Shunsaku, Tomoyuki Shiojiri, Narihiko Kondo, and Thomas J. Barstow. Effect of increased muscle temperature on oxygen uptake kinetics during exercise. J. Appl. Physiol. 83(4): 1333–1338, 1997.—To test whether increased muscle temperature (Tm) would improve O2 uptake (V˙o 2) kinetics, seven men performed transitions from rest to a moderate work rate [below the estimated lactate threshold (LTest)] and a heavy work rate (V˙o 2 = 50% of the difference between LTest and peakV˙o 2) under conditions of normal Tm (N) and increased Tm (H), produced by wearing hot water-perfused pants before exercise. Quadriceps Tm was significantly higher in H, but rectal temperature was similar for the two conditions. There were no significant differences in the amplitudes of the fast component ofV˙o 2 or in the time constants of the on and off transients for moderate and heavy exercise between the two conditions. The increment inV˙o 2 between the 3rd and 6th min of heavy exercise was slightly but significantly smaller for H than for N. These data suggest that elevated Tm before exercise onset, which would have been expected to increase O2 delivery and off-loading to the muscle, had no appreciable effect on the fast exponential component ofV˙o 2 kinetics (invariant time constant). These data further suggest that elevated Tm does not contribute to the slow component of V˙o 2 during heavy exercise.

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Dynamic Responses of Oxygen Uptake at the Onset and End of Moderate and Heavy Exercise in Trained Subjects

Canadian Journal of Applied Physiology ◽

10.1139/h04-003 ◽

2004 ◽

Vol 29 (1) ◽

pp. 32-44 ◽

Cited By ~ 8

Author(s):

Christophe Cleuziou ◽

Stéphane Perrey ◽

Fabio Borrani ◽

Anne Marie Lecoq ◽

Robin Candau ◽

...

Keyword(s):

Oxygen Uptake ◽

Ventilatory Threshold ◽

Slow Component ◽

Exponential Model ◽

Dynamic Responses ◽

Parameter Estimates ◽

Heavy Exercise ◽

Cycling Exercise ◽

Trained Subjects ◽

Key Words Oxygen Uptake

Inconsistencies about dynamic asymmetry between the on- and off-transient responses in [Formula: see text] are found in the literature. Therefore the purpose of this study was to examine [Formula: see text]on-and off-transients during moderate- and heavy-intensity cycling exercise in trained subjects. Ten men underwent an initial incremental test for the estimation of ventilatory threshold (VT) and, on different days, two bouts of square-wave exercise at moderate (< VT) and heavy (> VT) intensities. [Formula: see text] kinetics in exercise and recovery were better described by a single exponential model (< VT), or by a double exponential with two time delays (> VT). For moderate exercise, we found a symmetry of [Formula: see text] kinetics between the on- and off-transients (i.e., fundamental component), consistent with a system manifesting linear control dynamics. For heavy exercise, a slow component superimposed on the fundamental phase was expressed in both the exercise and recovery, with similar parameter estimates. But the on-transient values of the time constant were appreciably faster than the associated off-transient, and independent of the work rate imposed (< VT and > VT). Our results do not support a dynamically linear system model of [Formula: see text] during cycling exercise in the heavy-intensity domain. Key words: oxygen uptake kinetics, on- and off-transients, slow component

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Hemodynamic and metabolic responses to self-paced and ramp-graded exercise testing protocols

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2017-0608 ◽

2018 ◽

Vol 43 (6) ◽

pp. 609-616 ◽

Cited By ~ 3

Author(s):

Nicholas M. Beltz ◽

Fabiano T. Amorim ◽

Ann L. Gibson ◽

Jeffrey M. Janot ◽

Len Kravitz ◽

...

Keyword(s):

Cardiac Output ◽

Oxygen Consumption ◽

Oxygen Uptake ◽

Exercise Testing ◽

Ventilatory Threshold ◽

Maximal Oxygen Consumption ◽

Oxygen Uptake Kinetics ◽

Metabolic Responses ◽

Graded Exercise Testing ◽

Graded Exercise

Recent examinations have shown lower maximal oxygen consumption during traditional ramp (RAMP) compared with self-paced (SPV) graded exercise testing (GXT) attributed to differences in cardiac output. The current study examined the differences in hemodynamic and metabolic responses between RAMP and SPV during treadmill exercise. Sixteen recreationally trained men (aged23.7 ± 3.0 years) completed 2 separate treadmill GXT protocols. SPV consisted of five 2-min stages (10 min total) of increasing speed clamped by the Borg RPE6-20 scale. RAMP increased speed by 0.16 km/h every 15 s until volitional exhaustion. All testing was performed at 3% incline. Oxygen consumption was measured via indirect calorimetry; hemodynamic function was measured via thoracic impedance and blood lactate (BLa−) was measured via portable lactate analyzer. Differences between SPV and RAMP protocols were analyzed as group means by using paired-samples t tests (R Core Team 2017). Maximal values for SPV and RAMP were similar (p > 0.05) for oxygen uptake (47.1 ± 3.4 vs. 47.4 ± 3.4 mL·kg−1·min−1), heart rate (198 ± 5 vs. 200 ± 6 beats·min−1), ventilation (158.8 ± 20.7 vs. 159.3 ± 19.0 L·min−1), cardiac output (26.9 ± 5.5 vs. 27.9 ± 4.2 L·min−1), stroke volume (SV) (145.9 ± 29.2 vs. 149.8 ± 25.3 mL·beat−1), arteriovenous oxygen difference (18.5 ± 3.1 vs. 19.7 ± 3.1 mL·dL−1), ventilatory threshold (VT) (78.2 ± 7.2 vs. 79.0% ± 7.6%), and peak BLa− (11.7 ± 2.3 vs. 11.5 ± 2.4 mmol·L−1), respectively. In conclusion, SPV elicits similar maximal hemodynamic responses in comparison to RAMP; however, SV kinetics exhibited unique characteristics based on protocol. These results support SPV as a feasible GXT protocol to identify useful fitness parameters (maximal oxygen uptake, oxygen uptake kinetics, and VT).

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