Effect of Altered Body CO<sub>2</sub> Stores on Pulmonary Gas Exchange Dynamics During Incremental Exercise in Humans

Özçelik, Oğuz; Ward, Susan A.; Whipp, Brian J.

doi:10.1111/j.1469-445x.1999.01868.x

Cited by 43 publications

(27 citation statements)

References 27 publications

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“…One subject was removed from data analyses due to large breath-to-breath variability in breathing pattern data recorded during incremental exercise. Another four participants were excluded from analyses due to a high-risk of pseudo-G EX 1 detection-marked by an abnormally high ([1.0) respiratory exchange ratio during the initial stages of the incremental protocol (Cannon et al 2009;Ozcelik et al 1999;Whipp 2007). The € f R 1 and € f R 2 were successfully identified in all remaining subjects (n = 23) using the polynomial spline smoothing technique.…”

Section: Resultsmentioning

confidence: 99%

Evidence of break-points in breathing pattern at the gas-exchange thresholds during incremental cycling in young, healthy subjects

et al. 2011

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The present study investigated whether 'break-points' in breathing pattern correspond to the first ([Formula: see text]) and second gas-exchange thresholds ([Formula: see text]) during incremental cycling. We used polynomial spline smoothing to detect accelerations and decelerations in pulmonary gas-exchange data, which provided an objective means of 'break-point' detection without assumption of the number and shape of said 'break-points'. Twenty-eight recreational cyclists completed the study, with five individuals excluded from analyses due to low signal-to-noise ratios and/or high risk of 'pseudo-threshold' detection. In the remaining participants (n = 23), two separate and distinct accelerations in respiratory frequency (f (R)) during incremental work were observed, both of which demonstrated trivial biases and reasonably small ±95% limits of agreement (LOA) for the [Formula: see text] (0.2 ± 3.0 ml O(2) kg(-1) min(-1)) and [Formula: see text] (0.0 ± 2.4 ml O(2) kg(-1) min(-1)), respectively. A plateau in tidal volume (V (T)) data near the [Formula: see text] was identified in only 14 individuals, and yielded the most unsatisfactory mean bias ±LOA of all comparisons made (-0.4 ± 5.3 ml O(2) kg(-1) min(-1)). Conversely, 18 individuals displayed V (T)-plateau in close proximity to the [Formula: see text] evidenced by a mean bias ± LOA of 0.1 ± 3.1 ml O(2) kg(-1) min(-1). Our findings suggest that both accelerations in f (R) correspond to the gas-exchange thresholds, and a plateau (or decline) in V (T) at the [Formula: see text] is a common (but not universal) feature of the breathing pattern response to incremental cycling.

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Section: Resultsmentioning

confidence: 99%

Evidence of break-points in breathing pattern at the gas-exchange thresholds during incremental cycling in young, healthy subjects

et al. 2011

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“…The ventilatory threshold was identified as the first breakpoint in the _ V CO 2 versus _ V O 2 relationship (Beaver et al 1986). The criteria proposed by Ozcelik et al (1999) as indicative that a genuine rather than a pseudo threshold has been identified were met in all subjects.…”

Section: Discussionmentioning

confidence: 99%

The V?O2 response for an exhaustive treadmill run at 800-m pace: a breath-by-breath analysis

Draper

Wood

2004

Eur J Appl Physiol

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Recent research in which data were averaged over 10 or 30 s suggests that the VO(2) response of aerobically fit individuals plateaus below VO(2 max) in an exhaustive square-wave run lasting approximately 2 min. To investigate this phenomenon we examined the breath-by-breath VO(2) response of trained runners to an exhaustive treadmill run at 800 m pace. Eight male competitive runners completed two treadmill tests on separate days: a ramp test to exhaustion and an exhaustive square-wave run at 800-m pace. For the ramp test, the breath-by-breath data were smoothed with a 15-s moving average and the highest of the smoothed values was taken as VO(2 peak) [mean (SD): 68.9 (5.6) ml kg(-1) min(-1)]. For the square-wave, the breath-by-breath data were interpolated to give one value per second and modelled using a monoexponential function. Following a delay of 11.2 (1.5) s, VO(2) increased quickly [phase-2 time constant of 10.7 (2.7) s] towards an asymptote that represented just 85 (6)% of VO(2 peak) from the ramp test. Expressed in ml kg(-1) min(-1), this asymptote was independent of VO(2 peak) (r=0.04, P=0.94). However, as a percentage of VO(2 peak) it was negatively correlated with VO(2 peak) itself (r=-0.96, P<0.001). It is concluded that in an exhaustive square-wave treadmill run lasting approximately 2 min the VO(2) of aerobically fit runners increases quickly to plateau at a level that is lower than, but independent of, VO(2max).

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“…Ventilation and pulmonary gas exchange were measured breath-by-breath using an Oxycon a system (Jaeger, Hochberg, Germany). The lactic acidosis threshold (h L ) was estimated using the V-Slope (Beaver et al 1986) method and related indices (Ozcelik et al 1999). Patients performed the constant WR exercise tests in a randomized sequence (on different days) at an intensity of 80% of that of h L , and at two levels above the pretraining work-rate at the lactic acidosis threshold (WRh L ).…”

Section: Methodsmentioning

confidence: 99%

Training improves muscle oxidative capacity and oxygenation recovery kinetics in patients with chronic obstructive pulmonary disease

et al. 2003

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We studied 21 patients with chronic obstructive pulmonary disease aged [mean (SD)] 63 (10) years, with a mean forced expiratory volume in 1 s of 40 (6)% and a peak oxygen uptake of 67 (11)% of predicted values. Patients trained for 6 weeks on a cycle ergometer at high work-rates (WR). Near-infrared spectroscopy was used to obtain the time-constant of the deoxygenation recovery signal (tauHbO(2)) during three constant WR exercise tests, one below and two above the lactic acidosis threshold (theta(L)). Glycolytic and oxidative enzymes and lactate concentrations were assessed in muscle biopsies. The tauHbO(2) decreased significantly in all three constant WR tests: -18 (24)s, -20 (23) s and -13 (22) s, respectively. Endurance time increased in the higher WR tests, by 5.7 (4.8) min and 3.6 (2.7) min, respectively. The activity of citrate-synthase (CS) and creatine-kinase changed significantly from 20 (10) to 30 (13) micro mol x min(-1) x g(-1)and from 3.825 (950) to 3.402 (526) micro mol x min(-1) x g(-1), respectively. Training also improved significantly the mean response time of the on-transient of oxygen uptake (tau'VO(2)) of the below-theta(L) test. We found significant correlations between changes in CS and changes in tauHbO(2), tau'VO(2) and endurance time. We conclude that leg training accelerates the speed of re-oxygenation of the vastus lateralis muscle after exercise. This improvement is correlated to changes in the oxidative enzymes.

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Effect of Altered Body CO₂ Stores on Pulmonary Gas Exchange Dynamics During Incremental Exercise in Humans

Abstract: summaryThe lactate threshold is a widely used and, at times, controversial construct in exercise physiology and pathophysiology.

Cited by 43 publications

References 27 publications

Evidence of break-points in breathing pattern at the gas-exchange thresholds during incremental cycling in young, healthy subjects

Evidence of break-points in breathing pattern at the gas-exchange thresholds during incremental cycling in young, healthy subjects

The V?O2 response for an exhaustive treadmill run at 800-m pace: a breath-by-breath analysis

Training improves muscle oxidative capacity and oxygenation recovery kinetics in patients with chronic obstructive pulmonary disease

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Effect of Altered Body CO2 Stores on Pulmonary Gas Exchange Dynamics During Incremental Exercise in Humans

Abstract: summaryThe lactate threshold is a widely used and, at times, controversial construct in exercise physiology and pathophysiology.

Cited by 43 publications

References 27 publications

Evidence of break-points in breathing pattern at the gas-exchange thresholds during incremental cycling in young, healthy subjects

Evidence of break-points in breathing pattern at the gas-exchange thresholds during incremental cycling in young, healthy subjects

The V?O2 response for an exhaustive treadmill run at 800-m pace: a breath-by-breath analysis

Training improves muscle oxidative capacity and oxygenation recovery kinetics in patients with chronic obstructive pulmonary disease

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Effect of Altered Body CO₂ Stores on Pulmonary Gas Exchange Dynamics During Incremental Exercise in Humans