Relationship between hyperventilation and excessive CO2 output during recovery from repeated cycling sprints

The purpose of the present study was to examine whether excessive CO2 output (VCO2excess) is dominantly attributable to hyperventilation during the period of recovery from repeated cycling sprints. A series of four 10-sec cycling sprints with 30-sec passive recovery periods was performed two times. The first series and second series of cycle sprints (SCS) were followed by 360-sec passive recovery periods (first recovery and second recovery). Increases in blood lactate (DeltaLa) were 11.17+/-2.57 mM from rest to 5.5 min during first recovery and 2.07+/-1.23 mM from the start of the second SCS to 5.5 min during second recovery. CO2 output (VCO2) was significantly higher than O2 uptake (VO2) during both recovery periods. This difference was defined as VCO2excess. VCO2excess was significantly higher during first recovery than during second recovery. VCO2excess was added from rest to the end of first recovery and from the start of the second SCS to the end of second recovery (CO2excess). DeltaLa was significantly related to CO2excess (r=0.845). However, ventilation during first recovery was the same as that during second recovery. End-tidal CO2 pressure (PETCO2) significantly decreased from the resting level during the recovery periods, indicating hyperventilation. PETCO2 during first recovery was significantly higher than that during second recovery. It is concluded that VCO2excess is not simply determined by ventilation during recovery from repeated cycle sprints.

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Effects of naloxone on maximal stress testing in females

Journal of Applied Physiology ◽

10.1152/jappl.1984.56.2.436 ◽

1984 ◽

Vol 56 (2) ◽

pp. 436-440 ◽

Cited By ~ 7

Author(s):

R. G. McMurray ◽

D. S. Sheps ◽

D. M. Guinan

Keyword(s):

Perceived Exertion ◽

Exercise Duration ◽

Time To Exhaustion ◽

O2 Uptake ◽

Ratings Of Perceived Exertion ◽

Double Blind ◽

Co2 Partial Pressure ◽

End Tidal ◽

End Tidal Co2 ◽

Naloxone Treatment

To examine the effect of naloxone (an opiate antagonist) on exercise performance, six normal females (20–28 yr) walked on a treadmill (93.8 m/min) with the grade increasing 2.5% every 4 min until exhaustion. Each subject completed three trials: naloxone infusion (0.4 mg/ml saline), saline infusion (1 ml), and an infusion control. The order of trials was randomized and double blind. Each subject responded similarly at each submaximal stage for all three trials. The results during maximal exertion were different. Time to exhaustion was similar for all conditions, averaging 32.6 +/- 3.0 min with a maximal O2 uptake of 38.8 +/- 2.8 ml X kg-1 X min-1 and a lactate of 9.1 +/- 1.1 mmol/l. Maximal ventilation (BTPS) was 7.9 l/min less during the naloxone treatment when compared with either control or placebo trials (P less than 0.05). This difference was attributed to a 4-breath/min reduction in respiratory frequency (P less than 0.05). End-tidal CO2 partial pressure was approximately 4 Torr higher at maximum after naloxone injection. Maximal heart rates averaged 190.8 +/- 3.8 beats/min for both control and placebo trials. This was significantly greater (P less than 0.05) than the 185 +/- 2.4 beats/min recorded for the naloxone trials. Ratings of perceived exertion were 17.0 +/- 1.3 units at maximum, similar for all three trials. Despite these statistically significant cardiorespiratory differences, naloxone produced no effect on maximum O2 uptake or exercise duration.

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The physiological mechanism behind the talk test

Kinesiology ◽

10.26582/k.49.1.15 ◽

2017 ◽

Vol 49 (1) ◽

pp. 3-8 ◽

Cited By ~ 1

Author(s):

Noortje Creemers ◽

Jos J. de Koning

Keyword(s):

Minute Ventilation ◽

Physiological Mechanism ◽

Cycle Ergometer ◽

Potential Mechanism ◽

Breathing Frequency ◽

Co2 Output ◽

Ventilatory Drive ◽

Aged Subjects ◽

End Tidal ◽

End Tidal Co2

The Talk Test (TT) is a very simple marker of exercise intensity, which has been shown to be a useful surrogate of the ventilatory (VT) and respiratory compensation (RCT) thresholds. The purpose of this study was to evaluate a potential mechanism behind the TT. Healthy, college-aged subjects (n=20) performed a maximal and two sub-maximal cycle ergometer tests. The two submaximal tests were performed: with the Talk Test (EXP) and without speaking (the control trial – CON). Oxygen uptake (VO2), CO2 output (VCO2), minute ventilation (VE), breathing frequency (BF), end-tidal CO2 pressure (PETCO2) and TT times were recorded. VO2, VCO2 and VE were reduced during the TT and increased immediately after it. BF was reduced during the TT. PETCO2 values (a surrogate of PaCO2) were highest during the TT and lowest before the TT. The time to complete the TT increased across progressive stages. This study supports the hypothesis that talking causes CO2 retention, which may cause ventilatory drive to increase. Since the ventilatory drive is already high above the VT, the apparent CO2 retention associated with speech may cause talking to become uncomfortable

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Determinants of gas exchange kinetics during exercise in the dog

Journal of Applied Physiology ◽

10.1152/jappl.1979.46.6.1054 ◽

1979 ◽

Vol 46 (6) ◽

pp. 1054-1060 ◽

Cited By ~ 22

Author(s):

R. Casaburi ◽

M. L. Weissman ◽

D. J. Huntsman ◽

B. J. Whipp ◽

K. Wasserman

Keyword(s):

Co2 Exchange ◽

Appreciable Effect ◽

O2 Uptake ◽

Arterial Pco2 ◽

Co2 Output ◽

Exercise Onset ◽

Anesthetized Dogs ◽

Time Courses ◽

End Tidal ◽

Gas Exchange Kinetics

Following exercise onset, CO2 output (VCO2) and O2 uptake (VO2) increase exponentially, but with appreciably different time constants. To determine the sensitivity of the time courses of these variables to altered ventilatory kinetics, rhythmic exercise was induced abruptly in anesthetized dogs by bilateral stimulation of the peripheral ends of the cut sciatic and femoral nerves. This increased the metabolic rate by 83 +/- 25 (SD) %. The dogs were ventilated with a constant-volume pump, the frequency of which was changed exponentially from the start of the exercise up to the ventilation that returned arterial CO2 and O2 pressure (PCO2 and PO2) in the steady state to resting levels. The time constant (tau) of the increase in ventilation (VE) was varied among trials. VCO2, VO2, end-tidal PCO2 and PO2, and arterial PCO2 were measured breath by breath. tauVO2 was constant at approximately 18 s regardless of alterations in tauVE. In contrast, tauVCO2 was strongly dependent on tauVE, apparently due to the larger body stores for CO2; the transitions were isocapnic when tau VE was approximately 40 s. We conclude that ventilatory dynamics can markedly influence the dynamics of CO2 exchange during exercise, but has no appreciable effect on O2 uptake dynamics.

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Blood lactate disappearance at various intensities of recovery exercise

Journal of Applied Physiology ◽

10.1152/jappl.1984.57.5.1462 ◽

1984 ◽

Vol 57 (5) ◽

pp. 1462-1465 ◽

Cited By ~ 66

Author(s):

S. Dodd ◽

S. K. Powers ◽

T. Callender ◽

E. Brooks

Keyword(s):

Blood Lactate ◽

Maximal Exercise ◽

Exercise Recovery ◽

Intense Exercise ◽

O2 Uptake ◽

Vo2 Max ◽

Passive Recovery ◽

Significant Difference ◽

Recovery Exercise ◽

Treatment Order

Numerous studies have reported that following intense exercise the rate of blood lactate (La) disappearance is greater during continuous aerobic work than during passive recovery. Recent work indicates that a combination of high- and low-intensity work may be optimal in reducing blood La. We tested this hypothesis by measuring the changes in blood La levels following maximal exercise during four different recovery patterns. Immediately following 50 S of maximal work, subjects (n = 7) performed one of the following recovery treatments for 40 min: 1) passive recovery (PR); 2) cycling at 35% maximal O2 uptake (VO2 max) (35% R); 3) cycling at 65% VO2 max (65% R); 4) cycling at 65% for 7 min followed by cycling at 35% for 33 min (CR). The treatment order was counterbalanced with each subject performing all treatments. Serial blood samples were obtained throughout recovery treatments and analyzed for La. The rate of blood La disappearance was significantly greater (P less than 0.05) in both the 35% R and CR when compared with either the 65% R or PR. No significant difference (P greater than 0.05) existed in the rate of blood La disappearance between the 35% R and CR. These data do not support the hypothesis that exercise recovery at a combination of intensities is superior to a recovery involving continuous submaximal exercise in lowering blood La following maximal work.

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Cardiorespiratory Functioning in Youth with Persistent Post-Concussion Symptoms: A Pilot Study

Journal of Clinical Medicine ◽

10.3390/jcm10040561 ◽

2021 ◽

Vol 10 (4) ◽

pp. 561

Author(s):

Aliyah Snyder ◽

Christopher Sheridan ◽

Alexandra Tanner ◽

Kevin Bickart ◽

Molly Sullan ◽

...

Keyword(s):

Processing Speed ◽

Mean Value ◽

Exhaled Breath ◽

Post Injury ◽

The Past ◽

Neurobehavioral Outcomes ◽

End Tidal ◽

Relationship Of ◽

The Relationship ◽

End Tidal Co2

Dysregulation of the autonomic nervous system (ANS) may play an important role in the development and maintenance of persistent post-concussive symptoms (PPCS). Post-injury breathing dysfunction, which is influenced by the ANS, has not been well-studied in youth. This study evaluated cardiorespiratory functioning at baseline in youth patients with PPCS and examined the relationship of cardiorespiratory variables with neurobehavioral outcomes. Participants were between the ages of 13–25 in two groups: (1) Patients with PPCS (concussion within the past 2–16 months; n = 13) and (2) non-injured controls (n = 12). Capnometry was used to obtain end-tidal CO2 (EtCO2), oxygen saturation (SaO2), respiration rate (RR), and pulse rate (PR) at seated rest. PPCS participants exhibited a reduced mean value of EtCO2 in exhaled breath (M = 36.3 mmHg, SD = 2.86 mmHg) and an altered inter-correlation between EtCO2 and RR compared to controls. Neurobehavioral outcomes including depression, severity of self-reported concussion symptoms, cognitive catastrophizing, and psychomotor processing speed were correlated with cardiorespiratory variables when the groups were combined. Overall, results from this study suggest that breathing dynamics may be altered in youth with PPCS and that cardiorespiratory outcomes could be related to a dimension of neurobehavioral outcomes associated with poorer recovery from concussion.

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