Response to ventilatory obstruction during steady-state exercise

1960 ◽  
Vol 15 (4) ◽  
pp. 579-582 ◽  
Author(s):  
Burton S. Tabakin ◽  
John S. Hanson
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Oxygen Uptake ◽  
Treadmill Exercise ◽  
Minute Volume ◽  
Normal Male ◽  
Carbon Dioxide Elimination ◽  
Physiological Mechanisms ◽  
Total Period ◽  
Male Subjects

Five normal male subjects, 27–37 years of age, were studied during steady-state treadmill exercise to observe the effects of varying expiratory airway obstruction on minute volume, oxygen consumption and carbon dioxide elimination. A 5-mm-diameter resistance produced significant depressions in minute volume for the duration of the obstructed period. Carbon dioxide elimination showed significant reductions during the first 6 minutes of breathing against resistance. Oxygen uptake, however, was reduced significantly only during the 1st minute of obstructed breathing, but the reduction was great enough so that, despite subsequent rises in oxygen uptake, an ‘oxygen debt’ had already been incurred for the total period of obstruction. Following removal of the resistance, all these values rebounded to levels above those of the original steady state. The physiological mechanisms possibly effecting the response to obstruction are discussed. Submitted on February 24, 1959

Hemodynamic response of normal men to graded treadmill exercise

1964 ◽  
Vol 19 (3) ◽  
pp. 457-464 ◽  
Author(s):  
Burton S. Tabakin ◽  
John S. Hanson ◽  
Thornton W. Merriam ◽  
Edgar J. Caldwell
Keyword(s):  
Carbon Dioxide ◽  
Heart Rate ◽  
Cardiac Output ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Treadmill Exercise ◽  
Minute Volume ◽  
Peripheral Vascular ◽  
Carbon Dioxide Elimination ◽  
Oxygen Utilization

The physiologic variables defining the circulatory and respiratory state in normal man have been measured in recumbency, standing at rest and during progressively severe grades of exercise approaching near-maximal levels. Indicator-dilution technique was used for determination of cardiac output with simultaneous radio-electrocardiographic recordings of heart rate. Direct intra-arterial pressure measurements were utilized for calculation of peripheral vascular resistance. Minute volume of ventilation, oxygen utilization, and carbon dioxide elimination were obtained from analysis of expired air collected at the time of each cardiac output determination. A peak mean workload of 1,501 kg-m/min was realized during the treadmill exercise. Increases in cardiac output over the range of exercise employed correlated well with indices of workload such as heart rate, oxygen utilization, and minute volume of ventilation. There was no correlation of stroke volume with these indices. It is concluded from examination of individual stroke-volume responses that a progressive increase in stroke volume is not a necessary or constant phenomenon in adapting to increasing workload. cardiac output in treadmill exercise; dye-dilution cardiac output determinations; arterial pressure during upright exercise; stroke-volume response to graded treadmill exercise; exercise response of cardiac output and stroke volume; peripheral vascular resistance response to position and exercise; treadmill exercise—effects on cardiac output, stroke volume, and oxygen uptake; minute ventilation, cardiac output, and stroke volume during exercise; carbon dioxide elimination during treadmill exercise; heart rate and cardiac output during treadmill exercise; exercise; physiology Submitted on July 12, 1963

Breathing in brief exercise

1960 ◽  
Vol 15 (4) ◽  
pp. 583-588 ◽  
Author(s):  
F. N. Craig ◽  
E. G. Cummings
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Uptake ◽  
Respiratory Exchange Ratio ◽  
Metabolic Cost ◽  
Carbon Dioxide Tension ◽  
Minute Volume ◽  
Carbon Dioxide Output ◽  
Respiratory Minute Volume ◽  
Before And After

Two men ran for 20 or 60 seconds while inhaling air, oxygen or 4% carbon dioxide. Inspired respiratory minute volume was determined for each breath. Ventilation increased suddenly in the first breath with minimal changes in end-expiratory carbon dioxide tension and respiratory exchange ratio to a rate that remained constant for 20 seconds before increasing further. The rate of carbon dioxide output was uniform during the first 20 seconds. A 12% grade did not increase ventilation or oxygen uptake during runs of 20 seconds, but in the first minute of recovery, ventilation was 64% greater than after level runs. Inhalation of oxygen inhibited ventilation by 24% in the 20-second periods before and after the end of a 60-second run. Inhalation of carbon dioxide begun at rest produced increments in ventilation and end-expiratory carbon dioxide tension that varied little during running and recovery. In the 20-second runs ventilation varied with speed but appeared independent of ultimate metabolic cost. Submitted on January 21, 1960

Inhibition of carbonic anhydrase: its effect on carbon dioxide elimination by the lungs

1959 ◽  
Vol 14 (1) ◽  
pp. 109-115 ◽  
Author(s):  
John C. Mithoefer
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Carbonic Anhydrase ◽  
Normal Animal ◽  
Carbon Dioxide Elimination ◽  
Carbonic Anhydrase Inhibition ◽  
Experimental Approaches

The effect of carbonic anhydrase inhibition on carbon dioxide elimination by the lungs has been studied in dogs by the following four experimental approaches: 1) the alveolar pathway (PaOO2 and PaCOCO2) was measured during the hyperventilation which follows carbonic anhydrase inhibition and compared to the normal pathway at the same hyperventilation. 2) The alveolar gas tensions were measured following carbonic anhydrase inhibition when the ventilation was held constant. 3) The changes in PaCOCO2 were measured when the ventilation was suddenly, artificially changed to a new level in the presence of carbonic anhydrase inhibition and in normal animals. 4) The CO2 output was measured directly during the hyperventilation which results from carbonic anhydrase inhibition, during the same hyperventilation in the normal animal and following carbonic anhydrase inhibition when the ventilation is held constant. These experiments demonstrate an immediate fall in CO2 output relative to the ventilation when carbonic anhydrase is inhibited, resulting in CO2 retention until a new steady state has been reached. An hypothesis is presented to explain the effect of carbonic anhydrase inhibition on CO2 transport. Submitted on March 28, 1958

Sweat suppression by forced breathing in man

1965 ◽  
Vol 20 (1) ◽  
pp. 134-136 ◽  
Author(s):  
Roy E. Albert
Keyword(s):  
Carbon Dioxide ◽  
Sweat Rate ◽  
Respiratory Alkalosis ◽  
Normal Male ◽  
Excess Carbon ◽  
Air Breathing ◽  
Thermal Sweating ◽  
Forced Air ◽  
Forced Breathing ◽  
Male Subjects

Thermal sweating from the forehead was suppressed by forced air breathing in two normal male subjects. The decreased sweat rate was associated with symptoms of respiratory alkalosis. This sweat suppression was blocked by the introduction of excess carbon dioxide into the respired gas. sweating and hyperventilation; hyperventilation and sweating; respiratory alkalosis and sweating Submitted on February 7, 1964

Effect of obesity on ventilatory adjustment to exercise

1963 ◽  
Vol 18 (1) ◽  
pp. 19-24 ◽  
Author(s):  
J. Howland Auchincloss ◽  
John Sipple ◽  
Robert Gilbert
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Treadmill Exercise ◽  
Ventilatory Response ◽  
Carbon Dioxide Production ◽  
Exercise Ventilation ◽  
Expired Gas ◽  
Obese Subjects ◽  
Oxygen Tensions ◽  
Alveolar Oxygen

The ventilatory response to treadmill exercise was studied in normal and obese subjects, with an analysis of both the steady and unsteady states of exercise. Ventilation, oxygen consumption, carbon dioxide production, respiratory quotient, and alveolar and mixed expired gas concentrations were measured directly or computed. During the steady state of exercise obese subjects increased their ventilation sufficiently to maintain normal alveolar carbon dioxide tensions. During the first 2 min of exercise hypoventilation was more pronounced in obese subjects and in certain individuals resulted in mild reductions in alveolar oxygen tensions. Obese individuals exercised less efficiently than nonobese as manifested by excessive energy expenditure in relation to weight. Steady-state exercise PaCoCo2 values were higher in those subjects previously shown to be relatively insensitive to inhalation of 5% CO2 but failed to correlate with the speed of ventilatory responsiveness.

THE EFFECT OF INDUCED HYPOXIA ON OXYGEN UPTAKE DURING MUSCULAR EXERCISE IN NORMAL SUBJECTS

1962 ◽  
Vol 40 (6) ◽  
pp. 717-726 ◽  
Author(s):  
R. F. Patrick Cronin ◽  
Donald J. MacIntosh
Keyword(s):  
Steady State ◽  
Oxygen Uptake ◽  
Linear Relationship ◽  
Normal Subjects ◽  
Work Load ◽  
Oxygen Mixture ◽  
Normal Male ◽  
Low Oxygen ◽  
Similar Work ◽  
Exercise Period

During the moderate exercise of treadmill walking, steady-state oxygen uptake bears a linear relationship to the work performed (i.e. to the slope of the treadmill), when the speed of walking is kept constant. Four normal male subjects were studied on the treadmill at several levels of exercise while they were breathing air and again while breathing a mixture of approximately 11% oxygen in nitrogen. An alteration in the linear relationship between oxygen uptake and work, established with the subjects breathing air, was observed when the subjects were restudied breathing 11% oxygen. In each case, this alteration indicated that the subject took up less oxygen while breathing a low-oxygen mixture despite the accomplishment of similar work loads. That this phenomenon is explicable on the basis of slower attainment of the steady state was excluded by prolonging each exercise period in two subjects. Another possible explanation, i.e. that the subjects effect greater utilization of anaerobic metabolic sources while hypoxic, was excluded by direct measurement of the oxygen debt after each period of exercise. It is concluded that exercising normal subjects exhibit an adaptive mechanism under conditions of induced hypoxia permitting reduced oxygen uptake for a given work load.

The Effect of Handrail Support on Oxygen Uptake During Steady-State Treadmill Exercise

2006 ◽  
Vol 26 (6) ◽  
pp. 391-394 ◽  
Author(s):  
Jennifer Berling ◽  
Carl Foster ◽  
Mark Gibson ◽  
Scott Doberstein ◽  
John Porcari
Keyword(s):  
Steady State ◽  
Oxygen Uptake ◽  
Treadmill Exercise

Effects of changes in level and pattern of breathing on the sensation of dyspnea

1990 ◽  
Vol 69 (4) ◽  
pp. 1290-1295 ◽  
Author(s):  
T. Chonan ◽  
M. B. Mulholland ◽  
M. D. Altose ◽  
N. S. Cherniack
Keyword(s):  
Steady State ◽  
Spontaneous Breathing ◽  
Minute Ventilation ◽  
Constant Level ◽  
Normal Male ◽  
Respiratory Effort ◽  
Breathing Frequency ◽  
Ventilatory Responses ◽  
End Tidal ◽  
Male Subjects

Breathing during hypercapnia is determined by reflex mechanisms but may also be influenced by respiratory sensations. The present study examined the effects of voluntary changes in level and pattern of breathing on the sensation of dyspnea at a constant level of chemical drive. Studies were carried out in 15 normal male subjects during steady-state hypercapnia at an end-tidal PCO2 of 50 Torr. The intensity of dyspnea was rated on a Borg category scale. In one experiment (n = 8), the level of ventilation was increased or decreased from the spontaneously adopted level (Vspont). In another experiment (n = 9), the minute ventilation was maintained at the level spontaneously adopted at PCO2 of 50 Torr and breathing frequency was increased or decreased from the spontaneously adopted level (fspont) with reciprocal changes in tidal volume. The intensity of dyspnea (expressed as percentage of the spontaneous breathing level) correlated with ventilation (% Vspont) negatively at levels below Vspont (r = -0.70, P less than 0.001) and positively above Vspont (r = 0.80, P less than 0.001). At a constant level of ventilation, the intensity of dyspnea correlated with breathing frequency (% fspont) negatively at levels below fspont (r = -0.69, P less than 0.001) and positively at levels above fspont (r = 0.75, P less than 0.001). These results indicate that dyspnea intensifies when the level or pattern of breathing is voluntarily changed from the spontaneously adopted level. This is consistent with the possibility that ventilatory responses to changes in chemical drive may be regulated in part to minimize the sensations of respiratory effort and discomfort.

Oxygen uptake and carbon dioxide elimination during epinephrine-induced arrhythmias in humans

1992 ◽  
Vol 6 (2) ◽  
pp. 237-240
Author(s):  
Yoshito Shiraishi ◽  
Yoshiki Nakajima ◽  
Jun-ichirou Yokoyama ◽  
Kazuyuki Ikeda
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Uptake ◽  
Carbon Dioxide Elimination
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