[Consciousness and will in breathing].
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Breathing Exercises↗
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Pulmonary profiling in exercise.
The role of the lungs during exercise, the effect of physical training on lung function, and the attributes of lung function that are important for superior athletic performance are discussed. Also considered is the role of exercise in two common lung disorders, asthma and chronic obstructive pulmonary disease.
Asthma, Exercise-Induced↗
[Blockade of exercise-induced bronchial asthma by fenoterol].
The bronchoconstrictor response to cold air breathing during exercise shows a wide interindividual variation in asthmatic patients. We investigated whether the protective effect of a single, inhaled dose of 0.2 mg fenoterol powder is dependent on the severity of airways obstruction, following placebo pretreatment of an inhalative thermal burden precisely matched in terms of respiratory heat exchange. In ten asthmatic patients 0.2 mg fenoterol powder or placebo were administered via an inhalator in a single blind and random order fashion on separate days. Lung function was measured before and 30 min after treatment (baseline value) and 3, 10, 15 and 30 min after an inhalative provocation consisting of cold air breathing during exercise. After placebo the maximal increase of airway resistance compared to the baseline value ranged from 682% to 50% (means +/- SD: 344.1 +/- 312.2) whereas fenoterol shifted the corresponding data to 58% and -23.0% (means +/- SD: 13.4 +/- 29.2). The protective effect of fenoterol did not depend on the reactivity of the airways to the stimulus applied. The results indicate that the inhalative pretreatment with 0.2 mg fenoterol powder is sufficient to block exercise-induced asthma even in those patients whose airways are highly sensitive to respiratory heat loss.
Adolescent↗
Cardiac output in exercise by impedance cardiography during breath holding and normal breathing.
Estimation of cardiac output by impedance cardiography (QZ) in exercise during normal breathing (NB) has been limited by motion artifact. Our objective was to obtain readable impedance cardiograms on five subjects during upright cycle exercise at 0, 50, 100, 150, and 200 W to permit comparisons of QZ during NB, expiratory breath hold (EXP) and inspiratory breath hold (INSP). Q was also determined using an equilibration CO2 rebreathing method [Q(RB)]. QZ during NB exceeded EXP QZ at 100, 150, and 200 W, and exceeded INSP QZ at 100 W (P less than 0.05). The low EXP QZ values were due to a significantly lower stroke volume at 100, 150, and 200 W (P less than 0.05). For the INSP QZ at 100 W, heart rate was lower than during EXP (P less than 0.05). Regression of QZ (NB) against Q(RB) resulted in a linear relationship (r = 0.93) over the range of Q = 7-26 1/min. The slope of the regression differed significantly from 1.0 (P less than 0.05). We conclude that QZ values obtained during EXP or INSP should not be assumed to represent QZ during NB, at least at work rates greater than 50 W. A consequence of the linear relationship between QZ(NB) and Q(RB) over the range of 0-200 W is that estimates of CO2 rebreathing cardiac output can be obtained by impedance cardiography if QZ is adjusted using an appropriate empirical factor.
Adult↗
Breath holding at beginning of exercise.
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Breath Holding↗
Time course of ozone-induced changes in breathing pattern in healthy exercising humans.
We examined the time course of O3-induced changes in breathing pattern in 97 healthy human subjects (70 men and 27 women). One- to five-minute averages of breathing frequency (f(B)) and minute ventilation (Ve) were used to generate plots of cumulative breaths and cumulative exposure volume vs. time and cumulative exposure volume vs. cumulative breaths. Analysis revealed a three-phase response; delay, no response detected; onset, f(B) began to increase; response, f(B) stabilized. Regression analysis was used to identify four parameters: time to onset, number of breaths at onset, cumulative inhaled dose of ozone at onset of O3-induced tachypnea, and the percent change in f(B). The effect of altering O3 concentration, Ve, atropine treatment, and indomethacin treatment were examined. We found that the lower the O3 concentration, the greater the number of breaths at onset of tachypnea at a fixed ventilation, whereas number of breaths at onset of tachypnea remains unchanged when Ve is altered and O3 concentration is fixed. The cumulative inhaled dose of O3 at onset of tachypnea remained constant and showed no relationship with the magnitude of percent change in f(B). Atropine did not affect any of the derived parameters, whereas indomethacin did not affect time to onset, number of breaths at onset, or cumulative inhaled dose of O3 at onset of tachypnea but did attenuate percent change in f(B). The results are discussed in the context of dose response and intrinsic mechanisms of action.
Adolescent↗
Influence of exercise and CO2 on breathing pattern of normal man.
Ventilatory patterns during rest, CO2 inhalation (2, 3, and 4%) and three levels of exercise were analyzed in supine men using a canopy system for noninvasive measurements. Changes in tidal volume (VT) and breathing frequency (f) with equal increases in minute ventilation (VE) differed significantly during exercise and CO2 inhalation. Increases in VE during exercise was accompanied by increases in VT and f. During CO2 inhalation, the change in frequency was less than during exercise. However, when analyzed in terms of inspiratory flow (VT/TI) and inspiratory duty cycle (TI/Ttot), the response to both stimuli was similar. With increases to twice control VE both TI/Ttot and VT/VI increased. Thereafter only VTTI increased with increasing VE. At rest, inspiratory time on a breath by breath basis increased minimally with VT, while changes in inspiratory flow accounted for the variability in VT. These two respiratory stimulants appear to increase ventilation through different mechanisms when analyzed in terms of VT and f. However, changes in inspiratory flow and duty cycle are similar in both.
Adult↗
Effect of mouthpiece breathing on cardiorespiratory response to intense exercise.
Use of mouthpiece and noseclips after breathing pattern at rest and during moderate exercise. Our purpose was to extend observations on mouthpiece breathing to its effects on the cardiorespiratory response to intense exercise and to develop and validate an algorithm for computer-assisted analysis of breathing pattern recorded with respiratory inductive plethysmography. Six normal men performed incremental bicycle exercise to volitional exhaustion on two occasions with and without mouthpiece and noseclip. ECG and breathing pattern recorded with a respiratory inductive plethysmograph were analyzed manually and with computer assistance. Mouthpiece breathing increased tidal volume and respiratory cycle time by up to 63 and 33% respectively (p < 0.02) during mild exercise, but it did not alter performance, heart rate, or breathing pattern at maximal exercise. Mean differences between inductive plethysmographic and spirometric tidal volumes were < 5% during validation at rest and maximal exercise. Application of the proposed algorithm for semiautomatic breathing pattern analysis provided significant time savings with no loss in precision compared with manual analysis. In conclusion, in normal men, performance and breathing pattern during maximal exercise are not altered by a mouthpiece and noseclip, and accurate computer-assisted measurement of ventilation from external transducers may be performed even during intense exercise.
Adult↗
Effects of breathing a normoxic helium mixture on exercise tolerance of patients with cystic fibrosis.
Breathing helium-oxygen (He-O2) mixtures of 20.9% O2/79.1% He has been shown to increase exercise ventilation and peak oxygen uptake in healthy subjects. The improved exercise performance is thought to be due to the reduced density of He-O2 compared to air and the resulting increases in ventilation. Patients with cystic fibrosis (CF) frequently have abnormal pulmonary function test results, low exercise ventilations and diminished exercise tolerance. This led to the hypothesis that in CF the exercise tolerance of patients might improve when breathing He-O2. To test this hypothesis, 11 patients with CF or mild to severe airway obstruction performed spirometry and progressive maximal exercise tests while breathing air or He-O2. The He-O2 mixture significantly increased (P < 0.05) forced expiratory volume in 1 sec (FEV1) by 8.2%, peak expired flow by 39%, and maximal voluntary ventilation (MVV) by 17.9% compared to air, while forced vital capacity (FVC) and forced mid-expiratory flow rate (FEF25-75%) were unchanged by breathing He-O2. Ventilation and oxygen uptake at matched submaximal power outputs were not increased while breathing He-O2, nor were peak exercise ventilation (VEpeak) or peak exercise oxygen uptake (VO2peak). Estimated hemoglobin saturation and total exercise time were also unchanged during He-O2 breathing. However, there was a trend for the subjects with the better FEV1 to increase VO2peak. Increases in VO2peak when breathing He-O2 and air were correlated (r = 0.67, P < 0.05) with the percent of predicted FEV1 values. Still, in the 11 patients as a group, breathing He-O2 did not significantly improve VO2peak, VEpeak, or exercise tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Effects of acetate infusion and hyperoxia on muscle substrate phosphorylation after onset of moderate exercise.
This study investigated whether increased muscle acetylcarnitine provision (acetate infusion) or hyperoxia (100% O(2)) would increase the rate of oxidative phosphorylation and reduce the reliance on muscle substrate phosphorylation after the onset of moderate exercise. Eight subjects completed three randomized trials, each separated by 1 wk: 1) saline infusion for 1 h before exercise, while breathing room air for 20 min before exercise and during 120 s of cycling at 65% maximal exercise (VO(2 max)) (CON), 2) saline infusion with 4 mmol/kg body wt sodium acetate, while breathing room air before and during exercise (ACE), and 3) saline infusion and breathing 100% O(2) before and during exercise (HYP). Muscle biopsies were sampled at rest and after 30 and 120 s of exercise. ACE increased muscle acetyl-CoA and acetylcarnitine contents at rest vs. CON and HYP [22.9 +/- 2.8 vs. 8.9 +/- 2.4 and 10.5 +/- 1.8 micromol/kg dry muscle (dm); 11.0 +/- 1.2 vs. 3.5 +/- 1.3 and 4.0 +/- 1.2 mmol/kg dm]. Acetate had no effect on resting pyruvate dehydrogenase activity in the active form (PDH(a)) among CON, ACE, and HYP. During exercise, acetyl-CoA and acetylcarnitine were unchanged in ACE but increased over time in the CON and HYP trials, and PDH(a) increased similarly in all trials. Muscle phosphocreatine use, lactate accumulation, and substrate phosphorylation energy provision after 30 or 120 s of exercise were similar in all trials. In summary, increased acetylcarnitine availability did not accelerate the rate of oxidative phosphorylation at the onset of exercise, suggesting that this is not a site of extra substrate. Hyperoxia had no effect on substrate phosphorylation, suggesting that O(2) availability does not limit oxidative phosphorylation at the onset of moderate exercise.
Acetates↗
[METHODOLOGICAL PRINCIPLES OF RESPIRATORY EXERCISES FOR SCOLIOTIC CHILDREN AFTER SURGICAL THERAPY].
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Breathing Exercises↗
Breath hydrogen testing as a physiology laboratory exercise for medical students.
Breath hydrogen testing (BHT) is a simple and reliable method for identifying impaired carbohydrate absorption. We describe a laboratory exercise in physiology for medical students using BHT as the teaching tool. The students collect fasting samples of expired air from each other using a simple nasal prong technique. They then drink one of several different aqueous carbohydrate solutions. Additional samples of expired air are collected by the students at 90 and 120 min after substrate ingestion and are analyzed by gas chromatography. Between sampling periods, discussions of digestive physiology are provided by the faculty. Students tabulate their BHT results as well as recording any symptoms using a standard scoring system. A total of 460 students have participated. We found that the percentage of students who malabsorbed a given substrate was similar each year. The results obtained in these student exercises closely parallel those reported in the literature. We conclude that BHT is an excellent teaching tool for illustrating carbohydrate digestion and absorption, even when performed by minimally trained subjects.
Animals↗
Hyperoxia improves maximal exercise with the self-contained breathing apparatus (SCBA).
The effects of hyperoxia on maximal exercise while breathing from a self-contained breathing apparatus (SCBA) were studied in 25 males. Each participant completed three graded exercise tests (GXT) for the assessment of maximal oxygen uptake (VO(2max)): two with 20.95 +/- 0.28% O(2) and the third (GXT(40)) while breathing hyperoxia (40.64 +/- 1.29% O(2)). No significant differences were found between the two normoxic tests, except for a 16W increase in maximal power output (PO(max)) in the second trial (GXT(21)). Compared to GXT(21), hyperoxia significantly increased VO(2max) and PO(max) by 10.0 +/- 3.8% and 10.2 +/- 7.1%, respectively. This was likely due to an increase in O(2) delivery as suggested by the significantly higher oxyhemoglobin saturation. The increase in VO (2max) with hyperoxia was similar to the increase in carbon dioxide production (9.3 +/- 6.5%). No other significant di.fferences were found at maximal exercise. However, at the intensity that elicited VO(2max) in GXT(21), pulmonary ventilation and SCBA mask pressure were significantly lower during GXT(40), suggesting a decrease in the work of breathing. These findings could have significant implications for occupations that involve heavy work with SCBA.
Adult↗
Ventilatory and gas exchange responses under spontaneous and fixed breathing modes during arm exercise.
To evaluate the difference of ventilatory and gas exchange response differences between arm and leg exercise, six healthy young men underwent ramp exercise testing at a rate of 15 W.min-1 on a cycle ergometer separately under either spontaneous (SPNT) or fixed (FIX) breathing modes, respectively. Controlled breathing was defined as a breathing frequency (fb; 30 breaths.min-1) which was neither equal to, nor a multiple of, cranking frequency (50 rev.min-1) to prevent coupling of locomotion and respiratory movement, i.e., so-called locomotor-respiratory coupling (LRC). Breath-by-breath oxygen uptake (VO2), ventilation (VE), CO2 output (VCO2), tidal volume (VT), fb and end-tidal PCO2 (PETCO2) were determined using a computerized metabolic cart. Arm exercise engendered a higher level of VO2 at each work rate than leg exercise under both FIX and SPNT conditions. However, FIX did not notably affect the VO2 response during either arm or leg exercise at each work rate compared to SPNT. During SPNT a significantly higher fb and lower PETCO2 during arm exercise was found compared with leg exercise up to a fb of 30 breaths.min-1 while VE and VT were nearly the same. During fixed breathing when fb was fixed at a higher rate than during SPNT, a significantly lower PETCO2 was observed during both exercise modes. These results suggest that: 1) FIX breathing does not affect the VO2 response during either arm or leg exercise even when non-synchronization between limb locomotion movement and breathing rate was adopted; 2) at a fb of 30 breaths.min-1 FIX breathing induced a hyperventilation resulting in a lower PETCO2 which was not associated with the metabolic rate during either arm or leg exercise, showing that VE during only leg exercise under the FIX condition was significantly higher than under the SPNT condition.
Adult↗
Work of breathing in dog during exercise.
In six dogs trained to wear a mask and to swallow an esophageal balloon, the dynamic work of breathing (Wdyn) was measured while the animals ran on a treadmill at different intensities (7-13 km.h-1,+10%). Wydn (kg.m.min-1) increased with ventilation (VE, 1.min-1) according to Wdyn = 0.308.10(-2) VE2 + 0.0098.10(-2).VE3. However, if the exercise was prolonged so that the body temperature rose above approximately 39 degrees C, Wdyn, for a given ventilation, decreased; and hence Wdyn = 0.253.10(-2).VE2 -- 0.0011.10(-2).VE3. Similar observations have been made on another dog heated from an external source. From this finding it seems that during exercise, when the temperature rises and the ventilation increases to dissipate heat, the airway size, at least in some portion of the respiratory tract, increases markedly and therefore the cost of breathing is greatly diminished. This mechanism would save oxygen for the exercising limb muscles when exercise has to be continued for an extended time.
Airway Resistance↗
Blood lactate disappearance during breathing hyperoxic gas after exercise in two different physical fitness groups--on the work load fixed at 70% VO2max.
The purpose of this study is to evaluate effects of breathing hyperoxic gas on blood lactate disappearance after submaximal exercise in two different physical fitness groups and to clarify the most effective oxygen concentration in each group. Fourteen healthy male students participated as subjects in this study. They were divided in two groups by difference in their anaerobic threshold (AT). Seven males were treated as Higher AT group and the others as Lower AT group. Subjects wore a T-shirt, short pants and sports shoes and performed three sessions; each consisting of five minutes of exercise and six minutes of rest, at a workload of 70%VO2max on a bicycle ergometer. Hyperoxic gas was breathed only during recovery periods. Oxygen rates of 21, 30, 40, 60, 80 and 100% in inspired gas were employed. According to the results of blood lactate (BLA), the most effective oxygen condition on BLA disappearance was obtained over 60% in Higher AT group and at 30% oxygen in Lower AT group. Thus, it was especially noteworthy that the effects of hyperoxic gas in Higher AT group were different from those of Lower AT group. It is thought that the effects of breathing hyperoxic gas were dependent on physical fitness, which have caused many reports to be in conflict hitherto.
Adult↗