Respiratory gas exchange in exercise during helium-oxygen breathing

Murphy, Thomas M.; Clark, W. H.; Buckingham, I. P. B.; Young, W. A.

doi:10.1152/jappl.1969.26.3.303

Cited by 31 publications

(21 citation statements)

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“…A significant reduction in the O 2 cost of cycling, obtained by normoxic helium breathing during constant work rate submaximal exercise, has been described before in normal subjects (Murphy et al 1969;Cross et al 2010b) and in COPD patients (Chiappa et al 2009). It should be noted that, even after decreasing in He-O 2 , the O 2 cost of cycling in the population of the present study (see the "gain" data in Table 3) was still at least 30 % higher than "normal" (see Whipp et al 2002).…”

Section: Discussionmentioning

confidence: 56%

“…Previous studies carried out on . V O 2 peak with normoxic helium breathing in normal subjects observed no changes (Esposito and Ferretti 1997), an increase (Brice and Welch 1983;Powers et al 1986) or a decrease (Murphy et al 1969) of the variable. The present study does not allow further insights into the possible reasons for these conflicting results.…”

Section: Discussionmentioning

confidence: 84%

“…Also the calibration of the pneumotachograph was carried out by utilizing the experimental gas mixture (AIR or He-O 2 ). The possibility of this technical limitation was not mentioned in the studies by Brice and Welch (1983), Chiappa et al (2009), Esposito and Ferretti (1997), Louvaris et al (2012), Murphy et al (1969), Powers et al (1986).…”

Section: Discussionmentioning

confidence: 98%

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Acute respiratory muscle unloading by normoxic helium–O2 breathing reduces the O2 cost of cycling and perceived exertion in obese adolescents

et al. 2014

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Section: Discussionmentioning

confidence: 56%

Section: Discussionmentioning

confidence: 84%

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Acute respiratory muscle unloading by normoxic helium–O2 breathing reduces the O2 cost of cycling and perceived exertion in obese adolescents

et al. 2014

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“…The reduction in RV induced by He-Oµ breathing can be related to the combined effects of lower density and higher viscosity of He with respect to Nµ (Murphy et al 1969;Papamoschou, 1995). At a given Reynolds number, all other variables being constant, gas flow is inversely proportional to the ratio of inertial to viscous forces.…”

Section: Discussionmentioning

confidence: 99%

“…In fact in the horse, He-Oµ breathing had no effect on ýOµ,max in normoxia (Erickson et al 1994), but increased (Erickson et al 1995) ýOµ,max in hypoxia . As far as humans are concerned, He-Oµ breathing has been reported to increase (Robertson & McRae, 1966;Brice & Welch, 1983), decrease (Murphy, Clark, Buckingham & Young, 1969;Spitler, Horvath, Kobayashi & Wagner, 1980) or have no effects (Bowers & Fox, 1967) on ýOµ,max in normoxia. No previous studies, to our knowledge, have investigated the effects of He-Oµ breathing on ýOµ,max in humans exposed to acute hypoxia.…”

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confidence: 99%

The Effects of Breathing He–O₂ Mixtures on Maximal Oxygen Consumption in Normoxic and Hypoxic Men

Esposito¹,

Ferretti²

1997

The Journal of Physiology

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The hypothesis that the ventilatory resistance to O2 flow (RV) does limit maximal O2 consumption (V̇O2 max) in hypoxia, but not in normoxia, at least in non‐athletic subjects, was tested. RV was reduced by using He–O2 mixtures. V̇O2, max was measured during graded cyclo‐ergometric exercise in eight men (aged 30 ± 3 years) who breathed N2–O2 and He–O2 mixtures in normoxia (inspired oxygen fraction (FI,O2= 0.21) and hypoxia (FI,O2= 0.11). O2 consumption, expired and alveolar ventilations (V̇E and V̇A, respectively), blood lactate and haemoglobin concentrations, heart rate and arterial oxygen saturation (Sa,O2) were determined at the steady state of each work load. Arterial O2 and CO2 partial pressures (Pa,O2) and Pa,CO2, respectively) were measured at rest and at the end of the highest work load. Maximal V̇E and V̇A were significantly increased by He—O2 breathing in normoxia (+27 and +18%, respectively), without significant changes in Pa, O2, Sa, O2V̇O2, max In hypoxia, V̇E and V̇A increased (+31 and +24%, respectively), together with Pa,O2 (+17%), Sa, O2 (+6%) and V̇O2, max (+14%). The results support the hypothesis that the role of RV in limiting V̇O2,max is negligible in normoxia. In hypoxia, the finding that higher V̇E and V̇A values during He–O2 breathing led to higher V̇O2,max values suggests a greater role of RV as a limiting factor. It is unclear whether the finding that the V̇O2 max values were the same during He–O2 and N2–O2 breathing in normoxia is due to a non‐linear response of the O2 transfer system, as previously proposed.

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Effects of breathing a normoxic helium mixture on exercise tolerance‐of patients with cystic fibrosis

Martı́n

Day

Ward

et al. 1994

Pediatric Pulmonology

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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)

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Respiratory gas exchange in exercise during helium-oxygen breathing

Cited by 31 publications

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Acute respiratory muscle unloading by normoxic helium–O2 breathing reduces the O2 cost of cycling and perceived exertion in obese adolescents

Acute respiratory muscle unloading by normoxic helium–O2 breathing reduces the O2 cost of cycling and perceived exertion in obese adolescents

The Effects of Breathing He–O₂ Mixtures on Maximal Oxygen Consumption in Normoxic and Hypoxic Men

Effects of breathing a normoxic helium mixture on exercise tolerance‐of patients with cystic fibrosis

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Respiratory gas exchange in exercise during helium-oxygen breathing

Cited by 31 publications

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Acute respiratory muscle unloading by normoxic helium–O2 breathing reduces the O2 cost of cycling and perceived exertion in obese adolescents

Acute respiratory muscle unloading by normoxic helium–O2 breathing reduces the O2 cost of cycling and perceived exertion in obese adolescents

The Effects of Breathing He–O2 Mixtures on Maximal Oxygen Consumption in Normoxic and Hypoxic Men

Effects of breathing a normoxic helium mixture on exercise tolerance‐of patients with cystic fibrosis

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The Effects of Breathing He–O₂ Mixtures on Maximal Oxygen Consumption in Normoxic and Hypoxic Men