The effects of breathing a helium–oxygen gas mixture on maximal pulmonary ventilation and maximal oxygen consumption during exercise in acute moderate hypobaric hypoxia

The purpose of this study was to investigate changes in oxidative stress, arterial oxygen saturation (SaO2), blood pressure (BP), and heart rate (HR) during exercise in hypobaric hypoxia following acute dietary nitrate supplementation. Nine well-trained (maximal oxygen consumption, 60.8 ± 7.8 mL·kg−1·min−1) males (age, 29 ± 7 years) visited the laboratory on 3 occasions, each separated by 1 week. Visit 1 included a maximal aerobic cycling test and five 5-min increasing-intensity exercise bouts in a normobaric environment (1600 m). A single dose of either a nitrate-depleted placebo (PL) or a nitrate-rich beverage (NR; 12.8 mmol nitrate) was consumed 2.5 h prior to exercise during visits 2 and 3 (3500 m) in a double-blind, placebo-controlled, crossover study consisting of a 5-min cycling warm-up and 4 bouts, each 5 min in duration, separated by 4-min periods of passive rest. Exercise wattages were determined during visit 1 and corresponded to 25%, 40%, 50%, 60%, and 70% of normobaric maximal oxygen consumption. Catalase and 8-isoprostane were measured before and after exercise (immediately before and 1 h postexercise, respectively). NR increased plasma nitrite (1.53 ± 0.83 μmol·L−1) compared with PL (0.88 ± 0.56 μmol·L−1) (p < 0.05). In both conditions, postexercise (3500 m) 8-isoprostane (PL, 23.49 ± 3.38 to 60.90 ± 14.95 pg·mL−1; NR, 23.23 ± 4.12 to 52.11 ± 19.76 pg·mL−1) and catalase (PL, 63.89 ± 25.69 to 128.15 ± 41.80 mmol·min−1·mL−1; NR, 78.89 ± 30.95 to 109.96 ± 35.05 mmol·min−1·mL−1) were elevated compared with baseline resting values (p < 0.05). However, both 8-isoprostane and catalase were similar in the 2 groups (PL and NR) (p = 0.217 and p = 0.080, respectively). We concluded that an acute, pre-exercise dose of dietary nitrate yielded no beneficial changes in oxidative stress, SaO2, BP, or HR in healthy, aerobically fit men exercising at 3500 m.

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Hatha Yoga Practices: Energy Expenditure, Respiratory Changes and Intensity of Exercise

Evidence-based Complementary and Alternative Medicine ◽

10.1093/ecam/neq046 ◽

2011 ◽

Vol 2011 ◽

pp. 1-12 ◽

Cited By ~ 24

Author(s):

Uday Sankar Ray ◽

Anjana Pathak ◽

Omveer Singh Tomer

Keyword(s):

Oxygen Consumption ◽

Energy Expenditure ◽

Exercise Intensity ◽

Lactate Threshold ◽

Pulmonary Ventilation ◽

Maximal Oxygen Consumption ◽

Average Energy ◽

Practice Session ◽

Metabolic Equivalents ◽

Intensity Of Exercise

The aim of this study was to critically observe the energy expenditure, exercise intensity and respiratory changes during a full yoga practice session. Oxygen consumption (), carbon dioxide output (), pulmonary ventilation (E), respiratory rate (Fr) and tidal volume (VT), were measured in 16 physical posture (asanas), five yoga breathing maneuvers (BM) and two types of meditation. Twenty male (age 27.3 ± 3.5 years, height 166.6 ± 5.4 cm and body weight 58.8 ± 9.6 kg) yoga instructors were studied. Their maximal oxygen consumption () was recorded. The exercise intensity in asanas was expressed in percentage . In asanas, exercise intensity varied from 9.9 to 26.5% of . Highest energy cost was 3.02 kcal min-1. In BM highest E was 53.7 ± 15.5 l min-1. VT was 0.97 ± 0.59, 1.41 ± 1.27 and 1.28 ± l/breath with corresponding Fr of 14.0 ± 5.3, 10.0 ± 6.35, 10.0 ± 5.8 breaths/min. Average energy expenditure in asanas, BM and meditation were 2.29, 1.91 and 1.37 kcal min-1, respectively. Metabolic rate was generally in the range of 1-2 metabolic equivalents (MET) except in three asanas where it was >2 MET. was 0.27 ± 0.05 and 0.24 ± 0.04 l min-1in meditation and Shavasana, respectively. Although yogic practices are low intensity exercises within lactate threshold, physical performance improvement is possible owing to both better economy of breathing by BM and also by improvement in cardiovascular reserve. Other factors such as psycho-physiological and better relaxation may contribute to it.

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Relationship between resting ventilatory chemosensitivity and maximal oxygen uptake in moderate hypobaric hypoxia

Journal of Applied Physiology ◽

10.1152/japplphysiol.00153.2007 ◽

2007 ◽

Vol 103 (4) ◽

pp. 1221-1226 ◽

Cited By ~ 12

Author(s):

Takeshi Ogawa ◽

Keiji Hayashi ◽

Masashi Ichinose ◽

Takeshi Nishiyasu

Keyword(s):

Hypobaric Hypoxia ◽

Pulmonary Ventilation ◽

Respiratory Response ◽

Distance Runners ◽

Long Distance ◽

Oxyhemoglobin Saturation ◽

Ventilatory Responses ◽

Moderate Hypobaric Hypoxia ◽

Normobaric Normoxia ◽

Rebreathing Method

This study tested the hypothesis that the extent of the decrement in V̇o2max and the respiratory response seen during maximal exercise in moderate hypobaric hypoxia (H; simulated 2,500 m) is affected by the hypoxia ventilatory and hypercapnia ventilatory responses (HVR and HCVR, respectively). Twenty men (5 untrained subjects, 7 long distance runners, 8 middle distance runners) performed incremental exhaustive running tests in H and normobaric normoxia (N) condition. During the running test, V̇o2, pulmonary ventilation (V̇e) and arterial oxyhemoglobin saturation (SaO2) were measured, and in two ventilatory response tests performed during N, a rebreathing method was used to evaluate HVR and HCVR. Mean HVR and HCVR were 0.36 ± 0.04 and 2.11 ± 0.2 l·min−1·mmHg−1, respectively. HVR correlated significantly with the percent decrements in V̇o2max (%dV̇o2max), SaO2 [%dSaO2 = (N−H)·N−1·100], and V̇e/V̇o2 seen during H condition. By contrast, HCVR did not correlate with any of the variables tested. The increment in maximal V̇e between H and N significantly correlated with %dV̇o2max. Our findings suggest that O2 chemosensitivity plays a significant role in determining the level of exercise hyperventilation during moderate hypoxia; thus, a higher O2 chemosensitivity was associated with a smaller drop in V̇o2max and SaO2 under those conditions.

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Oral versus Nasal Breathing during Moderate to High Intensity Submaximal Aerobic Exercise

International Journal of Kinesiology and Sports Science ◽

10.7575//aiac.ijkss.v.5n.1p.8 ◽

2017 ◽

Vol 5 (1) ◽

pp. 8 ◽

Cited By ~ 2

Author(s):

Chase O. LaComb ◽

Richard D. Tandy ◽

Szu Ping Lee ◽

John C. Young ◽

James W. Navalta

Keyword(s):

Carbon Dioxide ◽

Oxygen Consumption ◽

Aerobic Exercise ◽

Repeated Measures ◽

Pulmonary Ventilation ◽

Maximal Oxygen Consumption ◽

Submaximal Exercise ◽

Nasal Breathing ◽

Oral Breathing ◽

Submaximal Aerobic Exercise

Introduction: When comparing oral breathing versus nasal breathing, a greater volume of air can be transported through the oral passageway but nasal breathing may also have benefits at submaximal exercise intensities. Purpose: The purpose of this study was to determine breathing efficiency during increasing levels of submaximal aerobic exercise. Methods: Nineteen individuals (males N=9, females N=10) completed a test for maximal oxygen consumption (VO2max) and on separate days 4-min treadmill runs at increasing submaximal intensities (50%, 65%, and 80% of VO2max) under conditions of oral breathing or nasal breathing. Respiratory (respiration rate [RR], pulmonary ventilation [VE]), metabolic (oxygen consumption [VO2], carbon dioxide production [VCO2]) and efficiency measures (ventilatory equivalents for oxygen [Veq×O2-1] and carbon dioxide [Veq×CO2-1] were obtained. Data were analyzed utilizing a 2 (sex) x 2 (condition) x3 (intensity) repeated measures ANOVA with significance accepted at p≤0.05. Results: Significant interactions existed between breathing mode and intensity such that oral breathing resulted in greater RR, VE, VO2, and VCO2 at all three submaximal intensities (p<.05). Veq×O2-1 and Veq×CO2-1 presented findings that nasal breathing was more efficient than oral breathing during the 65% and 80% VO2max intensities (p<0.05). Conclusion: Based on this analysis, oral breathing provides greater respiratory and metabolic volumes during moderate and moderate-to-high submaximal exercise intensities, but may not translate to greater respiratory efficiency. However when all variables are considered together, it is likely that oral breathing represents the more efficient mode, particularly at higher exercise intensities.

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