1
|
Ferretti G, Strapazzon G. A revision of maximal oxygen consumption and exercise capacity at altitude 70 years after the first climb of Mount Everest. J Physiol 2024. [PMID: 38299739 DOI: 10.1113/jp285606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 01/03/2024] [Indexed: 02/02/2024] Open
Abstract
On the 70th anniversary of the first climb of Mount Everest by Edmund Hillary and Tensing Norgay, we discuss the physiological bases of climbing Everest with or without supplementary oxygen. After summarizing the data of the 1953 expedition and the effects of oxygen administration, we analyse the reasons why Reinhold Messner and Peter Habeler succeeded without supplementary oxygen in 1978. The consequences of this climb for physiology are briefly discussed. An overall analysis of maximal oxygen consumption (V ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ ) at altitude follows. In this section, we discuss the reasons for the non-linear fall ofV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ at altitude, we support the statement that it is a mirror image of the oxygen equilibrium curve, and we propose an analogue of Hill's model of the oxygen equilibrium curve to analyse theV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ fall. In the following section, we discuss the role of the ventilatory and pulmonary resistances to oxygen flow in limitingV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ , which becomes progressively greater while moving toward higher altitudes. On top of Everest, these resistances provide most of theV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ limitation, and the oxygen equilibrium curve and the respiratory system provide linear responses. This phenomenon is more accentuated in athletes with elevatedV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ , due to exercise-induced arterial hypoxaemia. The large differences inV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ that we observe at sea level disappear at altitude. There is no need for a very highV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ at sea level to climb the highest peaks on Earth.
Collapse
Affiliation(s)
- Guido Ferretti
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Giacomo Strapazzon
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- SIMeM Italian Society of Mountain Medicine, Padova, Italy
| |
Collapse
|
2
|
The effects of cloth face masks on cardiorespiratory responses and VO 2 during maximal incremental running protocol among apparently healthy men. Sci Rep 2022; 12:22292. [PMID: 36566337 PMCID: PMC9789509 DOI: 10.1038/s41598-022-26857-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 12/21/2022] [Indexed: 12/25/2022] Open
Abstract
We aimed to determine the effects of wearing a cloth face mask on cardiorespiratory response, peak oxygen uptake (Vo2), respiratory muscle effort, and exercise tolerance during incremental exercise. The study had a randomized crossover design: 11 apparently healthy young men performed the Bruce protocol treadmill test in two conditions, wearing a cloth face mask (CFM) and without CFM (CON), in random order. Minute ventilation and oxygen uptake were measured using a mass spectrometry metabolic analyzer; cardiac output (CO) was measured using an impedance CO monitor; and mouth pressure (Pm) was measured and calculated as an integral Pm to assess respiratory muscle effort. Maximal minute ventilation was 13.4 ± 10.7% lower in the CFM condition than in the CON condition (P < 0.001). The peak Vo2 (52.4 ± 5.6 and 55.0 ± 5.1 mL/kg/min in CFM and CON, respectively) and CO were not significantly different between the two conditions. However, the integral value of Pm was significantly higher (P = 0.02), and the running time to exhaustion was 2.6 ± 3.2% lower (P = 0.02) in the CFM condition than in the CON condition. Our results suggest that wearing a cloth face mask increased respiratory muscle effort and decreased ventilatory volume in healthy young men; however, Vo2 remained unchanged. Exercise tolerance also decreased slightly.
Collapse
|
3
|
Cao Y, Fujii N, Fujimoto T, Lai YF, Ogawa T, Hiroyama T, Enomoto Y, Nishiyasu T. CO 2-Enriched Air Inhalation Modulates the Ventilatory and Metabolic Responses of Endurance Runners During Incremental Running in Hypobaric Hypoxia. High Alt Med Biol 2022; 23:125-134. [PMID: 35613387 DOI: 10.1089/ham.2021.0114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cao, Yinhang, Naoto Fujii, Tomomi Fujimoto, Yin-Feng Lai, Takeshi Ogawa, Tsutomu Hiroyama, Yasushi Enomoto, and Takeshi Nishiyasu. CO2-enriched air inhalation modulates the ventilatory and metabolic responses of endurance runners during incremental running in hypobaric hypoxia. High Alt Med Biol. 23:125-134, 2022. Aim: We measured the effects of breathing CO2-enriched air on ventilatory and metabolic responses during incremental running exercise under moderately hypobairc hypoxic (HH) conditions. Materials and Methods: Ten young male endurance runners [61.4 ± 6.0 ml/(min·kg)] performed incremental running tests under three conditions: (1) normobaric normoxia (NN), (2) HH (2,500 m), and (3) HH with 5% CO2 inhalation (HH+CO2). The test under NN was always performed first, and then, the two remaining tests were completed in random and counterbalanced order. Results: End-tidal CO2 partial pressure (55 ± 3 vs. 35 ± 1 mmHg), peak ventilation (163 ± 14 vs. 152 ± 12 l/min), and peak oxygen uptake [52.3 ± 5.5 vs. 50.5 ± 4.9 ml/(min·kg)] were all higher in the HH+CO2 than HH trial (all p < 0.01), respectively. However, the duration of the incremental test did not differ between HH+CO2 and HH trials. Conclusion: These data suggest that chemoreflex activation by breathing CO2-enriched air stimulates breathing and aerobic metabolism during maximal intensity exercise without affecting exercise performance in male endurance runners under a moderately hypobaric hypoxic environment.
Collapse
Affiliation(s)
- Yinhang Cao
- School of Physical Education and Sport Training, Shanghai University of Sport, Shanghai, China.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Tomomi Fujimoto
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan.,Department of Health and Sports, Niigata University of Health and Welfare, Niigata, Japan
| | - Yin-Feng Lai
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Takeshi Ogawa
- Division of Art, Music, and Physical Education, Osaka Kyoiku University, Osaka, Japan
| | - Tsutomu Hiroyama
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Yasushi Enomoto
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| |
Collapse
|
4
|
Ogawa T, Nagao M, Fujii N, Nishiyasu T. Effect of inspiratory muscle-loaded exercise training on peak oxygen uptake and ventilatory response during incremental exercise under normoxia and hypoxia. BMC Sports Sci Med Rehabil 2020; 12:25. [PMID: 32322396 PMCID: PMC7161168 DOI: 10.1186/s13102-020-00172-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 03/25/2020] [Indexed: 11/29/2022]
Abstract
Background Although numerous studies have reported the effect of inspiratory muscle training for improving exercise performance, the outcome of whether exercise performance is improved by inspiratory muscle training is controversial. Therefore, this study investigated the influence of inspiratory muscle-loaded exercise training (IMLET) on peak oxygen uptake (VO2peak), respiratory responses, and exercise performance under normoxic (N) and hypoxic (H) exercise conditions. We hypothesised that IMLET enhances respiratory muscle strength and improves respiratory response, thereby improving VO2peak and work capacity under H condition. Methods Sixteen university track runners (13 men and 3 women) were randomly assigned to the IMLET (n = 8) or exercise training (ET) group (n = 8). All subjects underwent 4 weeks of 20-min 60% VO2peak cycling exercise training, thrice per week. IMLET loaded 50% of maximal inspiratory pressure during exercise. At pre- and post-training periods, subjects performed exhaustive incremental cycling under normoxic (N; 20.9 ± 0%) and hypoxic (H; 15.0 ± 0.1%) conditions. Results Although maximal inspiratory pressure (PImax) significantly increased after training in both groups, the extent of PImax increase was significantly higher in the IMLET group (from 102 ± 20 to 145 ± 26 cmH2O in IMLET; from 111 ± 23 to 127 ± 23 cmH2O in ET; P < 0.05). In both groups, VO2peak and maximal work load (Wmax) similarly increased both under N and H conditions after training (P < 0.05). Further, the extent of Wmax decrease under H condition was lower in the IMLET group at post-training test than at pre-training (from − 14.7 ± 2.2% to − 12.5 ± 1.7%; P < 0.05). Maximal minute ventilation in both N and H conditions increased after training than in the pre-training period. Conclusions Our IMLET enhanced the respiratory muscle strength, and the decrease in work capacity under hypoxia was reduced regardless of the increase in VO2peak.
Collapse
Affiliation(s)
- Takeshi Ogawa
- 1Division of Art, Music, and Physical Education, Osaka Kyoiku University, Kashiwara, Osaka, Japan
| | - Maiko Nagao
- 1Division of Art, Music, and Physical Education, Osaka Kyoiku University, Kashiwara, Osaka, Japan
| | - Naoto Fujii
- 2Faculty of Health and Sport Sciences in University of Tsukuba, Tsukuba, Japan
| | - Takeshi Nishiyasu
- 2Faculty of Health and Sport Sciences in University of Tsukuba, Tsukuba, Japan
| |
Collapse
|
5
|
Ogawa T, Fujii N, Kurimoto Y, Nishiyasu T. Effect of hypobaria on maximal ventilation, oxygen uptake, and exercise performance during running under hypobaric normoxic conditions. Physiol Rep 2019; 7:e14002. [PMID: 30756526 PMCID: PMC6372535 DOI: 10.14814/phy2.14002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/19/2019] [Accepted: 01/21/2019] [Indexed: 11/24/2022] Open
Abstract
During exposure to high altitude, hypoxia develops because of reductions in barometric pressure and partial pressure of O2 . Although several studies have examined the effects of hypoxia on exercise performance and physiological responses, such as maximal minute ventilation ( V · Emax ) and maximal oxygen uptake ( V · O2max ), how barometric pressure reduction (hypobaria) modulates them remains largely unknown. In this study, 11 young men performed incremental treadmill running tests to exhaustion under three conditions chosen at random: normobaric normoxia (NN; 763 ± 5 mmHg of barometric pressure, equivalent to sea level), hypobaric hypoxia (HH; 492 ± 1 mmHg of barometric pressure, equivalent to 3500 m above sea level (m a.s.l.)), and hypobaric normoxia (HN; 492 ± 1 mmHg of barometric pressure while breathing 32.2 ± 0.1% O2 to match the inspiratory O2 content under NN). V · Emax was higher in HN than in NN (160.9 ± 10.7 vs. 150.7 ± 10.0 L min-1 , P < 0.05). However, no differences in V · O2max and arterial oxyhemoglobin saturation were observed between NN and HN (all P > 0.05). Time to exhaustion was longer in HN than in NN (932 ± 83 vs. 910 ± 79 s, P < 0.05). These results suggest that reduced air density during exposure to an altitude of 3500 m a.s.l. increases maximal ventilation and extends time to exhaustion without affecting oxygen consumption or arterial oxygen saturation.
Collapse
Affiliation(s)
- Takeshi Ogawa
- Department of Physical EducationOsaka Kyoiku UniversityKashiwaraOsakaJapan
| | - Naoto Fujii
- Faculty of Health and Sports ScienceUniversity of TsukubaTsukubaJapan
| | - Yasuhiro Kurimoto
- Faculty of Health and Sports ScienceUniversity of TsukubaTsukubaJapan
| | - Takeshi Nishiyasu
- Faculty of Health and Sports ScienceUniversity of TsukubaTsukubaJapan
| |
Collapse
|
6
|
Acute respiratory muscle unloading by normoxic helium-O₂ breathing reduces the O₂ cost of cycling and perceived exertion in obese adolescents. Eur J Appl Physiol 2014; 115:99-109. [PMID: 25213005 DOI: 10.1007/s00421-014-2993-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 08/28/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE In obesity, an increased work of breathing contributes to a higher O2 cost of exercise and negatively affects exercise tolerance. The purpose of the study was to determine whether, in obese adolescents, acute respiratory muscle unloading via normoxic helium-O2 breathing reduces the O2 cost of cycling and perceived exertion. METHODS Nine males [age 16.8 ± 1.6 (x ± SD) years, body mass 109.9 ± 15.0 kg] performed on a cycle ergometer, breathing room air (AIR) or a 21 % O2-79 % helium mixture (He-O2): an incremental exercise, for determination of [Formula: see text]O2 peak and gas exchange threshold (GET); 12 min constant work rate (CWR) exercises at 70 % of GET (<GET) and 120 % of GET (>GET) determined in AIR. RESULTS [Formula: see text]O2 peak was not different in the two conditions. From the 3rd to the 12th minute of exercise (both during CWR < GET and CWR > GET), [Formula: see text]O2 was lower in He-O2 vs. AIR (end-exercise values: 1.40 ± 0.14 vs. 1.57 ± 0.22 L min(-1) <GET, and 2.23 ± 0.31 vs. 2.54 ± 0.27 L min(-1) >GET). During CWR > GET in AIR, [Formula: see text]O2 linearly increased from the 3rd to the 12th minute of exercise, whereas no substantial increase was observed in He-O2. The O2 cost of cycling was ~10 % (<GET) and ~15 % (>GET) lower in He-O2 vs. AIR. Heart rate and ratings of perceived exertion for dyspnea/respiratory discomfort and leg effort were lower in He-O2. CONCLUSIONS In obese adolescents, acute respiratory muscle unloading via He-O2 breathing lowered the O2 cost of cycling and perceived exertion during submaximal moderate- and heavy-intensity exercise.
Collapse
|
7
|
Ferretti G. Maximal oxygen consumption in healthy humans: theories and facts. Eur J Appl Physiol 2014; 114:2007-36. [PMID: 24986693 DOI: 10.1007/s00421-014-2911-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 05/12/2014] [Indexed: 12/17/2022]
Abstract
This article reviews the concept of maximal oxygen consumption ([Formula: see text]) from the perspective of multifactorial models of [Formula: see text] limitation. First, I discuss procedural aspects of [Formula: see text] measurement: the implications of ramp protocols are analysed within the theoretical work of Morton. Then I analyse the descriptive physiology of [Formula: see text], evidencing the path that led to the view of monofactorial cardiovascular or muscular [Formula: see text] limitation. Multifactorial models, generated by the theoretical work of di Prampero and Wagner around the oxygen conductance equation, represented a radical change of perspective. These models are presented in detail and criticized with respect to the ensuing experimental work. A synthesis between them is proposed, demonstrating how much these models coincide and converge on the same conclusions. Finally, I discuss the cases of hypoxia and bed rest, the former as an example of the pervasive effects of the shape of the oxygen equilibrium curve, the latter as a neat example of adaptive changes concerning the entire respiratory system. The conclusion is that the concept of cardiovascular [Formula: see text] limitation is reinforced by multifactorial models, since cardiovascular oxygen transport provides most of the [Formula: see text] limitation, at least in normoxia. However, the same models show that the role of peripheral resistances is significant and cannot be neglected. The role of peripheral factors is greater the smaller is the active muscle mass. In hypoxia, the intervention of lung resistances as limiting factors restricts the role played by cardiovascular and peripheral factors.
Collapse
Affiliation(s)
- Guido Ferretti
- Département des Neurosciences Fondamentales, Université de Genève, 1 Rue Michel Servet, 1211, Geneva 4, Switzerland,
| |
Collapse
|
8
|
Moga AM, de Marchie M, Saey D, Spahija J. Mechanisms of non-pharmacologic adjunct therapies used during exercise in COPD. Respir Med 2012; 106:614-26. [PMID: 22341681 DOI: 10.1016/j.rmed.2012.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 01/04/2012] [Accepted: 01/12/2012] [Indexed: 11/16/2022]
Abstract
Individuals with chronic obstructive pulmonary disease (COPD) are often limited in their ability to perform exercise due to a heightened sense of dyspnea and/or the occurrence of leg fatigue associated with a reduced ventilatory capacity and peripheral skeletal muscle dysfunction, respectively. Pulmonary rehabilitation programs have been shown to improve exercise tolerance and health related quality of life. Additional therapeutic approaches such as non-invasive ventilatory support (NIVS), heliox (He-O(2)) and supplemental oxygen have been used as non-pharmacologic adjuncts to exercise to enhance the ability of patients with COPD to exercise at a higher exercise-intensity and thus improve the physiological benefits of exercise. The purpose of the current review is to examine the pathophysiology of exercise limitation in COPD and to explore the physiological mechanisms underlying the effect of the adjunct therapies on exercise in patients with COPD. This review indicates that strategies that aim to unload the respiratory muscles and enhance oxygen saturation during exercise alleviate exercise limiting factors and improve exercise performance in patients with COPD. However, available data shows significant variability in the effectiveness across patients. Further research is needed to identify the most appropriate candidates for these forms of therapies.
Collapse
Affiliation(s)
- A M Moga
- School of Physical and Occupational Therapy, McGill University, 3654 Promenade Sir William Osler, Montreal, Quebec H3G 1Y5, Canada
| | | | | | | |
Collapse
|
9
|
Ball JAS, Rhodes A, Grounds RM. A review of the use of helium in the treatment of acute respiratory failure. ACTA ACUST UNITED AC 2011. [DOI: 10.3109/tcic.12.3.105.113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
10
|
Ari A, Harwood R, Sheard M, Dailey P, Fink JB. In vitro comparison of heliox and oxygen in aerosol delivery using pediatric high flow nasal cannula. Pediatr Pulmonol 2011; 46:795-801. [PMID: 21438178 DOI: 10.1002/ppul.21421] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 09/24/2010] [Accepted: 09/25/2010] [Indexed: 11/12/2022]
Abstract
Drug administration via high flow nasal cannula (HFNC) has been described in pediatrics but the amount of albuterol delivery with an HFNC is not known. The purpose of this study is to quantify aerosol delivery with heliox and oxygen (O(2)) in a model of pediatric ventilation. A vibrating mesh nebulizer (Aeroneb Solo, Aerogen) was placed on the inspiratory inlet of a heated humidifier and heated wire circuit attached to a pediatric nasal cannula (Optiflow, Fisher & Paykel). Breathing parameters were tidal volume (V(t)) 100 ml, respiratory rate (RR) 20/min, and I-time of 1 sec. Albuterol sulfate (2.5 mg/3 ml) was administered through a pediatric HFNC with O(2) (100%) and heliox (80/20% mixture). A total of 12 runs, using O(2) and heliox were conducted at 3 and 6 L/min (n = 3). Drug was collected on an absolute filter, eluted and measured using spectrophotometry. The percent inhaled dose (mean ± SD) was similar with heliox and O(2) at 3 L/min (11.41 ± 1.54 and 10.65 ± 0.51, respectively; P = 0.465). However at 6 L/min drug deposition was ≥ 2-fold greater with heliox (5.42 ± 0.54) than O(2) (1.95 ± 0.50; P = 0.01). Using a pediatric model of HFNC, reducing delivered flow from 6 to 3 L/min increased inhaled albuterol delivery ≥ 2-fold but eliminated the increase in inhaled drug efficiency associated with heliox.
Collapse
Affiliation(s)
- Arzu Ari
- Georgia State University, Division of Respiratory Therapy, Atlanta, Georgia 30302-4019, USA.
| | | | | | | | | |
Collapse
|
11
|
Cheung SS, Petersen SR, McLellan TM. Physiological strain and countermeasures with firefighting. Scand J Med Sci Sports 2010; 20 Suppl 3:103-16. [DOI: 10.1111/j.1600-0838.2010.01215.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
12
|
Ogawa T, Calbet JAL, Honda Y, Fujii N, Nishiyasu T. The effects of breathing a helium-oxygen gas mixture on maximal pulmonary ventilation and maximal oxygen consumption during exercise in acute moderate hypobaric hypoxia. Eur J Appl Physiol 2010; 110:853-61. [PMID: 20623231 DOI: 10.1007/s00421-010-1570-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2010] [Indexed: 11/29/2022]
Abstract
To test the hypothesis that maximal exercise pulmonary ventilation (VE max) is a limiting factor affecting maximal oxygen uptake (VO2 max) in moderate hypobaric hypoxia (H), we examined the effect of breathing a helium-oxygen gas mixture (He-O(2); 20.9% O(2)), which would reduce air density and would be expected to increase VE max. Fourteen healthy young male subjects performed incremental treadmill running tests to exhaustion in normobaric normoxia (N; sea level) and in H (atmospheric pressure equivalent to 2,500 m above sea level). These exercise tests were carried out under three conditions [H with He-O(2), H with normal air and N] in random order. VO2 max and arterial oxy-hemoglobin saturation (SaO(2)) were, respectively, 15.2, 7.5 and 4.0% higher (all p < 0.05) with He-O(2) than with normal air (VE max, 171.9 ± 16.1 vs. 150.1 ± 16.9 L/min; VO2 max, 52.50 ± 9.13 vs. 48.72 ± 5.35 mL/kg/min; arterial oxyhemoglobin saturation (SaO(2)), 79 ± 3 vs. 76 ± 3%). There was a linear relationship between the increment in VE max and the increment in VO2 max in H (r = 0.77; p < 0.05). When subjects were divided into two groups based on their VO2 max, both groups showed increased VE max and SaO(2) in H with He-O(2), but VO2 max was increased only in the high VO2 max group. These findings suggest that in acute moderate hypobaric hypoxia, air-flow resistance can be a limiting factor affecting VE max; consequently, VO2 max is limited in part by VE max especially in subjects with high VO2 max.
Collapse
Affiliation(s)
- Takeshi Ogawa
- Institute of Health and Sports Science, University of Tsukuba, Tsukuba, Ibaraki, 305-8574, Japan
| | | | | | | | | |
Collapse
|
13
|
Ferretti G, Bringard A, Perini R. An analysis of performance in human locomotion. Eur J Appl Physiol 2010; 111:391-401. [PMID: 20437056 DOI: 10.1007/s00421-010-1482-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2010] [Indexed: 10/19/2022]
Abstract
This paper reports an analysis of the principles underlying human performances on the basis of the work initiated by Pietro Enrico di Prampero. Starting from the concept that the maximal speed that can be attained over a given distance with a given locomotion mode is directly proportional to the maximal sustainable power and inversely proportional to the energy cost of locomotion, we discuss the maximal powers (and capacities) of anaerobic (lactic and alactic) and aerobic metabolisms and the factors that limit them, and the factors affecting the energy cost of various locomotion modes. Special attention is given to the role of air resistance and frictional forces. Finally, computation of performance speed is discussed along the approach originally developed by di Prampero.
Collapse
Affiliation(s)
- Guido Ferretti
- Département des Neurosciences Fondamentales, Centre Médical Universitaire, Université de Genève, Rue Michel Servet 1, 1211, Geneve 4, Switzerland.
| | | | | |
Collapse
|
14
|
Effect of respiratory muscle training on maximum aerobic power in normoxia and hypoxia. Respir Physiol Neurobiol 2010; 170:268-72. [DOI: 10.1016/j.resp.2010.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 02/05/2010] [Accepted: 02/08/2010] [Indexed: 11/18/2022]
|
15
|
Cross TJ, Sabapathy S, Schneider DA, Haseler LJ. Breathing He-O2attenuates the slow component of O2uptake kinetics during exercise performed above the respiratory compensation threshold. Exp Physiol 2009; 95:172-83. [DOI: 10.1113/expphysiol.2009.048975] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
16
|
Calbet JAL, Lundby C. Air to Muscle O2Delivery during Exercise at Altitude. High Alt Med Biol 2009; 10:123-34. [DOI: 10.1089/ham.2008.1099] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- José A. L. Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Spain
- Copenhagen Muscle Research Centre, Copenhagen, Denmark
| | - Carsten Lundby
- Copenhagen Muscle Research Centre, Copenhagen, Denmark
- Department of Sport Science, University of Århus, Århus, Denmark
| |
Collapse
|
17
|
Kim IK, Corcoran T. Recent Developments in Heliox Therapy for Asthma and Bronchiolitis. CLINICAL PEDIATRIC EMERGENCY MEDICINE 2009. [DOI: 10.1016/j.cpem.2009.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
18
|
O'Callaghan C, White J, Jackson J, Crosby D, Dougill B, Bland H. The effects of Heliox on the output and particle-size distribution of salbutamol using jet and vibrating mesh nebulizers. ACTA ACUST UNITED AC 2008; 20:434-44. [PMID: 18158716 DOI: 10.1089/jam.2007.0614] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
There are theoretical benefits of delivering drug aerosols to patients with asthma and chronic obstructive pulmonary disease (COPD) using Heliox as a carrier gas. The objective of this study was to develop systems to allow bronchodilators nebulized by a breath enhanced jet nebulizer and a vibrating mesh nebulizer to be delivered to patients in Heliox. This was achieved by attaching a reservoir to the nebulizers to ensure inhaled Heliox was not diluted by entrained air. For the vibrating mesh nebulizer, the total output was significantly higher after 5 min of nebulization when Heliox rather than air was used as the delivery gas (p < 0.001). The proportion of drug in particles <5 microm was 58.1% for Heliox and 50.1% when air was entrained. When the breath enhanced nebulizer was used a much higher driving flow of Heliox, compared to air, was required to deliver a similar dose of drug (p < 0.05). The total amount of drug likely to be inhaled was significantly higher when the vibrating mesh nebulizer (Aerogen) was used compared to the breath enhanced jet nebulizer (Pari LC plus) (p < 0.001). The amount of drug likely to be inhaled was also significantly greater for the adult as opposed to pediatric breathing pattern for all nebulizers and flows tested with the exception of the Aeroneb and Heliox entrainment. In this case, total amounts were similar for both patterns but for the pediatric pattern, the time taken to reach this output was longer. Such information is required to allow appropriate interpretation of clinical trials of drug delivery using Heliox.
Collapse
Affiliation(s)
- Christopher O'Callaghan
- Department of Infection, Immunity and Inflammation, Division of Child Health, University of Leicester, Leicester Royal Infirmary, Leicester, United Kingdom.
| | | | | | | | | | | |
Collapse
|
19
|
Ansley L, Petersen D, Thomas A, St Clair Gibson A, Robson-Ansley P, Noakes TD. The effect of breathing an ambient low-density, hyperoxic gas on the perceived effort of breathing and maximal performance of exercise in well-trained athletes. Br J Sports Med 2007; 41:2-7. [PMID: 17062658 PMCID: PMC2465133 DOI: 10.1136/bjsm.2006.026989] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2006] [Indexed: 11/03/2022]
Abstract
BACKGROUND The role of the perception of breathing effort in the regulation of performance of maximal exercise remains unclear. AIMS To determine whether the perceived effort of ventilation is altered through substituting a less dense gas for normal ambient air and whether this substitution affects performance of maximal incremental exercise in trained athletes. METHODS Eight highly trained cyclists (mean SD) maximal oxygen consumption (VO(2)max) = 69.9 (7.9) (mlO(2)/kg/min) performed two randomised maximal tests in a hyperbaric chamber breathing ambient air composed of either 35% O(2)/65% N(2) (nitrox) or 35% O(2)/65% He (heliox). A ramp protocol was used in which power output was incremented at 0.5 W/s. The trials were separated by at least 48 h. The perceived effort of breathing was obtained via Borg Category Ratio Scales at 3-min intervals and at fatigue. Oxygen consumption (VO(2)) and minute ventilation (V(E)) were monitored continuously. RESULTS Breathing heliox did not change the sensation of dyspnoea: there were no differences between trials for the Borg scales at any time point. Exercise performance was not different between the nitrox and heliox trials (peak power output = 451 (58) and 453 (56) W), nor was VO(2)max (4.96 (0.61) and 4.88 (0.65) l/min) or maximal V(E) (157 (24) and 163 (22) l/min). Between-trial variability in peak power output was less than either VO(2)max or maximal V(E). CONCLUSION Breathing a less dense gas does not improve maximal performance of exercise or reduce the perception of breathing effort in highly trained athletes, although an attenuated submaximal tidal volume and V(E) with a concomitant reduction in VO(2) suggests an improved gas exchange and reduced O(2) cost of ventilation when breathing heliox.
Collapse
Affiliation(s)
- L Ansley
- School of Life Sciences, Kingston University, Penrhyn Road, Kingston-upon-Thames, Surrey KT1 2EE, UK.
| | | | | | | | | | | |
Collapse
|
20
|
Eves ND, Petersen SR, Haykowsky MJ, Wong EY, Jones RL. Helium-Hyperoxia, Exercise, and Respiratory Mechanics in Chronic Obstructive Pulmonary Disease. Am J Respir Crit Care Med 2006; 174:763-71. [PMID: 16840742 DOI: 10.1164/rccm.200509-1533oc] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Hyperoxia and normoxic helium independently reduce dynamic hyperinflation and improve the exercise tolerance of patients with chronic obstructive pulmonary disease (COPD). Combining these gases could have an additive effect on dynamic hyperinflation and a greater impact on respiratory mechanics and exercise tolerance. OBJECTIVE To investigate whether helium-hyperoxia improves the exercise tolerance and respiratory mechanics of patients with COPD. METHODS Ten males with COPD (FEV(1) = 47 +/- 17%pred [mean +/- SD]) performed randomized constant-load cycling at 60% of maximal work rate breathing air, hyperoxia (40% O(2), 60% N(2)), normoxic helium (21% O(2), 79% He), or helium-hyperoxia (40% O(2), 60% He). MEASUREMENTS Exercise time, inspiratory capacity (IC), work of breathing, and exertional symptoms were measured with each gas. RESULTS Compared with air (9.4 +/- 5.2 min), exercise time was increased with hyperoxia (17.8 +/- 5.8 min) and normoxic helium (16.7 +/- 9.1 min) but the improvement with helium-hyperoxia (26.3 +/- 10.6 min) was greater than both these gases (p = 0.019 and p = 0.007, respectively). At an isotime during exercise, all three gases reduced dyspnea and both helium mixtures increased IC and tidal volume. Only helium-hyperoxia significantly reduced the resistive work of breathing (15.8 +/- 4.2 vs. 10.1 +/- 4.1 L . cm H(2)O(-1)) and the work to overcome intrinsic positive end-expiratory pressure (7.7 +/- 1.9 vs. 3.6 +/- 2.1 L . cm H(2)O(-1)). At symptom limitation, tidal volume remained augmented with both helium mixtures, but IC and the work of breathing were unchanged compared with air. CONCLUSION Combining helium and hyperoxia delays dynamic hyperinflation and improves respiratory mechanics, which translates into added improvements in exercise tolerance for patients with COPD.
Collapse
Affiliation(s)
- Neil D Eves
- Rehabilitation Medicine, University of Calgary, Calgary, AB, Canada T2N 1N4.
| | | | | | | | | |
Collapse
|
21
|
Corcoran TE, Gamard S. Development of Aerosol Drug Delivery with Helium Oxygen Gas Mixtures. ACTA ACUST UNITED AC 2004; 17:299-309. [PMID: 15684730 DOI: 10.1089/jam.2004.17.299] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Aerosol drug delivery using helium-oxygen gas mixtures (heliox) is considered in terms of flow physics, atomization, and aerosol mechanics. Theoretical considerations are then related to past studies of the physiological effects of the inhalation of heliox and its potential use as a drug delivery medium. Past clinical trials of heliox investigating this use are reviewed and technical recommendations made for its successful development. It is proposed that improved peripheral lung drug delivery with heliox is highly dependent on proper administration, especially the inclusion of proper reservoir system for the gas.
Collapse
Affiliation(s)
- T E Corcoran
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
| | | |
Collapse
|
22
|
Eves ND, Petersen SR, Jones RL. Effects of helium and 40% O2 on graded exercise with self-contained breathing apparatus. ACTA ACUST UNITED AC 2004; 28:910-26. [PMID: 14992128 DOI: 10.1139/h03-065] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Maximal exercise performance is decreased when breathing from a self-contained breathing apparatus (SCBA), owing to a ventilatory limitation imposed by the increased expiratory resistance. To test the hypothesis that decreasing the density of the breathing gas would improve maximal exercise performance, we studied 15 men during four graded exercise tests with the SCBA. Participants breathed a different gas mixture during each test: normoxia (NOX; 21% O2, 79% N2), hyperoxia (HOX; 40% O2, 60% N2), normoxic helium (HE-OX; 21% O2, 79% He), and hyperoxic helium (HE-HOX; 40% O2, 60% He). Compared to NOX, power output at the ventilatory threshold and at maximal exercise significantly increased with both hyperoxic mixtures. Minute ventilation was increased at peak exercise with both helium mixtures, and maximal aerobic power (VO2max) was significantly increased by 12.9 +/- 5.6%, 10.2 +/- 6.3%, and 21.8 +/- 5.6% with HOX, HE-OX, and HE-HOX, respectively. At peak exercise, the expired breathing resistance imposed by the SCBA was significantly decreased with both helium mixtures, and perceived respiratory distress was lower with HE-HOX. The results show that HE-OX improved maximal exercise performance by minimizing the ventilation limitation. The performance-enhancing effect of HOX may be explained by increased arterial oxygen content. Moreover, HE-HOX appeared to combine the effects of helium and hyperoxia on VO2max.
Collapse
Affiliation(s)
- Neil D Eves
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB, T6G 2H9
| | | | | |
Collapse
|
23
|
Babb TG, DeLorey DS, Wyrick BL. Ventilatory response to exercise in aged runners breathing He-O2 or inspired CO2. J Appl Physiol (1985) 2003; 94:685-93. [PMID: 12531912 DOI: 10.1152/japplphysiol.00214.2002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ventilatory response to exercise below ventilatory threshold (VTh) increases with aging, whereas above VTh the ventilatory response declines only slightly. We wondered whether this same ventilatory response would be observed in older runners. We also wondered whether their ventilatory response to exercise while breathing He-O(2) or inspired CO(2) would be different. To investigate, we studied 12 seniors (63 +/- 4 yr; 10 men, 2 women) who exercised regularly (5 +/- 1 days/wk, 29 +/- 11 mi/wk, 16 +/- 6 yr). Each subject performed graded cycle ergometry to exhaustion on 3 separate days, breathing either room air, 3% inspired CO(2), or a heliox mixture (79% He and 21% O(2)). The ventilatory response to exercise below VTh was 0.35 +/- 0.06 l x min(-1) x W(-1) and above VTh was 0.66 +/- 0.10 l x min(-1) x W(-1). He-O(2) breathing increased (P < 0.05) the ventilatory response to exercise both below (0.40 +/- 0.12 l x min(-1) x W(-1)) and above VTh (0.81 +/- 0.10 l x min(-1) x W(-1)). Inspired CO(2) increased (P < 0.001) the ventilatory response to exercise only below VTh (0.44 +/- 0.10 l x min(-1) x W(-1)). The ventilatory responses to exercise with room air, He-O(2), and CO(2) breathing of these fit runners were similar to those observed earlier in older sedentary individuals. These data suggest that the ventilatory response to exercise of these senior runners is adequate to support their greater exercise capacity and that exercise training does not alter the ventilatory response to exercise with He-O(2) or inspired CO(2) breathing.
Collapse
Affiliation(s)
- T G Babb
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas and The University of Texas Southwestern Medical Center, 77231, USA.
| | | | | |
Collapse
|
24
|
Babb TG, DeLorey DS. Hyperventilation with He-O2 breathing is not decreased by superimposed external resistance. Respir Physiol Neurobiol 2002; 133:139-51. [PMID: 12385739 DOI: 10.1016/s1569-9048(02)00165-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to determine the effect of imposed external resistance on the ventilatory response to He-O(2) breathing during peak exercise. To accomplish this purpose, separate inspiratory and expiratory external resistances were applied to offset for the decrease in intrapulmonary airway resistance with He-O(2) breathing. Seven men and three women (69+/-3 years, mean+/-S.D.) with normal pulmonary function performed graded cycle ergometry to exhaustion breathing room air, He-O(2) (79% He, 21% O(2)), He-O(2) with imposed expiratory resistance, and He-O(2) with imposed inspiratory resistance. Ventilation (VE), lung mechanics, and PET(CO(2)) were measured during each 1 min increment in work rate and were analyzed by one-way ANOVA for repeated measures at rest, ventilatory threshold (VTh), and peak exercise. In response, VE was increased and PET(CO(2)) was decreased at VTh (P<0.01) and peak exercise (P<0.01) whenever breathing He-O(2). Thus, VE was increased during exercise above VTh with He-O(2) breathing regardless of increases in inspiratory or expiratory external resistance. In conclusion, these data suggest that inspiratory resistive unloading is no more important than expiratory resistive unloading to the increase in VE with He-O(2) breathing during heavy and peak exercise.
Collapse
Affiliation(s)
- T G Babb
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas and The University of Texas Southwestern Medical Center, 7232 Greenville Avenue, Dallas, TX 77231, USA.
| | | |
Collapse
|
25
|
Babb TG. Breathing He-O2 increases ventilation but does not decrease the work of breathing during exercise. Am J Respir Crit Care Med 2001; 163:1128-34. [PMID: 11316648 DOI: 10.1164/ajrccm.163.5.9908025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We previously observed an increase in minute ventilation (V E) with resistive unloading (He-O2 breathing) in healthy elderly subjects with normal pulmonary function. To investigate the effects of resistive unloading in elderly subjects with mild chronic airflow limitation (FEV(1)/FVC: 61 +/- 4%), we studied 10 elderly men and women 70 +/- 3 yr of age. These subjects performed graded cycle ergometry to exhaustion, once breathing room air and once breathing a He-O2 gas mixture (79% He, 21% O2). V E, pulmonary mechanics, and PET(CO2) were measured during each 1-min increment in work rate. Data were analyzed by paired t test at rest, at ventilatory threshold (VTh), and during maximal exercise. V E was significantly (p < 0.05) increased at VTh (3.4 +/- 4.0 L/min or 12 +/- 15% increase) and maximal exercise (15.2 +/- 9.7 L/min or 22 +/- 13% increase) while breathing He-O2. Concomitant to the increase in V E, PET(CO2) was decreased at all levels (p < 0.01), whereas total work of breathing against the lung was not different. We concluded that V E is increased during He-O2 breathing because of resistive unloading of the airways and the maintenance of the relationship between the work of breathing and exercise work rate.
Collapse
Affiliation(s)
- T G Babb
- Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, and University of Texas Southwestern Medical Center, Dallas, Texas, USA.
| |
Collapse
|