https://en.wikipedia.org/wiki/Warburg_hypothesis 

https://stm.sciencemag.org/content/7/277/277ra30

STEPHEN M. HATFIELD, J. K. (2015). Immunological mechanisms of the antitumor effects of supplemental oxygenation. SCIENCE TRANSLATIONAL MEDICINE, 7(277), 1-12. doi:https://doi.org/10.1126/scitranslmed.aaa1260

Abstract

Tumors are generally accompanied by immune cells and express unique antigens. However, immune surveillance isn't perfect, and tumor growth may not be inhibited. Furthermore, tumors are frequently hypoxic, as their fast development outpaces their blood and oxygen supply. Hatfield et.al proposed the association of these two phenomena by showing that T cells get away from the hypoxic regions of tumors. According to the authors, breathing supplementary oxygen is a solution to overcome this issue and they have demonstrated it in mice with lung tumors. Higher oxygen concentrations throughout the body boosted tumor oxygenation, allowing immune cells to enter the tumors and fight them, increasing the animals' survival time.

https://gem-3910432.nethttps://pubmed.ncbi.nlm.nih.gov/6711017/

von Ardenne, M., Klemm, W., & Klinger, J. (1984). Doppelblindstudie zur starken anhaltenden Steigerung der körperlichen Leistungsfähigkeit nach Sauerstoff-Mehrschritt-Therapie-Behandlungen [Double-blind study on the long-lasting improvement of physical endurance following oxygen-multistep-therapy]. Zeitschrift fur Alternsforschung, 39(1), 17–30.

Abstract

The characteristic of Oxygen Multistep Therapy is the long-lasting improvement of the energetic or oxygenation state of the organism. This specific effect is confirmed with statistical significance by a two-centric double-blind study on 20 male healthy volunteers from the working population. In this study the ergometrically measurable increase of physical fitness, which was determined two weeks after performance of two 15 min-oxygen-multistep-quick processes, served as over-all criterion. The mean value of the continuing elevation was 17%. On individuals having initially lower physical capacities and therefore being particularly in need of treatment, increases of 25, 33, and even 45% were determined.

Exercise and immunity. (n.d.). Retrieved from MedlinePlus: 

https://medlineplus.gov/ency/article/007165.htm

Computer-assisted measurements of information processing capacity, intelligence, short-term memory and further parameters of cerebral performance.

von Ardenne, M., & Klemm, W. (1989). Steigerung der geistigen Leistungsfähigkeit durch Sauerstoff-Mehrschritt-Therapie. Computergestützte Messungen der Informationsverarbeitungs-Kapazität, der Intelligenz, des Kurzzeitgedächtnisses und weiterer Grössen zerebraler Leistungsfähigkeit [Increasing mental performance by multistep oxygen therapy. Computer-assisted measurements of information processing capacity, intelligence, short-term memory and further parameters of cerebral performance]. Zeitschrift fur Alternsforschung, 44(1), 37–48.

https://pubmed.ncbi.nlm.nih.gov/2711706/

Abstract

Several basic characteristics of mental capacity were measured on 59 patients by means of computer-based-methods before and after oxygen multistep therapy (O2-MT) and compared with the results obtained from 14 volunteers serving as controls. Before and without O2-MT, an appreciable, age-dependent decline of the short-term memory capacity (general fluid intelligence) was found. O2-MT, completed by brain jogging, effected a significant increase in the presence duration by 0.4-0.7 secs, in the information flow by 1.4-1.9 bit/sec, resulting in an increase in the short-term memory capacity by 19-23% (in two experimental groups). The short-term memory itself was, however, not improved as compared to the controls. Moreover, the times needed for the accomplishment of perception, interference and reaction tests became significantly shorter by 12-18%. By using the screening test for cerebral insufficiency (CI), which is based on these parameters, the suspicion of CI could be excluded in 18 of 59 patients.

https://pubmed.ncbi.nlm.nih.gov/17021333/

Padmanabhan, P., & McCullough, A. R. (2007). Penile oxygen saturation in the flaccid and erect penis in men with and without erectile dysfunction. Journal of andrology, 28(2), 223–228. https://doi.org/10.2164/jandrol.106.001313

Abstract

It is believed that a chronic state of corporal oxygen desaturation or hypoxemia secondary to the loss of nocturnal erections is a fundamental pathophysiological cause of erectile dysfunction (ED). Limited invasive blood gas measurements in human models have shown decreased oxygen tension in vasculogenic impotence. Normative data on flaccid and erect oxygen saturation (StO(2)) levels are lacking due to the invasive nature of blood gas determinations. Our objective was to determine StO(2) in the flaccid and erect penis in men with and without ED using a tissue oximeter. This FDA-approved instrument provides instantaneous, noninvasive, painless local tissue StO(2) measurements, which highly correlate to blood gas data. The study population included 171 men (18-90 years) who presented to one andrologist. They completed the Sexual Health Inventory for Men (SHIM) based on pharmacologically unassisted erectile function and had penile StO(2) measurements taken. 64 of these men had repeat measurements after PGE-1 induced erections. There are significant differences (P<.001) in corporal and glanular StO(2) in the flaccid (right corpora, 45.23%; left corpora, 52.50%) and erect state (right corpora, 76.58; left corpora, 80.42). Men with ED (right corpora, 45.04% vs 53.58%; P=.02; and left corpora, 50.95% vs 58.78%; P=.03) have significantly lower corporal penile StO(2). Future prospective data collection can correlate penile StO(2) in specific populations, such as diabetics and RRP patients. This may help further elucidate the relationship between corporal hypoxia and the development and progression of ED and possibly its treatment and prevention.

https://pubmed.ncbi.nlm.nih.gov/6475110/

von Ardenne M. (1984). Die Abhängigkeit des Sauerstofftransportes in das Körpergewebe vom Lebensalter und die günstige Beeinflussung dieses Transportes durch Sauerstoff-Mehrschritt-Therapie [Age-dependence of oxygen transport into body tissues and the favorable modification of this transport by multistep oxygen therapy]. Zeitschrift fur Alternsforschung, 39(4), 187–210.

Abstract

The routine determination of the oxygen flux into body's tissues (= resting oxygen uptake) should gain more attention in practice, because its magnitude can be considered a kind of characteristic value for the energetic state of the entire organism. The determination of this value has deserved special interest since we discovered a "switch mechanism" of blood microcirculation, which depends on the oxygen state of the body. A high value of pO2 (greater than or equal to 50 mm of Hg) at the venous ends of the capillaries, attainable by the procedures of the Oxygen Multistep Therapy and by powerful physical exercise as well, results in an increase of the blood microcirculation and, consequently, in a permanent elevation of the oxygen influx and uptake, respectively. This effect can persist for weeks, months or even years. If the oxygen state gets worse and declines below a certain threshold, e. g. in progressing age or after long-term distress, the cross sections of the capillaries shrink by swelling of the endothelial cells, and the blood microcirculation is diminished for an extended period of time. The utilization of the above-mentioned switch mechanism for permanent improvement of the oxygen flux into all the tissues of the organism is therefore of decisive importance for fighting against the common cause of many diseases, disorders and complaints going often along with increasing age due to insufficient oxygen (energy) supply for general metabolism. As can be taken from measurements described in this paper, the main contribution to this deterioration comes from the age-dependent diminution of the cardiac minute or stroke volume, respectively, since eta--the percent exhaustion of the oxygen-binding capacity of blood--increases even with progressing age, as was found by us. Numerous determinations of the arterial and venous pO2 resting levels have shown that the values of eta can almost be doubled easily by the procedures of the Oxygen Multistep Therapy, whereby--as a rule--the age-dependent decrease of the cardiac output is overcompensated. Within the schedule of the Oxygen Multistep Therapy, the third step prescribes a temporary enhancement of the blood circulation by physical exercise. With respect to this measure, there was progress of principal importance by the idea to increase the minute volume by application of sympathicomimetics during the single treatment units under moderately enhanced oxygen inhalation, but with due consideration of the known contraindications.

https://health.ucsd.edu/news/releases/Pages/2014-06-05-connection-between-oxygen-and-diabetes.aspx

A lack of O2 in fat cells triggers inflammation and insulin resistance in obesity.

https://pubmed.ncbi.nlm.nih.gov/3705655/

von Ardenne M. (1986). Steuerung und Nutzung eines Kapillarwand-Schaltmechanismus der Blutmikrozirkulation. Neuere Ergebnisse der Sauerstoff-Mehrschritt-Therapie-Forschung [Control and usefulness of a capillary-wall switch mechanism in blood microcirculation. Recent results of oxygen multistep therapy research]. Zeitschrift fur die gesamte innere Medizin und ihre Grenzgebiete, 41(4), 85–91.

Abstract

The measurement of the O2 status of the human organism, the knowledge of factors which influence it and the using and development, respectively, of measures for its permanent improvement are of great importance for the prevention diagnosis, prophylaxis and therapy. The O2-intake in rest of the organism is regarded as absolute characteristic of the oxygen status. In investigations of the dynamics of the status it is in most cases sufficient to use the arteriovenous Hb-O2 saturation difference as relative distinctive mark, the representative determination of which from routine measurements of pO2 in rest is discussed. From such measurements the strong dynamics of the O2 status was found. Apart from the deterioration with growing age the deterioration by stressor influences of different kind, in hyposthenias and the minima in the 24-hour-cycle were established. Improvements were measured after perseverance training and after treatments with processes of the oxygen multistep therapy. After discussion of the three basic steps of this therapy the 36-h-O2-multistep process and the 15-min-O2-multistep rapid process are mentioned as standard variants which are to be used ambulatorily. The rapid process is entered more in detail and the practice of its performance as well as the results of measurements of the typical pO2 in rest before and after these processes are discussed. Surprising is the existence of the increase affected by the arterial pO2 in rest and of the decrease of the venous pO2 in rest for weeks, months up to years.

https://pubmed.ncbi.nlm.nih.gov/1930489/

Wolf, O., & Hanson, J. (1991). Ergebnisse der Sauerstoff-Mehrschritt-Therapie bei der Behandlung des Hörsturzes [Results of multistep oxygen therapy in the treatment of sudden hearing loss]. Laryngo- rhino- otologie, 70(9), 475–478. https://doi.org/10.1055/s-2007-998080

Abstract

Oxygen multistep therapy (von Ardenne) was applied in 28 patients suffering from an idiopathic sudden hearing loss. The oxygen therapy consisted of a multistep short procedure, each of which lasted for 15 minutes. The results of our study were evaluated by means of standardised statistics confirming the effectiveness and even the superiority of the oxygen multistep therapy in comparison with any other treatment, and also in view of the spontaneous remission rate in cases of sudden hearing loss.

https://pubmed.ncbi.nlm.nih.gov/3367808/

von Ardenne M. (1988). Adaptation of anticancer strategies to progress in tumor immunology. Medical hypotheses, 25(3), 163–173. https://doi.org/10.1016/0306-9877(88)90054-0

Abstract

The numerical development of cancer cells during tumor growth and under current forms of therapy is quantitatively described as a fundamental of a scientifically founded anticancer strategy. As to general cancer prevention, suppression of metastasis and reduction of recurrencies, figures are derived, which allow one to assess the minimal number of malignant cells to be killed. The killing potency of current tumor-immunological measures has not so far been sufficient enough to have a good chance of achieving these ambitious goals. The main reason for this is the neglect of the oxygen status of the body and its dynamics. This is a surprising fact, since all immunological mechanisms are known to be energy-, i.e., oxygen-dependent. The experimentally confirmed correlation between the effectiveness of body defense and the quality of the oxygen status was the origin of several variants of the oxygen multistep immunostimulation concept (application of immunostimulators combined with the oxygen multistep therapy). Clinical results reflect the remarkable increase of cell-killing potency achievable by these measures and give reasons for the adaptation of anticancer strategies to progress in tumor immunology. Furthermore, real methodological proposals are made for general cancer prevention, suppression of metastasis, and reduction of recurrences, and the concept of a combined therapy is developed. This therapy comprises the currently accepted measures, such as surgery, irradiation and drugs, and the adjuvant O2 multistep immunostimulation, which is applied threefold according to a particular schedule. The advantage of this combination is that the patient comes first into the enjoyment of all the beneficial effects that established regimens can offer for the particular case. Then and moreover, the patient gains better quality of life, because the adverse side-effects of radiation and drugs are attenuated and, finally, the individual gets a fair chance of stopping the progression of the disease.

https://pubmed.ncbi.nlm.nih.gov/3548643/

von Ardenne M. (1986). Hypothesen: Anpassung der Strategie gegen den Krebs an Fortschritte der Tumorimmunologie. Allgemeine Krebs-Prophylaxe, Metastasierungs-Prophylaxe, Kombination Klassischer Krebstherapie mit O2-Mehrschritt-Immunstimulation [Hypotheses: The adaptation of cancer strategy to progress in tumor immunology. General cancer prevention, metastasis prevention and the combination of classical cancer therapies with O2 multistep immunostimulation]. Archiv fur Geschwulstforschung, 56(6), 457–470.

Abstract

The numerical development of cancer cells during tumor growth and under current forms of therapy is quantitatively described as a fundament of a scientifically founded anticancer strategy. As to general cancer prevention, suppression of metastasis and reduction of recurrencies, figures for orientation are derived, which allow to assess the minimal number of malignant cells to be killed. The killing potency of current tumor immunological measures has been not so far sufficient enough to have a good chance for achieving these pretentious goals. The mean reyason for this to be supposed the neglection of the oxygen status of the body and its dynamics. This is a surprising fact, since all immunological mechanisms are known to be energy-, i.e., oxygen-dependent. The experimentally confirmed correlation between the effectiveness of body defense and the quality of the oxygen status was the origin of several variants of the oxygen multistep immunostimulation concept (application of immunostimulators combined with the oxygen multistep therapy). Clinical results reflect the remarkable increase of the cell-killing potency achievable by these measures and give reasons for the adaptation of anticancer strategies to progress in tumor immunology. Furthermore, real methodological proposals are made for general cancer prevention, suppression of metastasis, and reduction of recurrences, and the concept of a combined therapy is developed. This therapy comprises the currently accepted measures, such as surgery, irradiation and drugs, and the adjuvant O2 multistep immunostimulation, which is applied three-fold according to a specific schedule. The advantage of this combination is that the patient comes first into the enjoyment of all the beneficial effects that established regimens can offer for the particular case. Then and moreover, the patient gains better quality of life, because the adverse side-effects of radiation and drugs are attenuated and, finally, the individual gets a fair chance of stopping the progression of the disease.

https://www.webmd.com/lung/copd/oxygen-therapy-for-copd

https://pubmed.ncbi.nlm.nih.gov/25785586/

Nishi, S. P., Zhang, W., Kuo, Y. F., & Sharma, G. (2015). Oxygen therapy use in older adults with chronic obstructive pulmonary disease. PloS one, 10(3), e0120684. https://doi.org/10.1371/journal.pone.0120684

Abstract

Rationale: Oxygen therapy improves survival and function in severely hypoxemic chronic obstructive pulmonary disease (COPD) patients based on two landmark studies conducted over 40 years ago. We hypothesize that oxygen users in the current era may be very different. We examined trends and subject characteristics associated with oxygen therapy use from 2001-2010 in the United States.

Conclusions: Any oxygen use among fee-for service Medicare beneficiaries with COPD is high. Current users of oxygen are older females with multiple comorbidities. Decline in sustained oxygen therapy use after 2008 may be related to reimbursement policy change.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5536739/

Zhang, J., Lin, L., Pan, K., Zhou, J., & Huang, X. (2016). High-flow nasal cannula therapy for adult patients. The Journal of international medical research, 44(6), 1200–1211. https://doi.org/10.1177/0300060516664621

Abstract

High-flow nasal cannula (HFNC) oxygen therapy has several physiological advantages over traditional oxygen therapy devices, including decreased nasopharyngeal resistance, washing out of the nasopharyngeal dead space, generation of positive pressure in the pharynx, increasing alveolar recruitment in the lungs, humidification of the airways, increased fraction of inspired oxygen and improved mucociliary clearance. Recently, the use of HFNC in treating adult critical illness patients has significantly increased, and it is now being used in many patients with a range of different disease conditions. However, there are no established guidelines to direct the safe and effective use of HFNC for these patients. This review article summarizes the available published literature on the positive physiological effects, mechanisms of action, and the clinical applications of HFNC, compared with traditional oxygen therapy devices. The available literature suggests that HFNC oxygen therapy is an effective modality for the early treatment of critically adult patients.

https://pubmed.ncbi.nlm.nih.gov/29115912/

Cardinale, D. A., & Ekblom, B. (2018). Hyperoxia for performance and training. Journal of sports sciences, 36(13), 1515–1522. https://doi.org/10.1080/02640414.2017.1398893

Abstract

Recent technological developments have made it possible to use hyperoxia as an enhancement aid during training. Athletes wearing a mask can breathe a higher fraction of oxygen from a stationary or portable apparatus while exercising. A large body of evidence indicates that the oxygen transport capacity, lactate metabolism, power output and work tolerance (endurance) are improved when breathing hyperoxia. The physiological mechanisms underlying these performance improvements, although still not fully elucidated, are based on higher oxygen delivery and reduced central fatigue. Although much is known about the acute effects of hyperoxia, the effect of hyperoxic-supplemented endurance training on performance and the mechanisms beneath training adaptations are not very well understood, especially in well-trained endurance athletes. The few studies on the physiological effects of hyperoxia training have been conducted with conflicting results, discussed in this paper. Potential detrimental effects have not yet been shown experimentally and warrant further investigation.

https://pubmed.ncbi.nlm.nih.gov/29488785/

Brugniaux, J. V., Coombs, G. B., Barak, O. F., Dujic, Z., Sekhon, M. S., & Ainslie, P. N. (2018). Highs and lows of hyperoxia: physiological, performance, and clinical aspects. American journal of physiology. Regulatory, integrative and comparative physiology, 315(1), R1–R27. https://doi.org/10.1152/ajpregu.00165.2017

Abstract

Molecular oxygen (O2) is a vital element in human survival and plays a major role in a diverse range of biological and physiological processes. Although normobaric hyperoxia can increase arterial oxygen content ([Formula: see text]), it also causes vasoconstriction and hence reduces O2 delivery in various vascular beds, including the heart, skeletal muscle, and brain. Thus, a seemingly paradoxical situation exists in which the administration of oxygen may place tissues at increased risk of hypoxic stress. Nevertheless, with various degrees of effectiveness, and not without consequences, supplemental oxygen is used clinically in an attempt to correct tissue hypoxia (e.g., brain ischemia, traumatic brain injury, carbon monoxide poisoning, etc.) and chronic hypoxemia (e.g., severe COPD, etc.) and to help with wound healing, necrosis, or reperfusion injuries (e.g., compromised grafts). Hyperoxia has also been used liberally by athletes in a belief that it offers performance-enhancing benefits; such benefits also extend to hypoxemic patients both at rest and during rehabilitation. This review aims to provide a comprehensive overview of the effects of hyperoxia in humans from the "bench to bedside." The first section will focus on the basic physiological principles of partial pressure of arterial O2, [Formula: see text], and barometric pressure and how these changes lead to variation in regional O2 delivery. This review provides an overview of the evidence for and against the use of hyperoxia as an aid to enhance physical performance. The final section addresses pathophysiological concepts, clinical studies, and implications for therapy. The potential of O2 toxicity and future research directions are also considered.

Computer-assisted measurements of information processing capacity, intelligence, short-term memory and further parameters of cerebral performance

https://pubmed.ncbi.nlm.nih.gov/2711706/

von Ardenne, M., & Klemm, W. (1989). Steigerung der geistigen Leistungsfähigkeit durch Sauerstoff-Mehrschritt-Therapie. Computergestützte Messungen der Informationsverarbeitungs-Kapazität, der Intelligenz, des Kurzzeitgedächtnisses und weiterer Grössen zerebraler Leistungsfähigkeit [Increasing mental performance by multistep oxygen therapy. Computer-assisted measurements of information processing capacity, intelligence, short-term memory and further parameters of cerebral performance]. Zeitschrift fur Alternsforschung, 44(1), 37–48.

Abstract

Several basic characteristics of mental capacity were measured on 59 patients by means of computer-based-methods before and after oxygen multistep therapy (O2-MT) and compared with the results obtained from 14 volunteers serving as controls. Before and without O2-MT, an appreciable, age-dependent decline of the short-term memory capacity (general fluid intelligence) was found. O2-MT, completed by brain jogging, effected a significant increase in the presence duration by 0.4-0.7 secs, in the information flow by 1.4-1.9 bit/sec, resulting in an increase in the short-term memory capacity by 19-23% (in two experimental groups). The short-term memory itself was, however, not improved as compared to the controls. Moreover, the times needed for the accomplishment of perception, interference and reaction tests became significantly shorter by 12-18%. By using the screening test for cerebral insufficiency (CI), which is based on these parameters, the suspicion of CI could be excluded in 18 of 59 patients.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4996887/

Toshiyuki Ohya, Ryo Yamanaka, Hayato Ohnuma, Masahiro Hagiwara, Yasuhiro Suzuki

Sports Med Open. 2016 Dec; 2: 34. Published online 2016 Aug 24. doi: 10.1186/s40798-016-0059-7 PMCID: PMC4996887

Abstract

Background: Some endurance athletes exhibit exercise-induced arterial hypoxemia during high-intensity exercise. Inhalation of hyperoxic gas during exercise has been shown to counteract this exercise-associated reduction in hemoglobin oxygen saturation (SaO2), but the effects of hyperoxic gas inhalation on performance and SaO2 during high-intensity intermittent exercise remain unclear. This study investigated the effects of hyperoxic gas inhalation on performance and SaO2 during high-intensity intermittent cycling exercise.

Conclusion: Hyperoxic gas inhalation during the entire high-intensity intermittent exercise enhanced exercise performance in male cyclists.

https://pubmed.ncbi.nlm.nih.gov/3892251/

von Ardenne M. (1985). Fundamentals of combating cancer metastasis by oxygen multistep immunostimulation processes. Medical hypotheses, 17(1), 47–65. https://doi.org/10.1016/0306-9877(85)90019-2

Abstract

Because more than 80% of all cancer deaths are caused by metastases, development and evaluation of methods for fighting tumor dissemination should be major tasks of present cancer research. Formation of metastases is favoured by both reduced numbers of immune cells in the bloodstream and impaired oxygen transport into tissues. These closely related signs often emerge concomitantly when the organism is endangered by circulating tumor cells released from the original tumor by therapeutic manipulations. From knowledge of these facts the O2-multistep immunostimulation technique has been developed as a way of diminishing the risk of tumor spread. The process combines temporary elevation of the number of circulating immune cells with continuous improvement of oxygen transport into tissues. The former is achieved by a peptide mixture isolated from thymus glands in combination with the chemical immunomodulator 2-cyano-ethyl urea; the latter is the outcome of several variants of the O2-multistep therapy discussed here. The efficiency ranges of the different variants are quantified on the basis of findings that allow assessment of the number of tumor cells which can be destroyed by this treatment. This number may be about 100 times the number of malignant cells that must be killed in terms of an effective metastasis prophylaxis (approximately 3 X 10(5)). The estimated efficiency range represents therefore a not yet fully exhausted preventive and possibly even therapeutic potential. To speed the introduction of the procedures described into practice, all clinical oncologists are encouraged to refer their patients to established facilities for O2-multistep immunostimulation after termination of any conventional therapy.

Title: 

The Potential to Change Pacing and Performance During 4000-m Cycling Time Trials Using Hyperoxia and Inspired Gas-Content Deception

https://pubmed.ncbi.nlm.nih.gov/30676139/

Davies, M. J., Clark, B., Garvican-Lewis, L. A., Welvaert, M., Gore, C. J., & Thompson, K. G. (2019). The Potential to Change Pacing and Performance During 4000-m 

Cycling Time Trials Using Hyperoxia and Inspired Gas-Content Deception. International journal of sports physiology and performance, 14(7), 949–957. 

https://doi.org/10.1123/ijspp.2018-0335

Abstract

Purpose: Determine if a series of trials with fraction of inspired oxygen (FiO2) content deception could improve 4000-m cycling time-trial (TT) performance.

Conclusions: Cycling performance improved with acute exposure to hyperoxia. Mechanisms for the improvement were likely physiological, however improvement in a deception trial suggests an additional placebo effect may be present. Finally, a particular sequence of oxygen deception trials may have built psycho-physiological belief in cyclists such that performance improved in a subsequent normoxic trial.

Title: 

Supplemental Oxygen and Exercise Performance in Patients with Cystic Fibrosis with Severe Pulmonary Disease

https://www.sciencedirect.com/science/article/abs/pii/S0012369216331208

Carole L. Marcus, David Bader, Michael W Stabile, Chun-I Wang, Alan B. Osher, Thomas G. Keens, Supplemental Oxygen and Exercise Performance in Patients with Cystic Fibrosis with Severe Pulmonary Disease, Chest, Volume 101, Issue 1,1992, Pages 52-57, ISSN 0012-3692, https://doi.org/10.1378/chest.101.1.52

Abstract

Patients with cystic fibrosis (CF) and advanced pulmonary disease have pulmonary limitation of exercise, often associated with arterial oxygen desaturation. Improving oxygenation during exercise by providing supplemental oxygen may improve exercise performance in these patients. To test this, we performed graded exercise stress tests in 22 CF patients with severe pulmonary disease (mean PaO2, 64 ±2 mm Hg [±SE]; PaCO2 46 ±2 mm Hg; RV/TLC, 57 ±4 percent; FEV1, 38 ±4 percent of predicted; FEF25-75%, 13 ±2 percent of predicted; median age, 26 years) and compared them to 21 controls (RV/TLC, 27 ± 4 percent; FEV1, 112±2 percent of predicted; FEF25-75%, 80±4 percent of predicted; median age, 29 years). Each subject performed graded exercise stress tests while breathing FIO2 of 0.21 and FIO2 of 0.30. Subjects were blinded to the composition of the inspired gas, and the order of testing was randomized. We found that CF subjects exercised longer, had a higher maximal V˙o2, higher O2 pulse, and less arterial oxygen desaturation when receiving supplemental O2. Control subjects exercised longer when breathing supplemental O2 but had no significant change in maximal V˙o2, O2 pulse, or SaO2. Both CF and control subjects had increased end-tidal PCO2 when exercising while breathing supplemental O2. We conclude that CF patients with advanced pulmonary disease have increased exercise tolerance and aerobic capacity when exercising while breathing supplemental O2. (Chest 1992; 101:52-57)

https://pubmed.ncbi.nlm.nih.gov/28975517/

Mallette, M. M., Stewart, D. G., & Cheung, S. S. (2018). The Effects of Hyperoxia on Sea-Level Exercise Performance, Training, and Recovery: A Meta-Analysis. Sports medicine (Auckland, N.Z.), 48(1), 153–175. https://doi.org/10.1007/s40279-017-0791-2

Abstract

Background: Acute exercise performance can be limited by arterial hypoxemia, such that hyperoxia may be an ergogenic aid by increasing tissue oxygen availability. Hyperoxia during a single bout of exercise performance has been examined using many test modalities, including time trials (TTs), time to exhaustion (TTE), graded exercise tests (GXTs), and dynamic muscle function tests. Hyperoxia has also been used as a long-term training stimulus or a recovery intervention between bouts of exercise. However, due to the methodological differences in fraction of inspired oxygen (FiO2), exercise type, training regime, or recovery protocols, a firm consensus on the effectiveness of hyperoxia as an ergogenic aid for exercise training or recovery remains unclear.

Conclusion: Acute exercise performance is increased with hyperoxia. An FiO2 ≥ 0.30 appears to be beneficial for performance, with a higher FiO2 being correlated to greater performance improvement in TTs, TTE, and dynamic muscle function tests. Exercise training and recovery supplemented with hyperoxic gas appears to have a beneficial effect on subsequent exercise performance, but small sample size and wide disparity in experimental protocols preclude definitive conclusions.

https://pubmed.ncbi.nlm.nih.gov/6711017/

von Ardenne, M., Klemm, W., & Klinger, J. (1984). Doppelblindstudie zur starken anhaltenden Steigerung der körperlichen Leistungsfähigkeit nach Sauerstoff-Mehrschritt-Therapie-Behandlungen [Double-blind study on the long-lasting improvement of physical endurance following oxygen-multistep-therapy]. Zeitschrift fur Alternsforschung, 39(1), 17–30.

Abstract

The characteristic of Oxygen Multistep Therapy is the long-lasting improvement of the energetic or oxygenation state of the organism. This specific effect is confirmed with statistical significance by a two-centric double-blind study on 20 male healthy volunteers from the working population. In this study the ergometrically measurable increase of physical fitness, which was determined two weeks after performance of two 15 min-oxygen-multistep-quick processes, served as over-all criterion. The mean value of the continuing elevation was 17%. On individuals having initially lower physical capacities and therefore being particularly in need of treatment, increases of 25, 33, and even 45% were determined.

https://neurosciencenews-com.cdn.ampproject.org/c/s/neurosciencenews.com/exercise-intensity-brain-15610/amp/

Title

 Effect of breathing oxygen-enriched air on exercise performance in patients with precapillary pulmonary hypertension: randomized, sham-controlled cross-over trial

https://pubmed.ncbi.nlm.nih.gov/28329240/

Ulrich, S., Hasler, E. D., Saxer, S., Furian, M., Müller-Mottet, S., Keusch, S., & Bloch, K. E. (2017). Effect of breathing oxygen-enriched air on exercise performance in patients with precapillary pulmonary hypertension: randomized, sham-controlled cross-over trial. European heart journal, 38(15), 1159–1168. https://doi.org/10.1093/eurheartj/ehx099

Abstract

In patients with Pulmonary arterial or chronic thrombo-embolic pulmonary hypertension (PAH/CTEPH), breathing oxygen-enriched air provides major increases in exercise performance. This is related to an improved arterial oxygenation that promotes oxygen availability in muscles and brain and to a reduction of the excessive ventilatory response to exercise thereby enhancing ventilatory efficiency. Patients with PAH/CTEPH may therefore benefit from oxygen therapy during daily physical activities and training.

Title

Adaptation to intermittent hypoxia-hyperoxia improves cognitive performance and exercise tolerance in elderly

https://pubmed.ncbi.nlm.nih.gov/28575566/

Bayer, U., Glazachev, O. S., Likar, R., Burtscher, M., Kofler, W., Pinter, G., Stettner, H., Demschar, S., Trummer, B., & Neuwersch, S. (2017). Advances in gerontology = Uspekhi gerontologii, 30(2), 255–261.

Abstract

For improvements in exercise tolerance and cognitive function in geriatric patients Multimodal training programs (MTP) are used as combination of physiotherapy, occupational therapy and cardiovascular training. Intermittent Hypoxic-Hyperoxic Training (IHHT), a modified type of intermittent hypoxic training (IHT) is proposed to be included in MTP to elicit more pronounced beneficial effects in exercise tolerance and cognitive functions of geriatric patients likely by an additional pathway than a single MTP. Thirty four patients of the Geriatric Day Clinic aged between 64 and 92 years participated in the placebo controlled clinical trial. They were randomly assigned to receive MTP plus IHHT (experimental group - EG) or MTP plus placebo-breathing through a machine face mask (control group - CG) in a double blind fashion. Before and after the interventions course cognitive performance was assessed by the Dementia-Detection-Test (DemTect) and the Clock-Drawing-Test (CDT), and functional exercise capacity - by the total distance of 6-Minute-Walk-Test (6MWT). After IHHT combined with MTP cognitive performance (DemTect) increased significantly when compared to NG (+16,7 % vs. +0,39 %, p<0,001). The CDT indicated similar results with a significant increase in the EG while the score of the CG even decreased (+10,7 % vs. -8%, p=0,031). Concerning the functional exercise capacity, both groups improved the total distance in the 6MWT but with a significantly larger increase in the EG compared to the CG (+24,1 % vs. +10,8 %, p=0,021). In addition, there was a significant relationship between the changes of the 6MWT and the DemTect Scores and the CDT. IHHT contributed significantly to improvements in cognitive performance and exercise capacity in elderly performing MTP. IHHT sessions are considered to be easily applicable to and well tolerated by geriatric patients up to 92 years.

Title

Energy cost and lower leg muscle activities during erect bipedal locomotion under hyperoxia

https://pubmed.ncbi.nlm.nih.gov/29914562/

Abe, D., Fukuoka, Y., Maeda, T., & Horiuchi, M. (2018). Energy cost and lower leg muscle activities during erect bipedal locomotion under hyperoxia. Journal of physiological anthropology, 37(1), 18. https://doi.org/10.1186/s40101-018-0177-7

Abstract

Background: Energy cost of transport per unit distance (CoT) against speed shows U-shaped fashion in walking and linear fashion in running, indicating that there exists a specific walking speed minimizing the CoT, being defined as economical speed (ES). Another specific gait speed is the intersection speed between both fashions, being called energetically optimal transition speed (EOTS). We measured the ES, EOTS, and muscle activities during walking and running at the EOTS under hyperoxia (40% fraction of inspired oxygen) on the level and uphill gradients (+ 5%).

Conclusions: ES and EOTS were influenced by reduced metabolic demands induced by hyperoxia. GL and TA activities in association with a lower shift of motor unit recruitment patterns in the TA would be related to the gait selection when walking or running at the EOTS.

Title

Effects of mild whole body hypothermia on self-paced exercise performance

https://pubmed.ncbi.nlm.nih.gov/29672229/

Ferguson, S., Eves, N. D., Roy, B. D., Hodges, G. J., & Cheung, S. S. (2018). Effects of mild whole body hypothermia on self-paced exercise performance. Journal of applied physiology (Bethesda, Md. : 1985), 125(2), 479–485. https://doi.org/10.1152/japplphysiol.01134.2017

Abstract

This study examined self-paced, high-intensity exercise during mild hypothermia and whether hyperoxia might offset any potential impairment. Twelve trained males each completed 15-km time trials in three environmental conditions: Neutral (23°C, [Formula: see text] 0.21), Cold (0°C, [Formula: see text] 0.21), and Cold+Hyper (0°C, [Formula: see text] 0.40). Cold and Cold+Hyper trials occurred after a 0.5°C drop in rectal temperature. Rectal temperature was higher ( P ≤ 0.016) throughout Neutral compared with Cold and Cold+Hyper; Cold had a higher ( P ≤ 0.035) rectal temperature than Cold+Hyper from 2.5 to 7.5 km, and hyperoxia did not alter thermal sensation or comfort. Oxyhemoglobin saturation decreased from ~98% to ~94% with Neutral and Cold, but was maintained at ~99% in Cold+Hyper ( P < 0.01). Cerebral tissue oxygenation index (TOI) was higher in Neutral than in Cold throughout the time trial (TT) ( P ≤ 0.001), whereas Cold+Hyper were unchanged ( P ≥ 0.567) from Neutral by 2.5 km. Muscle TOI was maintained in Cold+Hyper compared with Neutral and was higher ( P ≤ 0.046) than Cold throughout the entire TT. Power output during Cold (246 ± 41 W) was lower than Neutral (260 ± 38 W) at all 2.5-km intervals ( P ≤ 0.012) except at 12.5 km. Power output during Cold+Hyper (256 ± 42 W) was unchanged ( P ≥ 0.161) from Neutral throughout the TT, and was higher than Cold from 7.5 km onward. Average cadence was higher in Neutral (93 ± 8 rpm) than in either Cold or Cold+Hyper (Cold: 89 ± 7 and Cold+Hyper: 90 ± 8 rpm, P = 0.031). In conclusion, mild hypothermia reduced self-paced exercise performance; hyperoxia during mild hypothermia restored performance to thermoneutral levels, likely due to maintenance of oxygen availability rather than any thermogenic benefit. NEW & NOTEWORTHY We examined self-paced, high-intensity exercise with 0.5°C rectal temperature decreases in a 0°C ambient environment, along with whether hyperoxia could offset any potential impairment. During a 15-km time trial, power output was lower with hypothermia than with thermoneutral. However, with hypothermia, hyperoxia of [Formula: see text] = 0.40 restored power output despite there being no thermophysiological improvement. Hypothermia impairs exercise performance, whereas hyperoxia likely restored performance due to maintenance of oxygen availability rather than any thermogenic benefit.

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-1716.2007.01713.x

Larsen, F.J., Weitzberg, E., Lundberg, J.O. and Ekblom, B. (2007), Effects of dietary nitrate on oxygen cost during exercise. Acta Physiologica, 191: 59-66. 

https://doi.org/10.1111/j.1748-1716.2007.01713.x

Abstract

Nitric oxide (NO), synthesized from l‐arginine by NO synthases, plays a role in adaptation to physical exercise by modulating blood flow, muscular contraction and glucose uptake and in the control of cellular respiration. The dietary nitrate supplementation, in an amount achievable through a diet rich in vegetables, results in a lower oxygen demand during submaximal work. This highly surprising effect occurred without an accompanying increase in lactate concentration, indicating that the energy production had become more efficient. The mechanism of action needs to be clarified but a likely first step is the in vivo reduction of dietary nitrate into bioactive nitrogen oxides including nitrite and NO.

Title

Hyperoxia enhances self-paced exercise performance to a greater extent in cool than hot conditions

https://pubmed.ncbi.nlm.nih.gov/31290172/

Périard, J. D., Houtkamp, D., Bright, F., Daanen, H., Abbiss, C. R., Thompson, K. G., & Clark, B. (2019). Hyperoxia enhances self-paced exercise performance to a greater extent in cool than hot conditions. Experimental physiology, 104(9), 1398–1407. https://doi.org/10.1113/EP087864

Abstract

Hyperoxia enhances endurance performance by increasing O2 availability to locomotor muscles. We investigated whether hyperoxia can also improve prolonged self-paced exercise in conditions of elevated thermal and cardiovascular strain. Hyperoxia improved self-paced exercise performance in hot and cool conditions. However, the extent of the improvement (increased work rate relative to normoxia) was greater in cool conditions. This suggests that the development of thermal and cardiovascular strain during prolonged self-paced exercise under heat stress might attenuate the hyperoxia-mediated increase in O2 delivery to locomotor muscles.

Title

Hyperoxia speeds pulmonary oxygen uptake kinetics and increases critical power during supine cycling

https://pubmed.ncbi.nlm.nih.gov/31054263/

Goulding, R. P., Roche, D. M., & Marwood, S. (2019). Hyperoxia speeds pulmonary oxygen uptake kinetics and increases critical power during supine cycling. Experimental physiology, 104(7), 1061–1073. https://doi.org/10.1113/EP087599

Abstract

Critical power is a fundamental parameter defining high-intensity exercise tolerance and is related to the phase II time constant of pulmonary oxygen uptake kinetics (ΤVO2). To test whether this relationship is causal, we assessed the impact of hyperoxia on ΤVO2 and critical power during supine cycle exercise. The results demonstrate that hyperoxia increased muscle oxygenation, reduced ΤVO2 (i.e. sped up the oxygen uptake kinetics) and, subsequently, increased critical power when compared with normoxia. These results therefore suggest that ΤVO2 is a determinant of the upper limit for steady-state exercise, i.e. critical power.

https://pubmed.ncbi.nlm.nih.gov/31359633/

Kon, M., Nakagaki, K., & Ebi, Y. (2019). Effects of all-out sprint interval training under hyperoxia on exercise performance. Physiological reports, 7(14), e14194. https://doi.org/10.14814/phy2.14194

Abstract

All-out sprint interval training (SIT) is speculated to be an effective and time-efficient training regimen to improve the performance of aerobic and anaerobic exercises. SIT under hypoxia causes greater improvements in anaerobic exercise performance compared with that under normoxia. The change in oxygen concentration may affect SIT-induced performance adaptations. In this study, we aimed to investigate the effects of all-out SIT under hyperoxia on the performance of aerobic and anaerobic exercises. Eighteen college male athletes were randomly assigned to either the normoxic sprint interval training (NST, n = 9) or hyperoxic (60% oxygen) sprint interval training (HST, n = 9) group and performed 3-week SIT (six sessions) consisting of four to six 30-sec all-out cycling sessions with 4-min passive rest. They performed maximal graded exercise, submaximal exercise, 90-sec maximal exercise, and acute SIT tests on a cycle ergometer before and after the 3-week intervention to evaluate the performance of aerobic and anaerobic exercises. Maximal oxygen uptake significantly improved in both groups. However, blood lactate curve during submaximal exercise test significantly improved only in the HST group. The accumulated oxygen deficit (AOD) during 90-sec maximal exercise test significantly increased only in the NST group. The average values of mean power outputs over four bouts during the acute SIT test significantly improved only in the NST group. These findings suggest that all-out SIT might induce greater improvement in aerobic exercise performance (blood lactate curve) but impair SIT-induced enhancements in anaerobic exercise performance (AOD and mean power output).

https://pubmed.ncbi.nlm.nih.gov/31337587/

Porter, M. S., Fenton, J., & Reed, K. E. (2019). The effects of hyperoxia on repeated sprint cycling performance & muscle fatigue. Journal of science and medicine in sport, 22(12), 1344–1348. https://doi.org/10.1016/j.jsams.2019.07.001

Abstract

Hyperoxia can elicit improvements in mean cycling power, with no significant change in post exercise muscle fatigue. Hyperoxia as a training aid may provide performance enhancing effects during repeated sprint cycling by reducing concurrent muscle fatigue, primarily via peripheral factors.

https://pubmed.ncbi.nlm.nih.gov/29901612/

Freitag, N., Weber, P. D., Sanders, T. C., Schulz, H., Bloch, W., & Schumann, M. (2018). High-intensity interval training and hyperoxia during chemotherapy: A case report about the feasibility, safety and physical functioning in a colorectal cancer patient. Medicine, 97(24), e11068. https://doi.org/10.1097/MD.0000000000011068

Abstract

A case study was conducted to examine the feasibility and safety of high-intensity interval training (HIIT) with increased inspired oxygen content in a colon cancer patient undergoing chemotherapy. A secondary purpose was to investigate the effects of such training regimen on physical functioning. The results show that an already short period of HIIT with concomitant hyperoxia was safe and feasible for a patient undergoing chemotherapy for colon cancer. Furthermore, the low overall training adherence of only 51% and an overall low training time per session (∼13 minutes) was sufficient to induce clinically meaningful improvements in physical functioning. However, this case also underlines that intensity and/or length of the HIIT-bouts might need further adjustments to increase training compliance.

Title

Adaptations following an intermittent hypoxia-hyperoxia training in coronary artery disease patients: a controlled study

https://pubmed.ncbi.nlm.nih.gov/28323322/

Glazachev, O., Kopylov, P., Susta, D., Dudnik, E., & Zagaynaya, E. (2017). Adaptations following an intermittent hypoxia-hyperoxia training in coronary artery disease patients: a controlled study. Clinical cardiology, 40(6), 370–376. https://doi.org/10.1002/clc.22670

Abstract

Repeated exposure to intermittent normobaric hypoxia improves exercise tolerance in cardiac patients. Little is known on the effects of intermittent normobaric hypoxia-hyperoxia exposure in coronary artery disease (CAD) patients (New York Heart Association II-III). In CAD patients, an IHHT program is associated with improved exercise tolerance, healthier risks factors profile, and a better quality of life. Our study also suggests that IHHT is as effective as an 8-week standard rehabilitation program.

https://pubmed.ncbi.nlm.nih.gov/28108650/

Manselin, T. A., Södergård, O., Larsen, F. J., & Lindholm, P. (2017). Aerobic efficiency is associated with the improvement in maximal power output during acute hyperoxia. Physiological reports, 5(2), e13119. https://doi.org/10.14814/phy2.13119

Abstract

This study investigated the relationship between aerobic efficiency during cycling exercise and the increase in physical performance with acute hyperoxic exposure (FiO2 ~31%) (HOX) and also tested the hypothesis that fat oxidation could be increased by acute hyperoxia. Fourteen males and four females were recruited for two sessions, where they exercised for 2 × 10 min at 100 W to determine efficiency. HOX and normoxia (NOX) were administered randomly on both occasions to account for differences in nitrogen exchange. Thereafter, a progressive ramp test was performed to determine VO2max and maximal power output (Wmax). After 30 min rest, workload was set to 80% of maximal power output (Wmax) for a time to exhaustion test (TTE). At 100W gross efficiency was reduced from 19.4% during NOX to 18.9% during HOX (P ≤ 0.0001). HOX increased fat oxidation at 100 W by 52% from 3.41 kcal min-1 to 5.17 kcal min-1 (P ≤ 0.0001) with a corresponding reduction in carbohydrate oxidation. Wmax increased by 2.4% from 388.8 (±82.1) during NOX to 397.8 (±83.5) during HOX (P ≤ 0.0001). SaO2 was higher in HOX both at the end of the maximal exercise test and TTE. Subjects with a high level of efficiency in NOX had a larger improvement in Wmax with HOX, in agreement with the hypothesis that an optimum level of efficiency exists that maximizes power production. No association between mitochondrial excess capacity and endurance performance was found; increases in oxygen supply seemed to increase maximal aerobic power production and maintain/increase endurance capacity at the same relative workload.

https://pubmed.ncbi.nlm.nih.gov/28068656/

Ulrich, S., Hasler, E. D., Müller-Mottet, S., Keusch, S., Furian, M., Latshang, T. D., Schneider, S., Saxer, S., & Bloch, K. E. (2017). Mechanisms of Improved Exercise Performance under Hyperoxia. Respiration; international review of thoracic diseases, 93(2), 90–98. https://doi.org/10.1159/000453620

Abstract

In healthy subjects, hyperoxia increased maximal power output and endurance. It improved arterial, cerebral, and muscle tissue oxygenation, while minute ventilation and dyspnea perception were reduced. The findings suggest that hyperoxia enhanced cycling performance through a more efficient pulmonary gas exchange and a greater availability of oxygen to muscles and the brain (cerebral motor and sensory neurons).

https://pubmed.ncbi.nlm.nih.gov/26769951/

Smith, K. J., Wildfong, K. W., Hoiland, R. L., Harper, M., Lewis, N. C., Pool, A., Smith, S. L., Kuca, T., Foster, G. E., & Ainslie, P. N. (2016). Role of CO2 in the cerebral hyperemic response to incremental normoxic and hyperoxic exercise. Journal of applied physiology (Bethesda, Md. : 1985), 120(8), 843–854. https://doi.org/10.1152/japplphysiol.00490.2015

Abstract

Cerebral blood flow (CBF) is temporally related to exercise-induced changes in partial pressure of end-tidal carbon dioxide (PetCO2 ); hyperoxia is known to enhance this relationship. We examined the hypothesis that preventing PetCO2 from rising (isocapnia) during submaximal exercise with and without hyperoxia [end-tidal Po2(PetO2 ) = 300 mmHg] would attenuate the increases in CBF. Additionally, we aimed to identify the magnitude that breathing, per se, influences the CBF response to normoxic and hyperoxic exercise. In 14 participants, CBF (intra- and extracranial) measurements were measured during exercise [20, 40, 60, and 80% of maximum workload (Wmax)] and during rest while ventilation (V̇e) was volitionally increased to mimic volumes achieved during exercise (isocapnic hyperpnea). While V̇ewas uncontrolled during poikilocapnic exercise, during isocapnic exercise and isocapnic hyperpnea, V̇ewas increased to prevent PetCO2 from rising above resting values (∼40 mmHg). Although PetCO2 differed by 2 ± 3 mmHg during normoxic poikilocapnic and isocapnic exercise, except for a greater poikilocapnic compared with isocapnic increase in blood velocity in the posterior cerebral artery at 60% Wmax, the between condition increases in intracranial (∼12-15%) and extracranial (15-20%) blood flow were similar at each workload. The poikilocapnic hyperoxic increases in both intra- and extracranial blood-flow (∼17-29%) were greater compared with poikilocapnic normoxia (∼8-20%) at intensities >40% Wmax(P< 0.01). During both normoxic and hyperoxic conditions, isocapnia normalized both the intracranial and extracranial blood-flow differences. Isocapnic hyperpnea did not alter CBF. Our findings demonstrate a differential effect of PetCO2 on CBF during exercise influenced by the prevailing PetO2.

https://pubmed.ncbi.nlm.nih.gov/26744210/

Rozenberg, R., Mankowski, R. T., van Loon, L. J., Langendonk, J. G., Sijbrands, E. J., van den Meiracker, A. H., Stam, H. J., & Praet, S. F. (2016). Hyperoxia increases arterial oxygen pressure during exercise in type 2 diabetes patients: a feasibility study. European journal of medical research, 21, 1. https://doi.org/10.1186/s40001-015-0194-5

Abstract

The study investigated the feasibility and potential outcome measures during acute hyperoxia in type 2 diabetes patients (DM2). An SOF of 15 L min(-1) appears to be more effective than 5 or 10 L min(-1). Moreover, HR, blood pressure, blood lactate and pH are not recommended as primary outcome measures.

https://pubmed.ncbi.nlm.nih.gov/24476781/

Yokoi, Y., Yanagihashi, R., Morishita, K., Goto, N., Fujiwara, T., & Abe, K. (2014). Recovery effects of repeated exposures to normobaric hyperoxia on local muscle fatigue. Journal of strength and conditioning research, 28(8), 2173–2179. https://doi.org/10.1519/JSC.0000000000000386

Abstract

Reported recovery effects of hyeroxia are conflicted. This study aimed to identify the effects and the mechanisms of normobaric hyperoxia on the recovery of local muscle fatigue, which is the most commonly encountered form of fatigue both daily and in training and competitions. Twelve male subjects performed 3 × 3 × no less than 30 seconds of isometric quadriceps exercise at 70% of maximum voluntary isometric contraction (MVIC) separated by two 15-minute recovery sessions under 1 of 2 different atmospheric oxygen concentrations, one in normoxia (NOX; 20.9% O2) and another in hyperoxia (HOX; 30.0% O2). To assess the degree of fatigue and recovery, 4 parameters were used; MVIC, endurance time to exhaustion, blood lactate, and perceived exertion measured by a visual analog scale (VAS). Maximum voluntary isometric contraction improved an average by approximately 14% in HOX compared with NOX at the conclusion of the second recovery session. However, this was not associated with changes in other parameters because changes in endurance time, blood lactate, and VAS during the trials were similar. Based on our findings, we conclude that 2 sets of 15-minute recovery session in normobaric hyperoxia are effective for restoring MVIC from local muscle fatigue induced by intermittent intense exercises. For quicker recovery, athletes are recommended to repeat 15-minute recovery process under 30.0% hyperoxia.

https://pubmed.ncbi.nlm.nih.gov/27427325/

Neunhäuserer, D., Steidle-Kloc, E., Weiss, G., Kaiser, B., Niederseer, D., Hartl, S., Tschentscher, M., Egger, A., Schönfelder, M., Lamprecht, B., Studnicka, M., & Niebauer, J. (2016). Supplemental Oxygen During High-Intensity Exercise Training in Nonhypoxemic Chronic Obstructive Pulmonary Disease. The American journal of medicine, 129(11), 1185–1193. https://doi.org/10.1016/j.amjmed.2016.06.023

Abstract

Background: Physical exercise training is an evidence-based treatment in chronic obstructive pulmonary disease, and patients' peak work rate is associated with reduced chronic obstructive pulmonary disease mortality. We assessed whether supplemental oxygen during exercise training in nonhypoxemic patients with chronic obstructive pulmonary disease might lead to superior training outcomes, including improved peak work rate.

Conclusions: We report that supplemental oxygen in nonhypoxemic chronic obstructive pulmonary disease doubled the effect of endurance training but had no effect on strength gain.

https://pubmed.ncbi.nlm.nih.gov/32192916/

Margaritelis, N. V., Paschalis, V., Theodorou, A. A., Kyparos, A., & Nikolaidis, M. G. (2020). Redox basis of exercise physiology. Redox biology, 35, 101499. https://doi.org/10.1016/j.redox.2020.101499

Abstract

Redox reactions control fundamental processes of human biology. Therefore, it is safe to assume that the responses and adaptations to exercise are, at least in part, mediated by redox reactions. In this review, we are trying to show that redox reactions are the basis of exercise physiology by outlining the redox signaling pathways that regulate four characteristic acute exercise-induced responses (muscle contractile function, glucose uptake, blood flow and bioenergetics) and four chronic exercise-induced adaptations (mitochondrial biogenesis, muscle hypertrophy, angiogenesis and redox homeostasis). Based on our analysis, we argue that redox regulation should be acknowledged as central to exercise physiology.

https://pubmed.ncbi.nlm.nih.gov/32179050/

Cheng, A. J., Jude, B., & Lanner, J. T. (2020). Intramuscular mechanisms of overtraining. Redox biology, 35, 101480. https://doi.org/10.1016/j.redox.2020.101480

Abstract

Strenuous exercise is a potent stimulus to induce beneficial skeletal muscle adaptations, ranging from increased endurance due to mitochondrial biogenesis and angiogenesis, to increased strength from hypertrophy. While exercise is necessary to trigger and stimulate muscle adaptations, the post-exercise recovery period is equally critical in providing sufficient time for metabolic and structural adaptations to occur within skeletal muscle. These cyclical periods between exhausting exercise and recovery form the basis of any effective exercise training prescription to improve muscle endurance and strength. However, imbalance between the fatigue induced from intense training/competitions, and inadequate post-exercise/competition recovery periods can lead to a decline in physical performance. In fact, prolonged periods of this imbalance may eventually lead to extended periods of performance impairment, referred to as the state of overreaching that may progress into overtraining syndrome (OTS). OTS may have devastating implications on an athlete's career and the purpose of this review is to discuss potential underlying mechanisms that may contribute to exercise-induced OTS in skeletal muscle. First, we discuss the conditions that lead to OTS, and their potential contributions to impaired skeletal muscle function. Then we assess the evidence to support or refute the major proposed mechanisms underlying skeletal muscle weakness in OTS: 1) glycogen depletion hypothesis, 2) muscle damage hypothesis, 3) inflammation hypothesis, and 4) the oxidative stress hypothesis. Current data implicates reactive oxygen and nitrogen species (ROS) and inflammatory pathways as the most likely mechanisms contributing to OTS in skeletal muscle. Finally, we allude to potential interventions that can mitigate OTS in skeletal muscle.

"If there's one thing that mitochondria thrive on, its oxygen. All of it is consumed by cytochrome oxidase, the last enzyme in the electron transport chain which drives ATP production. If cells relied on diffusion alone to supply them with their oxygen needs, then there would not be enough to keep up with demand. So oxygen carrying molecules, such as hemoglobin and myoglobin transport oxygen to where it is needed... As oxygen travels through the body it exerts a pressure in the mixture of gases in the lungs, or in solution, known as the partial pressure. Oxygen bound to hemoglobin in the blood diffuses down a steep pressure gradient into tissues as blood travels through capillaries. Next oxygen diffuses into the mitochondria." From a 2007 edition of the Journal of Experimental Biology (O2 Uptake in Mitochondria)

"It has been shown that 95% of all oxygen utilized in the body is involved with a subcellular structure known as mitochondria." Taken from the transcript of a lecture given by Dr. Roger Orth (The Role of Mitochondria in Aging)

"Most of the energy for endurance exercise comes from oxidation of fuel. The maximal capacity of an individual to consume oxygen is therefore one of the important factors limiting endurance performance. Mitochondrial DNA is of particular interest, because it contains the genes for several enzymes involved in oxygen consumption." From a 2001 issue of Sportscience (Mitochondrial DNA and Maximum Oxygen Consumption)

"Mitochondria play a central role in cell life and cell death. An increasing number of studies place mitochondrial dysfunction at the heart of disease, most notably in the heart and the central nervous system. That we must breathe oxygen to stay alive is simply the consequence of the demand of our mitochondria for oxygen. About 98% of inhaled oxygen is consumed by mitochondria, and without mitochondria, we would have no need of the oxygen transfer machinery of the lungs, red cells, hemoglobin, or even the circulatory system that delivers oxygen to the tissues. Similarly, the organization of food intake, digestion, and processing is designed primarily to supply substrates destined for mitochondrial oxidation. Consider then how much of the physiology of higher organisms is dictated by the demand of our mitochondria for a supply of oxygen." From the February 2004 issue of the medical journal Diabetes (Roles of Mitochondria in Health and Disease)

"During the last 20 years, gerontological studies have revealed different molecular pathways involved in the ageing process and pointed out mitochondria as one of the key regulators of longevity. Increasing age in mammals correlates with increased levels of mitochondrial DNA mutations and a deteriorating respiratory chain function." From the July 2010 issue of Biochimica et Biophysica Acta - Bioenergetics (Mitochondrial Energy Metabolism and Ageing)

"It is generally accepted that mitochondria play an important role in cancer through replication and energy production. By oxidizing (losing an electron) the fat, protein, and carbohydrates we consume through food and drink, they create energy-abundant molecules (ATP) for the cell through biochemical processes known as cellular respiration. Normal cells produce energy through mitochondrial oxidative phosphorylation (OXPHOS). When oxygen is not available, they produce energy via the less efficient route of anaerobic glycolysis. In the 1920s, Otto Warburg observed that cancer cells do not produce energy in the efficient way that normal cells do. Rather, cancer cells produce most of their energy through an inefficient, high rate of glycolysis followed by fermentation of lactate into lactic acid. Glucose is then diverted from producing ATP to a process to promote cell proliferation. This process was coined by Warburg himself as aerobic fermentation, which has been adapted to 'aerobic glycolysis', and commonly known as the Warburg Effect. All evidence supports the Warburg effect - whether causal or not - as constant in the initiation and/or progression of cancer." Dr. Michael Karlfeldt from the September 2018 issue of the Townsend Letter (The Link Between Cancer and Mitochondria: Restoring Mitochondrial Function to Fight Cancer)