{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T23:45:42Z","timestamp":1787615142912,"version":"build-2736575974"},"reference-count":93,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,1,3]],"date-time":"2026-01-03T00:00:00Z","timestamp":1767398400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background: Carbon dioxide (CO2) is traditionally regarded as a metabolic by-product; however, growing evidence indicates that it plays an active regulatory role across multiple physiological systems. Acute hypercapnia elicits respiratory, cardiovascular, metabolic, immune, and neurocognitive responses, some of which may transiently influence exercise performance. This narrative review summarizes current evidence on CO2 inhalation in healthy individuals and critically evaluates whether controlled hypercapnia may serve as a targeted stimulus in sport and exercise contexts. Methods: A narrative review of peer-reviewed English-language articles indexed in PubMed and Web of Science was conducted. A narrative approach was chosen due to the marked heterogeneity of study designs, hypercapnia-induction methods (e.g., CO2 inhalation, voluntary hypoventilation, increased respiratory dead space), participant characteristics, and outcome measures, which precluded systematic synthesis. The review focused on studies involving healthy or physically active individuals and examined acute or short-term hypercapnic exposure. No strict publication date limits were applied. Studies conducted exclusively in clinical populations were excluded. Results: Short-term, controlled hypercapnia reliably increases ventilation, sympathetic activation, cerebral and muscular blood flow, and metabolic stress. Certain hypercapnia-based interventions\u2014such as voluntary hypoventilation or added respiratory dead space\u2014may enhance buffering capacity, reduce lactate accumulation and improve maximal oxygen uptake (VO2max) during submaximal efforts and repeated-sprint performance during high-intensity, short-duration exercise. However, CO2 inhalation frequently induces dyspnea, anxiety, and cognitive disruption, and higher concentrations pose clear safety risks. Current evidence does not support long-term improvements in VO2max or long-duration endurance performance following hypercapnia-based interventions. Conclusions: Controlled, intermittent hypercapnia may provide a targeted metabolic and ventilatory stimulus that enhances tolerance to high-intensity exercise, yet its application remains experimental and context-dependent. The risks associated with CO2 inhalation in healthy individuals currently outweigh its potential benefits, and safe, effective training protocols have not been fully established. Further research is needed to clarify the mechanisms, long-term adaptations, and practical utility of hypercapnia-based training strategies.<\/jats:p>","DOI":"10.3390\/jcm15010364","type":"journal-article","created":{"date-parts":[[2026,1,5]],"date-time":"2026-01-05T10:53:50Z","timestamp":1767610430000},"page":"364","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Carbon Dioxide Inhalation\u2014Risks for Health or Opportunity for Physical Fitness Development?"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7697-6881","authenticated-orcid":false,"given":"Natalia","family":"Danek","sequence":"first","affiliation":[{"name":"Department of Physiology and Biomechanics, Faculty of Physical Education and Sport, Wroclaw University of Health and Sport Sciences, 51-612 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,3]]},"reference":[{"key":"ref_1","unstructured":"Patel, N., and Sharma, S. (2023). Respiratory Acidosis. StatPearls, StatPearls Publishing. Available online: https:\/\/www.ncbi.nlm.nih.gov\/books\/NBK482430\/."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/S0022-3476(48)80025-9","article-title":"Respiratory acidosis and alkalosis in children","volume":"32","author":"Spector","year":"1948","journal-title":"J. Pediatr."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"R1473","DOI":"10.1152\/ajpregu.91008.2008","article-title":"Integration of cerebrovascular CO2 reactivity and chemoreflex control of breathing: Mechanisms of regulation, measurement, and interpretation","volume":"296","author":"Ainslie","year":"2009","journal-title":"Am. J. Physiol. Regul. Integr. Comp. Physiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1007\/s00134-016-4261-3","article-title":"Understanding the Haldane effect","volume":"43","author":"Teboul","year":"2017","journal-title":"Intensive Care Med."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"831","DOI":"10.1007\/s00018-013-1470-6","article-title":"Carbon dioxide-sensing in organisms and its implications for human disease","volume":"71","author":"Cummins","year":"2014","journal-title":"Cell. Mol. Life Sci."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Osorio-Rodr\u00edguez, E., Correa-Guerrero, J., Rodelo-Barrios, D., Bonilla-Llanos, M., Rebolledo-Maldonado, C., Pati\u00f1o-Pati\u00f1o, J., Viera-Torres, J., Arias-G\u00f3mez, M., Gracia-Ordo\u00f1ez, M., and Gonz\u00e1lez-Betancur, D. (2025). Hypercapnia as a double-edged modulator of innate immunity and alveolar epithelial repair: A PRISMA-ScR scoping review. Int. J. Mol. Sci., 26.","DOI":"10.3390\/ijms26199622"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1016\/S0301-0082(99)00008-8","article-title":"CO2, brainstem chemoreceptors and breathing","volume":"59","author":"Nattie","year":"1999","journal-title":"Prog. Neurobiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1511","DOI":"10.1002\/j.2040-4603.2014.tb00589.x","article-title":"Regulation of breathing and autonomic outflows by chemoreceptors","volume":"4","author":"Guyenet","year":"2014","journal-title":"Compr. Physiol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"216","DOI":"10.1080\/10615806.2019.1570803","article-title":"Subjective and physiological responses to the 35% carbon dioxide challenge in healthy and non-clinical control populations: A meta-analysis and systematic review","volume":"32","author":"Liu","year":"2019","journal-title":"Anxiety Stress Coping"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.envint.2018.08.059","article-title":"Effects of low-level inhalation exposure to carbon dioxide in indoor environments: A short review on human health and psychomotor performance","volume":"121","author":"Azuma","year":"2018","journal-title":"Environ. Int."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1111\/j.0953-8194.2004.01158.x","article-title":"Acute carbon dioxide exposure in healthy adults: Evaluation of a novel means of investigating the stress response","volume":"16","author":"Kaye","year":"2004","journal-title":"J. Neuroendocrinol."},{"key":"ref_12","first-page":"797","article-title":"CO2 challenge induced HPA axis activation in panic","volume":"10","author":"Schruers","year":"2007","journal-title":"Int. J. Neuropsychopharmacol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1038\/s41893-019-0323-1","article-title":"Direct human health risks of increased atmospheric carbon dioxide","volume":"2","author":"Jacobson","year":"2019","journal-title":"Nat. Sustain."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Carr, J.M.J.R., Ainslie, P.N., and Day, T. (Exp. Physiol., 2025). Confined spaces in space: Cerebral implications of chronic elevations of inspired carbon dioxide and implications for long-duration space travel, Exp. Physiol., Advance online publication.","DOI":"10.1113\/EP091659"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1016\/j.slsci.2015.09.002","article-title":"Interactions between sleep, stress, and metabolism","volume":"8","author":"Hirotsu","year":"2015","journal-title":"Sleep Sci."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Salcedo-Betancourt, J.D., and Moe, O.W. (2024). The effects of acid on calcium and phosphate metabolism. metabolism. Int. J. Mol. Sci., 25.","DOI":"10.3390\/ijms25042081"},{"key":"ref_17","first-page":"39","article-title":"CO2 challenge results in hypothalamic-pituitary-adrenal activation in healthy volunteers","volume":"19","author":"Schruers","year":"2005","journal-title":"J. Psychopharmacol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1038\/jcbfm.2010.153","article-title":"The influence of carbon dioxide on brain activity and metabolism in conscious humans","volume":"31","author":"Xu","year":"2011","journal-title":"J. Cereb. Blood Flow Metab."},{"key":"ref_19","first-page":"6405","article-title":"Magnetic resonance imaging of vascular oxygenation with carbogen (95% O2 5% CO2)","volume":"52","author":"Zhang","year":"2011","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1016\/0165-1781(94)90085-X","article-title":"Carbon dioxide\/oxygen challenge test in panic disorder","volume":"52","author":"Perna","year":"1994","journal-title":"Psychiatry Res."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Griez, E.J., Colasanti, A., van Diest, R., Salamon, E., and Schruers, K. (2007). Carbon dioxide inhalation induces dose-dependent and age-related negative affectivity. PLoS ONE, 2.","DOI":"10.1371\/journal.pone.0000987"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"923","DOI":"10.1016\/S0006-3223(98)00241-8","article-title":"The 35% CO2 inhalation procedure: Test-retest reliability","volume":"45","author":"Coryell","year":"1999","journal-title":"Biol. Psychiatry"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1177\/0269881111415729","article-title":"The effects of 7.5% carbon dioxide inhalation on task performance in healthy volunteers","volume":"26","author":"Diaper","year":"2012","journal-title":"J. Psychopharmacol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"340","DOI":"10.1016\/j.intimp.2015.04.031","article-title":"Effect of elevated carbon dioxide on bronchial epithelial innate immune receptor response to organic dust from swine confinement barns","volume":"27","author":"Schneberger","year":"2015","journal-title":"Int. Immunopharmacol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"13508","DOI":"10.1038\/s41598-018-32008-x","article-title":"Hypercapnia alters expression of immune response genes in airway epithelial cells","volume":"8","author":"Wang","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"47","DOI":"10.5114\/ceji.2021.105245","article-title":"Effect of acute isooxic hypercapnia on oxidative activity of systemic neutrophils in endotoxemic rabbits","volume":"46","author":"Billert","year":"2021","journal-title":"Cent. Eur. J. Immunol."},{"key":"ref_27","first-page":"5","article-title":"Carbon dioxide and MAPK signalling: Towards therapy for inflammation and related processes","volume":"28","author":"Jarmuszkiewicz","year":"2023","journal-title":"Cell. Mol. Biol. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1113\/expphysiol.2004.027250","article-title":"The effects of breathing 5% carbon dioxide on human cardiovascular responses and tolerance to orthostatic stress","volume":"89","author":"Howden","year":"2004","journal-title":"Exp. Physiol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1540","DOI":"10.1111\/ina.12823","article-title":"Respiratory performance of humans exposed to moderate levels of carbon dioxide","volume":"31","author":"Mishra","year":"2021","journal-title":"Indoor Air"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1557","DOI":"10.1038\/npp.2011.15","article-title":"Inhalation of 7.5% carbon dioxide increases threat processing in humans","volume":"36","author":"Garner","year":"2011","journal-title":"Neuropsychopharmacology"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1002\/da.20048","article-title":"Behavioral and cardiovascular effects of 7.5% CO2 in human volunteers","volume":"21","author":"Bailey","year":"2005","journal-title":"Depress. Anxiety"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2635616","DOI":"10.1155\/2022\/2635616","article-title":"Hypercapnia from physiology to practice","volume":"2022","year":"2022","journal-title":"Int. J. Clin. Pract."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1671","DOI":"10.1289\/ehp.1104789","article-title":"Is CO2 an indoor pollutant? Direct effects of low-to-moderate carbon dioxide concentrations on human decision-making performance","volume":"120","author":"Satish","year":"2012","journal-title":"Environ. Health Perspect."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1080\/15459624.2015.1076160","article-title":"High indoor CO2 concentrations in an office environment increases the transcutaneous CO2 level and sleepiness during cognitive work","volume":"13","author":"Lindholm","year":"2016","journal-title":"J. Occup. Environ. Hyg."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"3039","DOI":"10.1113\/jphysiol.2011.206052","article-title":"The cerebrovascular response to carbon dioxide in humans","volume":"589","author":"Fisher","year":"2011","journal-title":"J. Physiol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1186\/s40635-019-0239-0","article-title":"The role of hypercapnia in acute respiratory failure","volume":"7","author":"Bos","year":"2019","journal-title":"Intensive Care Med. Exp."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"896","DOI":"10.1113\/EP085024","article-title":"The ventilatory response to muscle afferent activation during concurrent hypercapnia in humans: Central and peripheral mechanisms","volume":"100","author":"Bruce","year":"2015","journal-title":"Exp. Physiol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1002\/j.2040-4603.2012.tb00403.x","article-title":"Central chemoreceptors: Locations and functions","volume":"2","author":"Nattie","year":"2012","journal-title":"Compr. Physiol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1007\/s00421-010-1352-7","article-title":"No effect of skin temperature on human ventilation response to hypercapnia during light exercise with a normothermic core temperature","volume":"109","author":"Greiner","year":"2010","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1136\/bjsm.29.2.129","article-title":"The relationship between carbon dioxide sensitivity and sprint or endurance performance in young swimmers","volume":"29","author":"McGurk","year":"1995","journal-title":"Br. J. Sports Med."},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Shigemura, M., Welch, L.C., and Sznajder, J.I. (2020). Hypercapnia regulates gene expression and tissue function. Front. Physiol., 11.","DOI":"10.3389\/fphys.2020.598122"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1007\/BF00421837","article-title":"Ventilatory response to hypercapnia in sprint and long-distance swimmers","volume":"43","author":"Ohkuwa","year":"1980","journal-title":"Eur. J. Appl. Physiol. Occup. Physiol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1007\/s00421-011-1968-2","article-title":"Adaptation of the respiratory controller contributes to the attenuation of exercise hyperpnea in endurance-trained athletes","volume":"112","author":"Miyamoto","year":"2012","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1007\/s00421-005-0046-z","article-title":"Effect of hypercapnia on changes in blood pH, plasma lactate and ammonia due to exercise","volume":"95","author":"Kato","year":"2005","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_45","first-page":"63","article-title":"Effect of respiratory acidosis on metabolism in exercise","volume":"53","author":"Ehrsam","year":"1982","journal-title":"J. Appl. Physiol. Respir. Environ. Exerc. Physiol."},{"key":"ref_46","first-page":"959","article-title":"Effect of pH on cardiorespiratory and metabolic responses to exercise","volume":"43","author":"Jones","year":"1977","journal-title":"J. Appl. Physiol. Respir. Environ. Exerc. Physiol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/j.mvr.2011.08.005","article-title":"Effects of acute hypercapnia on the amplitude of cerebrovascular pulsation in humans registered with a non-invasive method","volume":"83","author":"Frydrychowski","year":"2012","journal-title":"Microvasc. Res."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"880","DOI":"10.1152\/japplphysiol.91292.2008","article-title":"Onset responses of ventilation and cerebral blood flow to hypercapnia in humans: Rest and exercise","volume":"106","author":"Ogoh","year":"2009","journal-title":"J. Appl. Physiol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"244","DOI":"10.1152\/japplphysiol.00820.2007","article-title":"Short-term modulation of the exercise ventilatory response in young men","volume":"104","author":"Wood","year":"2008","journal-title":"J. Appl. Physiol."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1002\/j.2040-4603.2012.tb00399.x","article-title":"Peripheral chemoreceptors: Function and plasticity of the carotid body","volume":"2","author":"Kumar","year":"2012","journal-title":"Compr. Physiol."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1016\/j.resp.2007.01.007","article-title":"Adequate stimuli of the carotid body: More than an oxygen sensor?","volume":"157","author":"Kumar","year":"2007","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_52","first-page":"88","article-title":"Circulatory and respiratory response to exercise with added respiratory dead space","volume":"12","year":"2011","journal-title":"Hum. Mov."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1016\/j.resp.2009.07.001","article-title":"Breathing mechanics during exercise with added dead space reflect mechanisms of ventilatory control","volume":"168","author":"Wood","year":"2009","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1152\/jappl.1991.70.1.55","article-title":"Respiratory adaptations to dead space loading during maximal incremental exercise","volume":"70","author":"McParland","year":"1991","journal-title":"J. Appl. Physiol."},{"key":"ref_55","doi-asserted-by":"crossref","unstructured":"Danek, N., Michalik, K., Smolarek, M., and Zato\u0144, M. (2020). Acute effects of using added respiratory dead space volume in a cycling sprint interval exercise protocol: A cross-over study. Int. J. Environ. Res. Public Health, 17.","DOI":"10.3390\/ijerph17249485"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"591","DOI":"10.1152\/jappl.1992.73.2.591","article-title":"Potentiation of exercise ventilatory response by airway CO2 and dead space loading","volume":"73","author":"Poon","year":"1992","journal-title":"J. Appl. Physiol."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1016\/j.resp.2016.01.001","article-title":"Computational simulation of temperature and velocity distribution in human upper respiratory airway during inhalation of hot air","volume":"223","author":"Salimi","year":"2016","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.resp.2016.05.001","article-title":"The effect of exercise training with an additional inspiratory load on inspiratory muscle fatigue and time-trial performance","volume":"230","author":"McEntire","year":"2016","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"371","DOI":"10.1111\/j.1748-1716.2011.02342.x","article-title":"Increased steady-state VO2 and larger O2 deficit with CO2 inhalation during exercise","volume":"204","author":"Ostergaard","year":"2012","journal-title":"Acta Physiol."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"568","DOI":"10.1152\/jappl.1986.60.2.568","article-title":"Skeletal muscle lactate release and glycolytic intermediates during hypercapnia","volume":"60","author":"Graham","year":"1986","journal-title":"J. Appl. Physiol."},{"key":"ref_61","first-page":"R1522","article-title":"Lactate metabolism during exercise: Analysis by an integrative systems model","volume":"277","author":"Cabrera","year":"1999","journal-title":"Am. J. Physiol."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"286","DOI":"10.1249\/00005768-198204000-00006","article-title":"The effects of hypercapnia on the metabolic response to steady-state exercise","volume":"14","author":"Graham","year":"1982","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"6","DOI":"10.1007\/BF00760793","article-title":"The influence of a respiratory acidosis on the exercise blood lactate response","volume":"63","author":"McLellan","year":"1991","journal-title":"Eur. J. Appl. Physiol. Occup. Physiol."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"R638","DOI":"10.1152\/ajpregu.00132.2022","article-title":"Influence of graded hypercapnia on endurance exercise performance in healthy humans","volume":"323","author":"Ryan","year":"2022","journal-title":"Am. J. Physiol. Regul. Integr. Comp. Physiol."},{"key":"ref_65","doi-asserted-by":"crossref","unstructured":"Danek, N., Michalik, K., and Zato\u0144, M. (2022). Warm-up with added respiratory dead space volume mask improves the performance of the cycling sprint interval exercise: Cross-over study. Front. Physiol., 13.","DOI":"10.3389\/fphys.2022.812221"},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"E316","DOI":"10.1152\/ajpendo.2000.278.2.E316","article-title":"Effect of induced metabolic alkalosis on human skeletal muscle metabolism during exercise","volume":"278","author":"Parolin","year":"2000","journal-title":"Am. J. Physiol. Endocrinol. Metab."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1007\/BF00583833","article-title":"Lactic acid permeation rate in working gastrocnemii of dogs during metabolic alkalosis and acidosis","volume":"356","author":"Hirche","year":"1975","journal-title":"Pflugers Arch."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1016\/j.resp.2018.01.002","article-title":"The effect of metabolic alkalosis on the ventilatory response in healthy subjects","volume":"249","author":"Oppersma","year":"2018","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_69","first-page":"441","article-title":"Repeated sprint ability with voluntary hypoventilation","volume":"5","author":"Woorons","year":"2010","journal-title":"Int. J. Sports Physiol. Perform."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"75","DOI":"10.1016\/j.resp.2007.02.017","article-title":"Prolonged expiration down to residual volume leads to severe arterial hypoxemia in athletes during submaximal exercise","volume":"158","author":"Woorons","year":"2007","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_71","doi-asserted-by":"crossref","unstructured":"Woodward, M., and Debold, E.P. (2018). Acidosis and phosphate directly reduce myosin\u2019s force-generating capacity through distinct molecular mechanisms. Front. Physiol., 9.","DOI":"10.3389\/fphys.2018.00862"},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"C173","DOI":"10.1152\/ajpcell.00172.2008","article-title":"Effect of low pH on single skeletal muscle myosin mechanics and kinetics","volume":"295","author":"Debold","year":"2008","journal-title":"Am. J. Physiol. Cell Physiol."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1113\/jphysiol.1997.sp022009","article-title":"The effect of intracellular pH on contractile function of intact, single fibres of mouse muscle declines with increasing temperature","volume":"500","author":"Westerblad","year":"1997","journal-title":"J. Physiol."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"481","DOI":"10.1113\/jphysiol.2005.086801","article-title":"Metabolic alkalosis reduces exercise-induced acidosis and potassium accumulation in human skeletal muscle interstitium","volume":"566","author":"Street","year":"2005","journal-title":"J. Physiol."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"358","DOI":"10.1152\/japplphysiol.91599.2008","article-title":"Fatigue in working muscles","volume":"106","author":"Allen","year":"2009","journal-title":"J. Appl. Physiol."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"R152","DOI":"10.1152\/ajpregu.2000.279.1.R152","article-title":"Enhanced sarcoplasmic reticulum Ca2+ release following intermittent sprint training","volume":"279","author":"Ortenblad","year":"2000","journal-title":"Am. J. Physiol. Regul. Integr. Comp. Physiol."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"362","DOI":"10.2486\/indhealth.40.362","article-title":"Effects of pH and temperature on force and stiffness of skeletal muscle fibers during contraction and relaxation in relation to musculoskeletal disorders","volume":"40","author":"Ueno","year":"2002","journal-title":"Ind. Health"},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"1590","DOI":"10.1164\/ajrccm.155.5.9154862","article-title":"Effect of acute hypercapnia on diaphragmatic and limb muscle contractility","volume":"155","author":"Mador","year":"1997","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"1573","DOI":"10.1152\/jappl.1997.82.5.1573","article-title":"Respiratory muscle work compromises leg blood flow during maximal exercise","volume":"82","author":"Harms","year":"1997","journal-title":"J. Appl. Physiol."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"6321","DOI":"10.1113\/jphysiol.2012.242396","article-title":"Compensatory vasodilatation during hypoxic exercise: Mechanisms responsible for matching oxygen supply to demand","volume":"590","author":"Casey","year":"2012","journal-title":"J. Physiol."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"413","DOI":"10.1016\/j.mehy.2009.09.051","article-title":"Apnea: A new training method in sport?","volume":"74","author":"Joulia","year":"2010","journal-title":"Med. Hypotheses"},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"1460","DOI":"10.1152\/japplphysiol.00221.2003","article-title":"Spleen volume and blood flow response to repeated breath-hold apneas","volume":"95","author":"Valic","year":"2003","journal-title":"J. Appl. Physiol."},{"key":"ref_83","doi-asserted-by":"crossref","unstructured":"Bahensk\u00fd, P., Bunc, V., Tlust\u00fd, P., and Grosicki, G.J. (2020). Effect of an eleven-day altitude training program on aerobic and anaerobic performance in adolescent runners. Medicina, 56.","DOI":"10.3390\/medicina56040184"},{"key":"ref_84","first-page":"243","article-title":"Effects of voluntary hypoventilation on blood gases and acid\u2013base balance during exercise","volume":"103","author":"Woorons","year":"2008","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_85","first-page":"59","article-title":"Influence of different voluntary hypoventilation techniques on tolerance to high-intensity exercise","volume":"29","author":"Woorons","year":"2008","journal-title":"Int. J. Sports Med."},{"key":"ref_86","first-page":"372","article-title":"Running performance and respiratory variables in hypoventilation training","volume":"98","author":"Prieur","year":"2006","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1186\/s40798-025-00853-6","article-title":"Repeated-sprint training in hypoxia induced by voluntary hypoventilation at low lung volume: A meta-analysis","volume":"11","author":"Bouten","year":"2025","journal-title":"Sports Med. Open"},{"key":"ref_88","doi-asserted-by":"crossref","first-page":"714","DOI":"10.1016\/j.rmed.2005.07.013","article-title":"Tube breathing as a new potential method to perform respiratory muscle training: Safety in healthy volunteers","volume":"100","author":"Koppers","year":"2006","journal-title":"Respir. Med."},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1055\/s-2003-39084","article-title":"Ventilatory and metabolic response to rebreathing the expired air in the snorkel","volume":"24","author":"Toklu","year":"2003","journal-title":"Int. J. Sports Med."},{"key":"ref_90","doi-asserted-by":"crossref","unstructured":"Danek, N., Szczepan, S., Wr\u00f3blewska, Z., Michalik, K., and Zato\u0144, M. (2025). Hypercapnic warm-up and re-warm-up\u2014A novel experimental approach in swimming sprint. PLoS ONE, 20.","DOI":"10.1371\/journal.pone.0314089"},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"39916","DOI":"10.1038\/s41598-025-23633-4","article-title":"Validity of 2-point method for load-velocity profiling in free swimming, with snorkel, and with added respiratory dead space mask","volume":"15","author":"Szczepan","year":"2025","journal-title":"Sci. Rep."},{"key":"ref_92","doi-asserted-by":"crossref","unstructured":"Szczepan, S., Danek, N., Michalik, K., Wr\u00f3blewska, Z., and Zato\u0144, M. (2020). Influence of a six-week swimming training with added respiratory dead space on respiratory muscle strength and pulmonary function in recreational swimmers. Int. J. Environ. Res. Public Health, 17.","DOI":"10.3390\/ijerph17165743"},{"key":"ref_93","doi-asserted-by":"crossref","unstructured":"Hebisz, P., Hebisz, R., and Danek, N. (2025). Prolonging the warm-up effect by using additional respiratory dead space volume after the cessation of warm-up exercise. J. Clin. Med., 14.","DOI":"10.3390\/jcm14197049"}],"container-title":["Journal of Clinical Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/1\/364\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,5]],"date-time":"2026-01-05T11:13:05Z","timestamp":1767611585000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/1\/364"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,3]]},"references-count":93,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["jcm15010364"],"URL":"https:\/\/doi.org\/10.3390\/jcm15010364","relation":{},"ISSN":["2077-0383"],"issn-type":[{"value":"2077-0383","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,3]]}}}