{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,20]],"date-time":"2026-10-20T06:53:48Z","timestamp":1792479228673,"version":"4.5.0"},"reference-count":29,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,12,4]],"date-time":"2025-12-04T00:00:00Z","timestamp":1764806400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Fulbright Scholarship"},{"DOI":"10.13039\/100003231","name":"PADI Foundation","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100003231","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JFMK"],"abstract":"<jats:p>Background: Physiological and psychological factors are important for determining static breath-hold duration. Preconditioning, such as preparatory apneas at functional residual capacity, is a potentially valuable method for prolonging breath-hold duration at total lung capacity. We investigated the physiological influence of preparatory apneas to determine the possible association with maximal apnea duration via diaphragmatic pressure and electromyographic measurements. Methods: Fourteen male breath-hold divers (39 \u00b1 10 years; body mass, 87.2 \u00b1 8.5 kg; body fat, 14.4 \u00b1 3.8%; body height, 186.6 \u00b1 3.9 cm; training experience, 14.2 \u00b1 9.6 years) were included. We measured diaphragm activity during breath-holds via transdiaphragmatic pressure (Pdia) using balloon-tipped catheters in the stomach and esophagus and electromyographic (EMG) activity. From these, \u2206EMG and \u2206Pdia for every involuntary breathing movement (IBM) during all apneas were quantified. Furthermore, a pressure difference (difference between the first and last IBM Pdia value) and the respiratory neuromuscular output index (RNMI) (\u2206Pdia\/\u2206EMG) were included as indirect parameters of the pressure perceived. These variables were measured during three preparatory breath-holds (average duration = 185 \u00b1 69 s and range = 62\u2013309 s, separated by 2.5 min) and three maximal breath-holds (average duration = 308 s and range = 179\u2013733 s, separated by 5 min). Results: The preparatory apnea performed at FRC elicited significantly higher Pdia activity (p &lt; 0.00) and a significantly lower RNMI (p = 0.00\u20130.01) compared to the maximal apneas. Furthermore, a higher and more pronounced increase in Pdia during the preparatory apnea at FRC was related to longer maximal apneas (Max 1, r = 0.65, p = 0.01; Max 2, r = 0.65, p = 0.02; Max 3, r = 0.66, p = 0.01). Conclusions: The results suggest an acute preconditioning effect of primarily the preparatory apnea at FRC on the duration of the subsequent maximal apneas. The implementation of preparatory apneas preceding maximal apneas during training sessions may elicit a longer breath-hold duration in trained divers.<\/jats:p>","DOI":"10.3390\/jfmk10040471","type":"journal-article","created":{"date-parts":[[2025,12,4]],"date-time":"2025-12-04T16:07:38Z","timestamp":1764864458000},"page":"471","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Dynamics of Preparatory Apneas and Their Influence on Maximal Dry Static Apnea in Breath-Hold Divers"],"prefix":"10.3390","volume":"10","author":[{"given":"Dario","family":"Vrdoljak","sequence":"first","affiliation":[{"name":"Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan Campus, Kelowna, BC V1V 1V7, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-0421-982X","authenticated-orcid":false,"given":"Colin D.","family":"Hubbard","sequence":"additional","affiliation":[{"name":"Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Geoff B.","family":"Coombs","sequence":"additional","affiliation":[{"name":"School of Psychology and Sport Science, Bangor University, Bangor LL57 2DG, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7826-4290","authenticated-orcid":false,"given":"Andrew T.","family":"Lovering","sequence":"additional","affiliation":[{"name":"Department of Human Physiology, University of Oregon, Eugene, OR 97403, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ivan","family":"Drvis","sequence":"additional","affiliation":[{"name":"Faculty of Kinesiology, University of Zagreb, 10000 Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nikola","family":"Foretic","sequence":"additional","affiliation":[{"name":"Faculty of Kinesiology, University of Split, 21000 Split, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joseph W.","family":"Duke","sequence":"additional","affiliation":[{"name":"Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u017deljko","family":"Duji\u0107","sequence":"additional","affiliation":[{"name":"Department of Integrative Physiology, University of Split School of Medicine, 21000 Split, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Patrician, A., Duji\u0107, \u017d., Spaji\u0107, B., Drvi\u0161, I., and Ainslie, P.N. (2021). Breath-Hold Diving-The Physiology of Diving Deep and Returning. Front. Physiol., 12.","DOI":"10.3389\/fphys.2021.639377"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"635","DOI":"10.1113\/EP086269","article-title":"Physiology of static breath holding in elite apneists","volume":"103","author":"Bain","year":"2018","journal-title":"Exp. Physiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1214","DOI":"10.1249\/MSS.0b013e31820a4e0c","article-title":"Breath-hold diving: Respiratory function on the longer term","volume":"43","author":"Walterspacher","year":"2011","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"429","DOI":"10.1113\/jphysiol.1986.sp016196","article-title":"The diving response in man: Effects on sympathetic activity in muscle and skin nerve fascicles","volume":"377","author":"Fagius","year":"1986","journal-title":"J. Physiol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1871","DOI":"10.1152\/jappl.1986.60.6.1871","article-title":"Cardiac performance in humans during breath holding","volume":"60","author":"Ferrigno","year":"1986","journal-title":"J. Appl. Physiol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1840","DOI":"10.1152\/japplphysiol.00334.2009","article-title":"Involuntary breathing movements improve cerebral oxygenation during apnea struggle phase in elite divers","volume":"107","author":"Dujic","year":"2009","journal-title":"J. Appl. Physiol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s00421-008-0771-1","article-title":"Heart rate and blood pressure time courses during prolonged dry apnoea in breath-hold divers","volume":"104","author":"Perini","year":"2008","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"197","DOI":"10.2478\/v10078-012-0036-2","article-title":"The role of training in the development of adaptive mechanisms in freedivers","volume":"32","author":"Ostrowski","year":"2012","journal-title":"J. Hum. Kinet."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"228","DOI":"10.1016\/j.resp.2012.03.007","article-title":"The influence of varying inspired fractions of O2 and CO2 on the development of involuntary breathing movements during maximal apnoea","volume":"181","author":"Breskovic","year":"2012","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"174","DOI":"10.1016\/j.resp.2008.01.008","article-title":"Restoration of hemodynamics in apnea struggle phase in association with involuntary breathing movements","volume":"161","author":"Palada","year":"2008","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"382","DOI":"10.1113\/EP091346","article-title":"Respiratory system responses to a maximal apnoea","volume":"110","author":"Hubbard","year":"2024","journal-title":"Exp. Physiol."},{"key":"ref_12","first-page":"11","article-title":"Predicting performance in competitive apnea diving, part II: Dynamic apnoea","volume":"40","author":"Schagatay","year":"2010","journal-title":"Diving. Hyperb Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1235","DOI":"10.1152\/japplphysiol.00256.2025","article-title":"Reduction in respiratory muscle strength following a series of preparatory and maximal static, dry breath-holds","volume":"139","author":"Hubbard","year":"2025","journal-title":"J. Appl. Physiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1016\/S0954-6111(99)90150-6","article-title":"Assessment of respiratory function: Influence of spirometry reference values and normality criteria selection","volume":"93","author":"Quadrelli","year":"1999","journal-title":"Respir. Med."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1324","DOI":"10.1183\/09031936.00080312","article-title":"Multi-ethnic reference values for spirometry for the 3\u201395-yr age range: The global lung function 2012 equations","volume":"40","author":"Quanjer","year":"2012","journal-title":"Eur. Respir. J."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"513","DOI":"10.1164\/ajrccm.160.2.9808067","article-title":"Functional magnetic stimulation of the abdominal muscles in humans","volume":"160","author":"Polkey","year":"1999","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1554","DOI":"10.1152\/japplphysiol.01389.2005","article-title":"Exercise-induced abdominal muscle fatigue in healthy humans","volume":"100","author":"Taylor","year":"2006","journal-title":"J. Appl. Physiol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"238","DOI":"10.1186\/s13054-018-2172-0","article-title":"Estimation of the diaphragm neuromuscular efficiency index in mechanically ventilated critically ill patients","volume":"22","author":"Jansen","year":"2018","journal-title":"Crit. Care"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"944","DOI":"10.1111\/j.1440-1681.2005.04289.x","article-title":"Effect of human splenic contraction on variation in circulating blood cell counts","volume":"32","author":"Palada","year":"2005","journal-title":"Clin. Exp. Pharmacol. Physiol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1152\/jappl.1974.37.3.291","article-title":"Physiological and conventional breath-hold breaking points","volume":"37","author":"Lin","year":"1974","journal-title":"J. Appl. Physiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1016\/0034-5687(88)90002-3","article-title":"Similarities between behavior of respiratory muscles in breath-holding and in elastic loading","volume":"72","author":"Whitelaw","year":"1988","journal-title":"Respir. Physiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1249\/MSS.0b013e3182690e6a","article-title":"Respiratory muscle pressure development during breath holding in apnea divers","volume":"45","author":"Cross","year":"2013","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/j.resp.2015.11.017","article-title":"Dynamic diaphragmatic MRI during apnea struggle phase in breath-hold divers","volume":"222","author":"Batinic","year":"2016","journal-title":"Respir. Physiol. Neurobiol."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Binder, M.D., Hirokawa, N., and Windhorst, U. (2009). Electromyography. Encyclopedia of Neuroscience, Springer.","DOI":"10.1007\/978-3-540-29678-2"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1256","DOI":"10.1152\/jappl.1997.83.4.1256","article-title":"Human respiratory muscle actions and control during exercise","volume":"83","author":"Aliverti","year":"1997","journal-title":"J. Appl. Physiol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"719","DOI":"10.1161\/HYPERTENSIONAHA.108.127530","article-title":"Cardiovascular regulation during apnea in elite divers","volume":"53","author":"Heusser","year":"2009","journal-title":"Hypertension"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"4825","DOI":"10.1113\/jphysiol.2010.195941","article-title":"Sympathetic neural activation: An ordered affair","volume":"588","author":"Steinback","year":"2010","journal-title":"J. Physiol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1695","DOI":"10.1113\/EP091938","article-title":"Reference values for respiratory muscle strength measured with the S-Index Test in well-trained athletes, e-sports athletes and age-matched controls","volume":"110","author":"Kowalski","year":"2025","journal-title":"Exp. Physiol."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Mi\u0161i\u0107, N.\u017d., Ostoji\u0107, M., Cvetkovi\u0107, S., Miodragovi\u0107, P., Ani\u010di\u0107, Z., Kova\u010di\u0107 Popovi\u0107, A., and Stefanovi\u0107, \u0110. (2023). Wavelet Analysis of Respiratory Muscle sEMG Signals during the Physiological Breakpoint of Static Dry End-Expiratory Breath-Holding in Naive Apneists: A Pilot Study. Sensors, 23.","DOI":"10.20944\/preprints202305.2160.v1"}],"container-title":["Journal of Functional Morphology and Kinesiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2411-5142\/10\/4\/471\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,6]],"date-time":"2025-12-06T05:14:01Z","timestamp":1764998041000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2411-5142\/10\/4\/471"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,4]]},"references-count":29,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2025,12]]}},"alternative-id":["jfmk10040471"],"URL":"https:\/\/doi.org\/10.3390\/jfmk10040471","relation":{},"ISSN":["2411-5142"],"issn-type":[{"value":"2411-5142","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,12,4]]}}}