{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T16:07:39Z","timestamp":1787155659501,"version":"build-2736575974"},"reference-count":34,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2024,7,30]],"date-time":"2024-07-30T00:00:00Z","timestamp":1722297600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Physiol."],"abstract":"<jats:sec><jats:title>Purpose<\/jats:title><jats:p>To compare acute physiological responses and perceived training stress between one long and two short time- and intensity-matched sessions of moderate-intensity training in endurance athletes.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Fourteen male endurance athletes (VO<jats:sub>2max<\/jats:sub>: 69.2 \u00b1 4.2\u00a0mL\u00b7min<jats:sup>\u22121<\/jats:sup>\u00b7kg<jats:sup>\u22121<\/jats:sup>) performed one 6 \u00d7 10-min interval session (SINGLE) and two 3 \u00d7 10-min interval sessions interspersed with 6.5\u00a0h recovery (DOUBLE) of moderate-intensity training on two separate days, while running in the laboratory, using a counterbalanced cross-over trial. The two training days were separated into a first part\/session (interval stage 1\u20133) and second part\/session (interval stage 4\u20136). Respiratory variables, heart rate (HR), blood lactate concentrations (BLa), and rating of perceived exertion (RPE) were collected during sessions, whereas supine heart rate (HR) was assessed in a 60-min recovery period following sessions. Measures of perceived training stress (1\u201310) were assessed in the morning of the subsequent day.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>HR, Bla, and RPE increased in the second compared to first part of SINGLE (168 \u00b1 7 vs. 173 \u00b1 7\u00a0bpm, 2.60 \u00b1 0.75 vs. 3.01 \u00b1 0.81\u00a0mmol\u00b7L<jats:sup>\u22121<\/jats:sup>, and 13.4 \u00b1 1.0 vs. 14.8 \u00b1 1.1-point, respectively, all <jats:italic>p<\/jats:italic> &amp;lt; 0.05). HR and Bla decreased in the second compared to first session of DOUBLE (171 \u00b1 9 vs. 166 \u00b1 9\u00a0bpm and 2.72 \u00b1 0.96 vs. 2.14 \u00b1 0.65\u00a0mmol\u00b7L<jats:sup>\u22121<\/jats:sup>, respectively, both <jats:italic>p<\/jats:italic> &amp;lt; 0.05). SINGLE revealed higher supine HR in the recovery period following sessions (65.4 \u00b1 2.5 vs. 60.7 \u00b1 2.5\u00a0bpm <jats:italic>p<\/jats:italic> &amp;lt; 0.05), session RPE (sRPE, 7.0 \u00b1 1.0 vs. 6.0 \u00b1 1.3-point, <jats:italic>p<\/jats:italic> = .001) and sRPE training load (929 \u00b1 112 vs. 743 \u00b1 98, <jats:italic>p<\/jats:italic> &amp;lt; 0.001) compared to DOUBLE. In the subsequent morning, increased levels of perceived fatigue and muscle soreness were observed following SINGLE compared to DOUBLE (7.0 \u00b1 2.5 vs. 8.0 \u00b1 1.0-point, <jats:italic>p<\/jats:italic> = .049 and 6.0 \u00b1 2.5 vs. 7.0 \u00b1 2.5-point, <jats:italic>p<\/jats:italic> = .002, respectively).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>One long moderate-intensity training session was associated with a duration-dependent \u201cdrift\u201d in physiological responses compared to two short time- and intensity-matched sessions, thereby suggesting a higher overall training stimulus. Simultaneously, the lower cost of the two shorter sessions indicates that such organization could allow more accumulated time at this intensity. Overall, these findings serve as a starting point to better understand the pros and cons of organizing moderate-intensity training as one long versus shorter sessions performed more frequently (e.g., as \u201cdouble threshold training\u201d) in endurance athletes.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fphys.2024.1428536","type":"journal-article","created":{"date-parts":[[2024,7,30]],"date-time":"2024-07-30T04:40:42Z","timestamp":1722314442000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":6,"title":["Comparison of acute physiological responses between one long and two short sessions of moderate-intensity training in endurance athletes"],"prefix":"10.3389","volume":"15","author":[{"given":"Rune","family":"Kj\u00f8sen Talsnes","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Per-\u00d8yvind","family":"Torvik","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Knut","family":"Skovereng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"\u00d8yvind","family":"Sandbakk","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2024,7,30]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"292","DOI":"10.2165\/00007256-199621040-00005","article-title":"Circadian Variation in Sports Performance","volume":"21","author":"Atkinson","year":"1996","journal-title":"Sports Med."},{"key":"B2","volume-title":"The Norwegian Model of Lactate Threshold Training and Lactate Controlled Approach to Training","author":"Bakken","year":"2022"},{"key":"B3","doi-asserted-by":"publisher","first-page":"3","DOI":"10.1080\/17461391.2014.920926","article-title":"Carbohydrate Availability and Exercise Training Adaptation: Too Much of a Good Thing?","volume":"15","author":"Bartlett","year":"2015","journal-title":"Eur. J. Sport Sci."},{"key":"B4","doi-asserted-by":"publisher","first-page":"92","DOI":"10.2340\/1650197719702239298","article-title":"Perceived Exertion as an Indicator of Somatic Stress","volume":"2","author":"Borg","year":"1970","journal-title":"Scand. J. Rehabil. Med."},{"key":"B5","doi-asserted-by":"publisher","first-page":"1032","DOI":"10.1249\/mss.0000000000002869","article-title":"Polarized Training Is Not Optimal for Endurance Athletes","volume":"54","author":"Burnley","year":"2022","journal-title":"Med. Sci. Sports Exerc"},{"key":"B6","doi-asserted-by":"publisher","first-page":"3782","DOI":"10.3390\/ijerph20053782","article-title":"Does Lactate-Guided Threshold Interval Training within a High-Volume Low-Intensity Approach Represent the \u201cNext Step\u201d in the Evolution of Distance Running Training?","volume":"20","author":"Casado","year":"2023","journal-title":"Int. J. Environ. Res. Public Health"},{"key":"B7","doi-asserted-by":"publisher","first-page":"1984","DOI":"10.1519\/JSC.0b013e31825770a7","article-title":"The Effect of Training at a Specific Time of day: A Review","volume":"26","author":"Chtourou","year":"2012","journal-title":"J. Strength Cond. Res."},{"key":"B8","doi-asserted-by":"publisher","first-page":"594","DOI":"10.1249\/01.mss.0000121982.14718.2a","article-title":"Heart Rate Variability During Exercise Performed Below and Above Ventilatory Threshold","volume":"36","author":"Cottin","year":"2004","journal-title":"Med. Sci. Sports Exerc"},{"key":"B9","doi-asserted-by":"publisher","first-page":"S139","DOI":"10.1007\/s40279-014-0253-z","article-title":"Monitoring Training Load to Understand Fatigue in Athletes","volume":"44","author":"Halson","year":"2014","journal-title":"Sports Med."},{"key":"B10","doi-asserted-by":"publisher","first-page":"46","DOI":"10.1186\/s40798-022-00438-7","article-title":"The Training Characteristics of World-Class Distance Runners: An Integration of Scientific Literature and Results-Proven Practice","volume":"8","author":"Haugen","year":"2022","journal-title":"Sports Med. Open"},{"key":"B11","doi-asserted-by":"publisher","first-page":"408","DOI":"10.1111\/sms.12673","article-title":"Prolonged Constant Load Cycling Exercise is Associated With Reduced Gross Efficiency and Increased Muscle Oxygen Uptake","volume":"27","author":"Hopker","year":"2017","journal-title":"Scand. J. Med. Sci. Sports"},{"key":"B12","doi-asserted-by":"publisher","first-page":"3","DOI":"10.1249\/MSS.0b013e31818cb278","article-title":"Progressive Statistics for Studies in Sports Medicine and Exercise Science","volume":"41","author":"Hopkins","year":"2009","journal-title":"Med. Sci. Sports. Exerc."},{"key":"B13","doi-asserted-by":"publisher","first-page":"35","DOI":"10.1113\/jphysiol.2007.143834","article-title":"Endurance Exercise Performance: The Physiology of Champions","volume":"586","author":"Joyner","year":"2008","journal-title":"J. Physiol."},{"key":"B14","doi-asserted-by":"publisher","first-page":"38","DOI":"10.55860\/NBXV4075","article-title":"The Norwegian Double-Threshold Method in Distance Running: Systematic Literature Review","volume":"3","author":"Kelemen","year":"2023","journal-title":"Sci. J. Sport Perform."},{"key":"B15","doi-asserted-by":"publisher","first-page":"677","DOI":"10.1123\/ijspp.8.6.677","article-title":"Preconditioning Strategies to Enhance Physical Performance on the Day of Competition","volume":"8","author":"Kilduff","year":"2013","journal-title":"Int. J. Sports Physiol. Perform."},{"key":"B16","doi-asserted-by":"publisher","first-page":"863","DOI":"10.3389\/fpsyg.2013.00863","article-title":"Calculating and Reporting Effect Sizes to Facilitate Cumulative Science: A Practical Primer for t-tests and ANOVAs","volume":"4","author":"Lakens","year":"2013","journal-title":"Front. Psychol."},{"key":"B17","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1111\/j.1600-0838.2010.01184.x","article-title":"Training for Intense Exercise Performance: High-Intensity or High-Volume Training? Scand","volume":"20","author":"Laursen","year":"2010","journal-title":"J. Med. Sci. Sports"},{"key":"B18","doi-asserted-by":"publisher","first-page":"53","DOI":"10.2165\/00007256-200232010-00003","article-title":"The scientific Basis for High-Intensity Interval Training: Optimising Training Programmes and Maximising Performance in Highly Trained Endurance Athletes","volume":"32","author":"Laursen","year":"2002","journal-title":"Sports Med."},{"key":"B19","doi-asserted-by":"publisher","first-page":"1619","DOI":"10.1007\/s40279-021-01459-0","article-title":"The Importance of \u201cDurability\u201d in the Physiological Profiling of Endurance Athletes","volume":"51","author":"Maunder","year":"2021","journal-title":"Sports Med."},{"key":"B20","doi-asserted-by":"publisher","first-page":"709","DOI":"10.1249\/MSS.0b013e31890eb86","article-title":"American College of Sports Medicine Position Stand. Nutrition and Athletic Performance","volume":"41","author":"Rodriguez","year":"2009","journal-title":"Med. Sci. Sports Exerc"},{"key":"B21","doi-asserted-by":"publisher","first-page":"250","DOI":"10.1111\/j.1600-0838.2009.01035.x","article-title":"Strength Training Improves 5-Min All-Out Performance Following 185 Min Of Cycling","volume":"21","author":"R\u00f8nnestad","year":"2011","journal-title":"Scand. J. Med. Sci. Sports"},{"key":"B22","doi-asserted-by":"publisher","first-page":"885","DOI":"10.1123\/ijspp.2023-0131","article-title":"The Evolution of World-Class Endurance Training: The Scientist\u2019s View on Current and Future Trends","volume":"18","author":"Sandbakk","year":"2023","journal-title":"Int. J. Sports Physiol. Perform."},{"key":"B23","doi-asserted-by":"publisher","first-page":"276","DOI":"10.1123\/ijspp.5.3.276","article-title":"What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes?","volume":"5","author":"Seiler","year":"2010","journal-title":"Int. J. Sports Physiol. Perform."},{"key":"B24","doi-asserted-by":"publisher","first-page":"1366","DOI":"10.1249\/mss.0b013e318060f17d","article-title":"Autonomic recovery After Exercise in Trained Athletes: Intensity and Duration Effects","volume":"39","author":"Seiler","year":"2007","journal-title":"Med. Sci. Sports Exerc"},{"key":"B25","doi-asserted-by":"publisher","first-page":"1102","DOI":"10.1080\/17461391.2022.2111276","article-title":"Development and validity of the subjective training quality scale","volume":"23","author":"Shell","year":"2023","journal-title":"Eur. J. Sport Sci."},{"key":"B26","doi-asserted-by":"publisher","first-page":"2283","DOI":"10.1007\/s40279-022-01680-5","article-title":"Decoupling of Internal and External Workload During a Marathon: An Analysis of Durability in 82,303 Recreational Runners","volume":"52","author":"Smyth","year":"2022","journal-title":"Sports Med."},{"key":"B27","doi-asserted-by":"publisher","first-page":"120109","DOI":"10.1016\/j.lfs.2021.120109","article-title":"A new perspective on cardiovascular drift during prolonged exercise","volume":"287","author":"Souissi","year":"2021","journal-title":"Life Sci."},{"key":"B28","doi-asserted-by":"publisher","first-page":"1258585","DOI":"10.3389\/fspor.2023.1258585","article-title":"The Proportional Distribution of Training by Elite Endurance Athletes at different Intensities During Different Phases of the Season","volume":"5","author":"Sperlich","year":"2023","journal-title":"Front. Sports Act. Living"},{"key":"B29","doi-asserted-by":"publisher","first-page":"1595","DOI":"10.1007\/s40279-023-01850-z","article-title":"Long-Term Development of Training Characteristics and Performance-Determining Factors in Elite\/International and World-Class Endurance Athletes: A Scoping Review","volume":"53","author":"Staff","year":"2023","journal-title":"Sports Med."},{"key":"B30","doi-asserted-by":"publisher","first-page":"295","DOI":"10.3389\/fphys.2015.00295","article-title":"The training intensity Distribution Among Well-Trained and Elite Endurance Athletes","volume":"6","author":"St\u00f6ggl","year":"2015","journal-title":"Front. Physiol."},{"key":"B31","doi-asserted-by":"publisher","first-page":"1590","DOI":"10.1123\/ijspp.2022-0212","article-title":"One Long Versus 2 Short Sessions? Physiological and Perceptual Responses to Low-Intensity Training at Self-Selected Speeds in Cross-Country Skiers","volume":"17","author":"Talsnes","year":"2022","journal-title":"Int. J. Sports Physiol. Perform."},{"key":"B32","doi-asserted-by":"publisher","first-page":"e0256662","DOI":"10.1371\/journal.pone.0256662","article-title":"Laboratory- and field-Based Performance-Predictions in Cross-Country Skiing And Roller-Skiing","volume":"16","author":"Talsnes","year":"2021","journal-title":"PLoS One"},{"key":"B33","doi-asserted-by":"publisher","first-page":"S287","DOI":"10.1123\/ijspp.2016-0404","article-title":"Prediction of Functional Overreaching From Subjective Fatigue and Readiness to Train After Only 3 Days of Cycling","volume":"12","author":"Ten Haaf","year":"2017","journal-title":"Int. J. Sports Physiol. Perform."},{"key":"B34","doi-asserted-by":"publisher","first-page":"694","DOI":"10.1177\/1747954119872321","article-title":"Three Norwegian Brothers all European 1500 m Champions: What is the Secret?","volume":"14","author":"Tjelta","year":"2019","journal-title":"Int. J. Sports Sci. Coach."}],"container-title":["Frontiers in Physiology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fphys.2024.1428536\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,7,30]],"date-time":"2024-07-30T04:40:47Z","timestamp":1722314447000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fphys.2024.1428536\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,7,30]]},"references-count":34,"alternative-id":["10.3389\/fphys.2024.1428536"],"URL":"https:\/\/doi.org\/10.3389\/fphys.2024.1428536","relation":{},"ISSN":["1664-042X"],"issn-type":[{"value":"1664-042X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,7,30]]},"article-number":"1428536"}}