{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,27]],"date-time":"2026-07-27T19:39:49Z","timestamp":1785181189819,"version":"3.55.0"},"reference-count":36,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2025,7,31]],"date-time":"2025-07-31T00:00:00Z","timestamp":1753920000000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:sec>\n               <jats:title>Objectives<\/jats:title>\n               <jats:p>This study examines the effects of a 4-week high-intensity interval training (HIIT) program on energy metabolism and maximal oxygen uptake (VO<jats:sub>2<\/jats:sub>max) in elite swimmers, aiming to provide empirical evidence for optimizing competitive swimming training.<\/jats:p>\n            <\/jats:sec>\n            <jats:sec>\n               <jats:title>Methods<\/jats:title>\n               <jats:p>Twenty-four competitive swimmers were randomly assigned to either an HIIT experimental group or a control group. The experimental group underwent a structured 4-week lower-limb HIIT program, while the control group continued their regular training regimen. Energy metabolism parameters and VO<jats:sub>2<\/jats:sub>max were assessed using a Lode lower-limb power cycle and a gas metabolism analyzer. Repeated measures analysis was used to examine interaction effects, with data analysis conducted at a significance level of <jats:italic>P<\/jats:italic>\u00a0&lt;\u00a00.05.<\/jats:p>\n            <\/jats:sec>\n            <jats:sec>\n               <jats:title>Results<\/jats:title>\n               <jats:p>The HIIT group exhibited significant improvements in all energy metabolism parameters and VO<jats:sub>2<\/jats:sub>max. Phosphagen energy supply increased from 40.39\u00a0\u00b1\u00a09.46 kJ to 58.27\u00a0\u00b1\u00a09.12 kJ (<jats:italic>P<\/jats:italic>\u00a0&lt;\u00a00.001), glycolytic energy supply increased from 41.81\u00a0\u00b1\u00a09.81 kJ to 59.06\u00a0\u00b1\u00a010.86 kJ (<jats:italic>P<\/jats:italic>\u00a0&lt;\u00a00.001), and aerobic energy supply increased from 132.29\u00a0\u00b1\u00a025.12 kJ to 173.32\u00a0\u00b1\u00a029.50 kJ (<jats:italic>P<\/jats:italic>\u00a0&lt;\u00a00.001). Consequently, total energy supply rose from 214.48\u00a0\u00b1\u00a038.58 kJ to 290.65\u00a0\u00b1\u00a042.01 kJ (<jats:italic>P<\/jats:italic>\u00a0&lt;\u00a00.001). Additionally, VO<jats:sub>2<\/jats:sub>max significantly improved from 51.48\u00a0\u00b1\u00a03.85 ml\/min\/kg to 55.03\u00a0\u00b1\u00a04.90 ml\/min\/kg (<jats:italic>P<\/jats:italic>\u00a0=\u00a00.041), whereas no significant changes were observed in the control group.<\/jats:p>\n            <\/jats:sec>\n            <jats:sec>\n               <jats:title>Conclusion<\/jats:title>\n               <jats:p>The findings confirm that a 4-week lower-limb HIIT program significantly enhances energy metabolism and VO<jats:sub>2<\/jats:sub>max in elite swimmers. These results underscore the efficacy of HIIT in improving metabolic adaptability, thereby supporting its application as a key training strategy for optimizing competitive swimming performance.<\/jats:p>\n            <\/jats:sec>","DOI":"10.7717\/peerj.19788","type":"journal-article","created":{"date-parts":[[2025,7,31]],"date-time":"2025-07-31T08:44:32Z","timestamp":1753951472000},"page":"e19788","source":"Crossref","is-referenced-by-count":4,"title":["Influence of 4-week lower extremity high-intensity interval training on energy metabolism and maximal oxygen uptake of elite swimmers"],"prefix":"10.7717","volume":"13","author":[{"given":"Rangxi","family":"Jin","sequence":"first","affiliation":[{"name":"School of Athletic Performance, Shanghai University of Sport, Shanghai, Shanghai, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Junhui","family":"Sun","sequence":"additional","affiliation":[{"name":"School of Athletic Performance, Shanghai University of Sport, 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