{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T11:10:21Z","timestamp":1788952221574,"version":"build-2803163510"},"reference-count":30,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T00:00:00Z","timestamp":1788912000000},"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>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Sprint interval training (SIT) is widely used in competitive swimming, yet early post-exercise physiological and perceptual responses to different SIT configurations remain incompletely understood. This study compared in highly trained national-level middle- and long-distance swimmers. This study compared early post-exercise rating of perceived exertion (RPE), heart rate (HR), and blood lactate concentration (BLa) responses following four composite SIT configurations in national-level competitive middle- and long-distance freestyle swimmers.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Fifteen highly trained national-level swimmers participated in this randomized crossover study. Each participant completed four SIT configurations in randomized order, with a 7-day washout period between sessions: 12 \u00d7 25\u00a0m with 1-min recovery, 10 \u00d7 35\u00a0m with 80-s recovery, 8 \u00d7 50\u00a0m with 2-min recovery, and 6 \u00d7 75\u00a0m with 3-min recovery. The work-to-rest ratio was maintained at 1:4 across configurations. Rating of perceived exertion (RPE), heart rate (HR), and blood lactate concentration (BLa) were measured before exercise and immediately post-exercise and at 1, 3, 5, 7, and 9\u00a0min of recovery. Baseline-adjusted linear mixed-effects models were used to examine protocol, time, and protocol \u00d7 time effects, with post-exercise time treated as a categorical factor.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      After adjustment for session-specific baseline values, significant main effects of protocol and time were observed for RPE, HR, and BLa (all p &amp;lt; 0.001). The protocol \u00d7 time interaction did not reach statistical significance for RPE (p = 0.051) or HR (p = 0.209), A significant protocol \u00d7 time interaction was observed for BLa (p = 0.005). BLa remained lower after SIT-1 than after SIT-2, SIT-3, and SIT-4 throughout recovery and decreased from 14.47 mmol\u00b7L\n                      <jats:sup>-1<\/jats:sup>\n                      immediately post-exercise to 9.96 mmol\u00b7L\n                      <jats:sup>-1<\/jats:sup>\n                      at 9\u00a0min, whereas BLa remained comparatively elevated after SIT-2 and SIT-3.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Among the four composite configurations, SIT-1 (12 \u00d7 25\u00a0m) produced the lowest early-recovery BLa, whereas SIT-2 (10 \u00d7 35\u00a0m) elicited the highest overall RPE and HR and, together with SIT-3, maintained the highest BLa. Coaches should therefore select the complete SIT set structure according to the desired acute metabolic and perceptual load and subsequent within-session recovery requirements, rather than considering repetition distance alone.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fphys.2026.1922489","type":"journal-article","created":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T10:17:04Z","timestamp":1788949024000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Early post-exercise physiological and perceptual responses following different sprint interval training configurations in highly trained national-level swimmers: a randomized crossover study"],"prefix":"10.3389","volume":"17","author":[{"given":"Lijun","family":"Long","sequence":"first","affiliation":[{"name":"Sports Coaching College, Beijing Sport University","place":["Beijing, China"]},{"name":"Physical Education Institute, Hunan Normal University","place":["Changsha, Hunan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ke","family":"Chen","sequence":"additional","affiliation":[{"name":"Independent Researcher","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dongting","family":"Jiang","sequence":"additional","affiliation":[{"name":"School of Athletic Performance, Shanghai University of Sport","place":["Shanghai, China"]},{"name":"School of Coaching, Shanghai University of Sport","place":["Shanghai, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Meiling","family":"Tao","sequence":"additional","affiliation":[{"name":"School of Athletic Performance, Shanghai University of Sport","place":["Shanghai, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kejian","family":"Li","sequence":"additional","affiliation":[{"name":"School of Sport Training, Wuhan Sports University","place":["Wuhan, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pei","family":"Luo","sequence":"additional","affiliation":[{"name":"School of Sports Sciences, Beijing Sport University","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanqing","family":"Fu","sequence":"additional","affiliation":[{"name":"School of Education, Beijing Sport University","place":["Beijing, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hao-Nan","family":"Wang","sequence":"additional","affiliation":[{"name":"Sports Medicine Center, West China Hospital, Sichuan University","place":["Chengdu, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,9]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.3390\/app14052097","article-title":"Progression of sprint interval training set performance and physiological responses during a six-week training period","volume":"14","author":"Arsoniadis","year":"2024","journal-title":"Appl. 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