{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,7]],"date-time":"2025-11-07T09:53:06Z","timestamp":1762509186740,"version":"build-2065373602"},"reference-count":73,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2025,11,7]],"date-time":"2025-11-07T00:00:00Z","timestamp":1762473600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Research Center in Physical Activity, Health, and Leisure\u2014CIAFEL, Faculty of Sport, University of Porto"},{"name":"Portuguese Foundation for Science and Technology","award":["FCT UID\/00617\/2025"],"award-info":[{"award-number":["FCT UID\/00617\/2025"]}]},{"name":"The laboratory for Integrative and Translational Research in Population Health (ITR), Porto, Portugal","award":["la\/p\/oo64\/2020"],"award-info":[{"award-number":["la\/p\/oo64\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sports"],"abstract":"<jats:p>Background: Exercise-induced bronchoconstriction (EIB) is common in athletes, being more frequent in outdoor endurance-based\/long-distance sports. We followed a World-Class marathon paddler\u2019s season with recurrent episodes of EIB, which intensified during cold exposure workouts. This unique immunophenotype profile during the season and its variations were reflected in acute and chronic inflammatory markers. Methods: A longitudinal case study was conducted with blood sampling obtained from a single paddler after overnight fasting at three timepoints: T1 (beginning of season, after 15-day rest period), T2 (post-Winter National Championship), and T3 (post-Summer National Championship). Complete blood counts and lymphocyte immunophenotyping were performed using automated hematology analysis and multiparametric flow cytometry. Results: The total numbers of leukocytes (T1: 6.3; T2: 5.0; T3: 5.5 \u00d7 109\/L), neutrophils (3.1; 2.5; 2.8 \u00d7 109\/L), and lymphocytes (2.4; 1.8; 2.2 \u00d7 109\/L) declined between T1 and T2, followed by a partial recovery at T3. In contrast, monocyte counts exhibited the reverse pattern (0.41; 0.62; 0.31 \u00d7 109\/L). The two T cell subsets (\u03b1\u03b2 and \u03b3\u03b4) remained relatively stable, showing only minor seasonal fluctuations. CD19+ B cells, initially at very low levels, increased steadily as the season progressed (0.05; 0.07; 0.16 \u00d7 109\/L). During T2, the proportion of memory lymphocytes (CD45RO+) rose, while naive cells (CD45RA+) declined; this trend was subsequently inverted at M3. Although the CD4+\/CD8+ ratio varied over time, it consistently stayed below the normal reference range established for healthy controls (0.50; 0.83; 0.60 for T1, T2, and T3, respectively). Conclusions: The immune assessment of the World-Class marathon paddler revealed transient immunosuppression early in the season, marked by reduced neutrophils, a low CD4+\/CD8+ ratio, and diminished CD19+ lymphocytes. Over time, immune parameters showed signs of recovery, indicating a temporary imbalance that did not impair the athlete\u2019s physical performance. Conclusions: This case study of an elite marathon kayaker revealed transient immune fluctuations across a competitive season, including early immunosuppression (low neutrophils, CD4+\/CD8+ ratio 0.50, and minimal CD19+ B cells) followed by partial recovery mid- and late-season. Despite persistently inverted CD4+\/CD8+ ratios suggesting chronic immune dysregulation, the athlete maintained competitive performance, highlighting the temporary nature of these changes and emphasizing that regular immune monitoring can help optimize health and performance in elite athletes.<\/jats:p>","DOI":"10.3390\/sports13110401","type":"journal-article","created":{"date-parts":[[2025,11,7]],"date-time":"2025-11-07T09:14:45Z","timestamp":1762506885000},"page":"401","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Training, Immunity, and Health in Elite Kayaking: A Longitudinal Study Monitoring a World-Class Marathon Paddler with Exercise-Induced Bronchoconstriction"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6628-1410","authenticated-orcid":false,"given":"Jos\u00e9 Augusto Rodrigues","family":"dos Santos","sequence":"first","affiliation":[{"name":"Centre of Research, Education, Innovation and Intervention in Sport (CIFI<sub>2<\/sub>D), Faculty of Sports, University of Porto, 4200-450 Porto, Portugal"}]},{"given":"Tiago","family":"Rama","sequence":"additional","affiliation":[{"name":"Service of Immunoallergology, University Hospital Centre of S\u00e3o Jo\u00e3o, 4200-319 Porto, Portugal"},{"name":"Service of Basic and Clinical Immunology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal"}]},{"given":"Liliana Carina","family":"Baptista","sequence":"additional","affiliation":[{"name":"Faculty of Sport Sciences and Physical Education, University of Coimbra, 3040-248 Coimbra, Portugal"},{"name":"Interdisciplinary Center for the Study of Human Performance (CIPER-UC), Faculty of Sport Sciences and Physical Education, University of Coimbra, 3040-248 Coimbra, Portugal"}]},{"given":"Ana Isabel","family":"Padr\u00e3o","sequence":"additional","affiliation":[{"name":"Research Center in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sports, University of Porto (FADEUP), 4099-002 Porto, Portugal"},{"name":"Laboratory for Integrative and Translational Research in Population Health (ITR), 4050-600 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0494-0000","authenticated-orcid":false,"given":"Rodrigo","family":"Zacca","sequence":"additional","affiliation":[{"name":"Research Center in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sports, University of Porto (FADEUP), 4099-002 Porto, Portugal"},{"name":"Laboratory for Integrative and Translational Research in Population Health (ITR), 4050-600 Porto, Portugal"},{"name":"Nucleus of Research in Human Motricity Sciences, Universidad Adventista de Chile, Chill\u00e1n 3780000, Chile"},{"name":"Laboratory of Sport Physiology, Faculty of Sports, University of Porto, Rua Dr. Pl\u00e1cido da Costa 91, 4200-450 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"dos Santos, J.A.R., Boppre, G., and Zacca, R. 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