title: Changes in naïve and memory T-cells in elite swimmers during a winter training season.
abstract: High intensity training regimens appear to put athletes at a higher risk of illness. As these have been linked to alterations in the proportions of differentiated T cells, how training load affects these populations could have important implications for athlete susceptibility to disease. This study examined the effect of a winter training season on the proportions of circulating naïve and memory T cells subsets of high competitive level swimmers. Blood samples were taken at rest at 4 time-points during the season: before the start of the season (t0-September), after 7weeks of an initial period of gradually increasing training load (t1-November), after 6weeks of an intense training cycle (t2-February) and 48h after the main competition (t3-April) and from eleven non-athlete controls at 2 similar time-points (t2 and t3). CD4, CD8 and gamma-delta (γδ) T cells expressing the naïve (CCR7(+)CD45RA(+)), central-memory (CM-CCR7(+)CD45RA(-)), effector-memory (EM-CCR7(-)CD45RA(-)) and terminal effector (TEMRA-CCR7(-)CD45RA(+)) were quantified by flow cytometry. Statistical analyses were performed using multilevel modeling regression. Both T CD4(+) naïve and CM presented a linear increase in response to the first moment of training exposure, and had an exponential decrease until the end of the training exposure. As for TCD4(+) EM, changes were observed from t2 until the end of the training season with an exponential trend, while TCD4(+) TEMRA increased linearly throughout the season. TCD8(+) naïve increased at t1 and decreased exponentially thereafter. TCD8(+) TEMRA values decreased at t1 and increased exponentially until t3. γδT-EM had an increase at t1 and an exponential decrease afterwards. In contrast, γδT-TEMRA decreased at t1 and exponentially increased during the remaining 20weeks of training. An increase in TEMRA and EM T cells alongside a decrease in naïve T cells could leave athletes more susceptible to illness in response to variation in training stimulus during the season.
authors.affiliation: Research Center for Sport and Physical Activity, Faculty of Sport Sciences and Physical Education, Coimbra University, Portugal. Electronic address: ateixeira@fcdef.uc.pt.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Teixeira
authors.affiliation: Research Center for Sport and Physical Activity, Faculty of Sport Sciences and Physical Education, Coimbra University, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Rama
authors.affiliation: Research Center for Sport and Physical Activity, Faculty of Sport Sciences and Physical Education, Coimbra University, Portugal.
authors.forename: Humberto M
authors.initials: HM
authors.lastname: Carvalho
authors.affiliation: Research Center for Sport and Physical Activity, Faculty of Sport Sciences and Physical Education, Coimbra University, Portugal.
authors.forename: Grasiely
authors.initials: G
authors.lastname: Borges
authors.affiliation: Portuguese Institute for Blood and Transplantation, Coimbra, Portugal.
authors.forename: Tiago
authors.initials: T
authors.lastname: Carvalheiro
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Gleeson
authors.affiliation: CIPER, Faculty of Human Kinetics, University of Lisbon, Portugal.
authors.forename: Francisco
authors.initials: F
authors.lastname: Alves
authors.affiliation: Portuguese Institute for Blood and Transplantation, Coimbra, Portugal.
authors.forename: Hélder
authors.initials: H
authors.lastname: Trindade
authors.affiliation: Portuguese Institute for Blood and Transplantation, Coimbra, Portugal.
authors.forename: Artur
authors.initials: A
authors.lastname: Paiva
mesh_terms: D000293:Adolescent; D000328:Adult; D056352:Athletes; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005260:Female; D006801:Humans; D007156:Immunologic Memory; D008297:Male; D013550:Swimming / Q000502:physiology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D055815:Young Adult
keywords: CCR7; CD45RA; Exercise; Training load; γδ T cells