title: Seasonal changes in haematology, lymphocyte transferrin receptors and intracellular iron in Ironman triathletes and untrained men.
abstract: We investigated whether 12 months of chronic endurance training would affect haematology, CD4(+) lymphocyte transferrin receptor (CD71) expression, CD4(+) intracellular iron and the incidence of upper respiratory tract illnesses (URTI) in Ironman triathletes compared with untrained men. Resting venous blood samples were taken from 15 Ironman triathletes (TR 30 ± 5 year) and 12 untrained men (UT 30 ± 6 year) every 4 weeks for 12 months. Erythrocyte, leukocyte and platelet concentration, haematocrit, haemoglobin (Hb) and mean corpuscular haemoglobin (MCHC) were measured with a full blood count. CD4(+) lymphocytes were analysed for changes in transferrin receptor (CD71) expression (CD4(+)CD71(+)), and intracellular iron (Fe(3+)), by flow cytometry. The TR group had significantly lower Hb, MCHC, and platelets for 10, 9 and 11 months, respectively; lower CD4(+)CD71(+) (3 months) and Fe(3+) (1 month), respectively; higher CD4(+)CD71(+) (1 month); a higher lymphocyte count for 4 months. There were no between-group differences in other variables. In both groups haematology and lymphocytes increased during spring, early summer and winter and decreased during late summer/late winter, with an inverse relationship between CD4(+)CD71(+) and Fe(3+). The TR group reported significantly fewer URTI than the UT. Low Hb and MCHC suggest an iron deficiency which may affect triathlete performance. Monthly changes in lymphocytes, CD4(+)CD71(+) and Fe(3+) suggested that spring, summer and late autumn are associated with CD4(+) proliferation. There may be seasonal relationships between haematology and lymphocyte function, independent of endurance training, possibly affecting performance but not the incidence of URTI.
authors.affiliation: School of Sport and Exercise Science, Institute of Sport, Exercise and Active Living, Victoria University, PO Box 14428, Melbourne, VIC, 8001, Australia. suzanne.broadbent@vu.edu.au
authors.forename: Suzanne
authors.initials: S
authors.lastname: Broadbent
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000097:blood*; D056352:Athletes; D015704:CD4 Antigens / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism*; D007958:Leukocyte Count; D018655:Lymphocyte Count; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D011990:Receptors, Transferrin / Q000097:blood*; D012621:Seasons
chemical_list: D015703:Antigens, CD; D015704:CD4 Antigens; C068126:CD71 antigen; D006454:Hemoglobins; D011990:Receptors, Transferrin; D007501:Iron
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