title: Are the relationships between early activation of lymphocytes and cortisol or testosterone influenced by intensified cycling training in men?
abstract: The effects of exercise training on lymphocyte responses, as well as changes in circulating endocrine parameters at rest, were investigated. Seven male cyclists participated in a 4 week high-intensity (HI) cycling training intervention. Training improved performance significantly (peak power output (PPO): 1.4%, p < 0.05; 5 km time trial: 3.8%, p < 0.01; 40 km time trial: 0.4%, p < 0.05). Resting hormone concentrations (testosterone, sex hormone binding globulin (SHBG), cortisol, corticosteroid-binding globulin (CBG), and dehydroepiandrosterone-sulphate (DHEA-S)) were unchanged, with the exception of a 20% decrease in testosterone post-HI training (p < 0.067). Subjects' CD3(+) cell counts decreased by 15% (p < 0.05), owing to significantly decreased CD4(+) cell counts and slightly lower CD8(+) and natural killer (NK) cell counts. Spontaneous in vitro CD69 expression increased in CD4(+) cells (mean +/- SD, pre: 12 +/- 6 cells x microL(-1); post: 35 +/- 37 cells x microL(-1); p < 0.05), but not in CD8(+) cells (pre: 20 +/- 29 cells x microL(-1); post: 33 +/- 16 cells x microL(-1)). Mitogen-induced CD69 expression decreased in both CD4+ (pre: 1570 +/- 1258 cells x microL(-1); post: 596 +/- 597 cells x microL(-1); p < 0.05) and CD8(+) lymphocytes (pre: 676 +/- 434 cells x microL(-1); post: 412 +/- 235 cells x microL(-1); p < 0.05). Testosterone correlated positively with several immune parameters at baseline, whereas cortisol correlated negatively with parameters of the innate immune system post-HI training. We conclude that the stress of unaccustomed exercise is evident in resting lymphocytes, but not in resting endocrine parameters. However, correlations between testosterone and cortisol and immune parameters suggest that these 2 hormones play a role in modulating immune status. Our results indicate the importance of assessing both spontaneous and mitogen-induced aspects of immune-cell activation.
authors.affiliation: Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa. csmith@sun.ac.za
authors.forename: Carine
authors.initials: C
authors.lastname: Smith
authors.forename: Kathryn H
authors.initials: KH
authors.lastname: Myburgh
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D006801:Humans; D006854:Hydrocortisone / Q000502:physiology*; D008213:Lymphocyte Activation / Q000502:physiology*; D008297:Male; D013739:Testosterone / Q000502:physiology*; D013997:Time Factors
chemical_list: D013739:Testosterone; D006854:Hydrocortisone