title: Prolonged exercise does not cause lymphocyte DNA damage or increased apoptosis in well-trained endurance athletes.
abstract: Recent research has demonstrated that lymphocyte apoptosis sensitivity appears to be related to training status and exercise intensity. This work investigated the effect of prolonged, submaximal treadmill running on percentage (%) apoptosis, % necrosis and DNA strand breaks in lymphocytes and related these to changes in total lymphocyte and blood cortisol concentrations in well-trained runners. Venous blood samples (n = 14) were taken immediately before (PRE), immediately after (IPE) and 3 h after (3PE) 2.5 h of treadmill running at 75% of VO2 max from eight well-trained male endurance athletes (age 34.2 +/- 2.44 years) and analysed for cellular content and serum cortisol concentrations. Lymphocytes were isolated from whole blood and % apoptotic and necrotic cell were detected by flow cytometry using Annexin V-FITC and propidium iodide uptake. DNA strand breaks were measured by single-cell gel electrophoresis. Despite a significant (P < 0.001) exercise-induced increase in mean serum cortisol concentrations and reduction in lymphocyte counts, the mean % Annexin-V positive cells (13.3 +/- 6.78 in PRE, 11.3 +/- 5.51 in IPE and 12.8 +/- 6.75 in 3PE samples) were not significantly different at the three time-points (P > 0.05). Mean DNA strand breaks in the lymphocytes also did not change significantly (P > 0.05) rising from 25.7 +/- 2.16 to 26.9 +/- 1.89 and 27.1 +/- 1.38 microm in IPE and 3PE samples, respectively. The exercise-induced changes in total blood lymphocyte counts and cortisol concentrations did not result in a significant change in % apoptotic lymphocytes or DNA strand breaks in the endurance-trained athletes during this prolonged, submaximal exercise.
authors.affiliation: School of Medical Sciences, Faculty of Health Sciences, University of KwaZulu-Natal, 519, Umbilo Road, Congella 4013, Private Bag 7, Durban, South Africa. futree@ukzn.ac.za
authors.forename: E M
authors.initials: EM
authors.lastname: Peters
authors.forename: M
authors.initials: M
authors.lastname: Van Eden
authors.forename: N
authors.initials: N
authors.lastname: Tyler
authors.forename: A
authors.initials: A
authors.lastname: Ramautar
authors.forename: A A
authors.initials: AA
authors.lastname: Chuturgoon
mesh_terms: D000328:Adult; D017209:Apoptosis / Q000502:physiology*; D002478:Cells, Cultured; D004249:DNA Damage / Q000502:physiology*; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D012420:Running / Q000502:physiology*