title: Altered cardiac function and minimal cardiac damage during prolonged exercise.
abstract: OBJECTIVE
  The purpose of the present study was to examine markers of cardiac function and cardiac damage during a simulated half-ironman triathlon in highly trained athletes.
  
  
  METHODS
  Nine highly trained male triathletes volunteered for the study (mean +/- SD; age: 33 +/- 3 yr; height: 1.8 +/- 0.1 m; body mass: 77.7 +/- 3.2 kg). The subjects completed a half-ironman triathlon; 1.9-km swim in an indoor 20-m pool, followed by a laboratory-based 90-km cycle and 21.1-km run. Venous blood samples were drawn and echocardiographic assessment completed before the start of exercise, immediately after each stage, and 24 h postexercise. Serum was analyzed for total creatine kinase activity (CK), creatine kinase isoenzyme MB(mass) (CK-MB(mass)), and cardiac troponin T (cTnT). Left ventricular systolic (stroke volume, and systolic blood pressure/end systolic volume ratio (SBP/ESV)) and diastolic (ratio of early [E] to late [A], ventricular filling E:A) measurements were derived from echocardiographic assessment.
  
  
  RESULTS
  The mean completion time of the half-ironman triathlon was 301 +/- 28 min. Left ventricular contractility (SBP/ESV) was significantly reduced after the half-ironman triathlon (P < 0.05). A significant reduction in E:A was observed after the run phase of the half-ironman triathlon (P < 0.05). Significant increases in CK and CK-MB(mass) were observed during and after the half-ironman triathlon (P < 0.05), and cTnT was elevated in four subjects over the course of the half-ironman triathlon.
  
  
  CONCLUSIONS
  The physiologic stress imposed by the half-ironman triathlon resulted in a reduced left ventricular contractility and altered diastolic filling, coupled with minimal cardiac damage in a number of highly trained male triathletes. The mechanisms behind such altered cardiac function and cardiac damage after prolonged exercise are yet to be elucidated.
authors.affiliation: Department of Sport Sciences, Brunel University, Uxbridge, UK. rob.shave@brunel.ac.uk
authors.forename: Robert
authors.initials: R
authors.lastname: Shave
authors.forename: Ellen
authors.initials: E
authors.lastname: Dawson
authors.forename: Gregory
authors.initials: G
authors.lastname: Whyte
authors.forename: Keith
authors.initials: K
authors.lastname: George
authors.forename: David
authors.initials: D
authors.lastname: Gaze
authors.forename: Paul
authors.initials: P
authors.lastname: Collinson
mesh_terms: D000328:Adult; D001794:Blood Pressure; D002302:Cardiac Output / Q000502:physiology*; D004562:Electrocardiography; D015444:Exercise; D006334:Heart Function Tests; D006801:Humans; D008297:Male; D012680:Sensitivity and Specificity; D019209:Troponin C / Q000032:analysis
chemical_list: D019209:Troponin C