title: The impact of prolonged exercise in a cold environment upon cardiac function.
abstract: OBJECTIVE
  The purpose of the present study was to examine the impact of cold exposure coupled with prolonged exercise upon postexercise left ventricular (LV) function and markers of myocardial damage.
  
  
  METHODS
  colon; Eight highly trained male athletes (mean +/- SD; age: 28.2 +/- 8.8 yr; height: 1.78 +/- 0.07 m; body mass: 74.9 +/- 7.6 kg; VO2max: 65.6 +/- 7.0 mL x kg(-1) x min(-1)) performed two 100-mile cycle trials, the first in an ambient temperature of 0 degrees C, the second in an ambient temperature of 19 degrees C. Echocardiographic assessment was completed and blood samples drawn before, immediately postexercise, and 24-h postexercise. Left ventricular systolic (stroke volume [SV], ejection fraction [EF], and systolic blood pressure/end systolic volume ratio [SBP/ESV]) and diastolic (early [E] to late [A] filling ratio [E:A]) parameters were calculated. Serum was analyzed for creatine kinase isoenzyme MB (CK-MBmass) and cardiac troponin T (cTnT). cTnT was analyzed descriptively whereas other variables were assessed using two-way repeated-measures ANOVA.
  
  
  RESULTS
  No significant change was observed in systolic function across time or between trials. A significant difference between trials was observed in E:A immediately after exercise (1.4 +/- 0.4 [19 degrees C] vs 1.8 +/- 0.3 [0 degrees C]) (P < 0.05). CK-MBmass was significantly elevated immediately after exercise in both trials (P < 0.05). Positive cTnT concentrations were observed in two subjects immediately after the 19 degrees C trial (0.012 microg x L(-1) and 0.034 microg x L(-1)).
  
  
  CONCLUSIONS
  Cycling 100 miles in an ambient temperature of 19 degrees C is associated with an acute change in diastolic filling that is not observed after prolonged exercise at 0 degrees C. Prolonged exercise is associated with minimal cardiac damage in some individuals; it appears that this is a separate phenomenon to the change in diastolic filling.
authors.affiliation: Department of Sport Sciences, Brunel University, Uxbridge, Middlesex, United Kingdom. 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: Myra
authors.initials: M
authors.lastname: Nimmo
authors.forename: Joseph
authors.initials: J
authors.lastname: Layden
authors.forename: Paul
authors.initials: P
authors.lastname: Collinson
authors.forename: David
authors.initials: D
authors.lastname: Gaze
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003080:Cold Temperature; D003402:Creatine Kinase / Q000097:blood; D052279:Creatine Kinase, MB Form; D004452:Echocardiography; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D008297:Male; D020107:Troponin T / Q000097:blood; D006113:United Kingdom; D016277:Ventricular Function, Left
chemical_list: D007527:Isoenzymes; D020107:Troponin T; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form