Exercise-induced alterations of signal-averaged electrocardiograms in marathon runners

Am Heart J. 1989 Dec;118(6):1198-202. doi: 10.1016/0002-8703(89)90010-0.


Late potentials have been shown to predict malignant ventricular arrhythmias and sudden cardiac death. To determine whether prolonged, strenuous activity is associated with the development of ventricular late potentials, signal-averaged electrocardiography was performed on 30 marathon runners before, immediately after, and during a recovery period at least 1 week after they had a 26.2-mile race. The filtered QRS duration decreased immediately after the marathon to 94.4 +/- 10.0 msec from baseline values of 97.3 +/- 10.1 msec (p less than 0.005). Root mean square energy in the terminal 40 msec of the QRS complex increased immediately after the race from 60.4 +/- 35.6 uV to 71.0 +/- 41.7 uV (P less than 0.5). The duration of signals less than 40 uV in the terminal QRS were not appreciably altered. At the 1-week follow-up study, all parameters closely approximated the baseline values. No runner had a late potential after running the race. The one runner with a late potential at baseline had normal parameters immediately after the race. We conclude that signal-averaged ECG parameters are improved after a marathon is run, and the risk of an arrhythmic sudden death in adult runners without organic heart disease would seem to be low.

MeSH terms

  • Adult
  • Echocardiography
  • Echocardiography, Doppler
  • Electrocardiography*
  • Exercise / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Physical Endurance*
  • Running*