Effects of half ironman competition on the development of late potentials.
OBJECTIVE
The primary purpose was to evaluate the prevalence of late potentials (LPs) in triathletes before and after a half ironman triathlon. The secondary purpose was to examine whether LPs are the electrocardiographic expression of a greater myocardial mass.


METHODS
Nine asymptomatic male triathletes (mean age +/- SD, 32 +/- 5 yr) were examined using signal-averaged ECG (SAECG) 48-72 h before (PRE), immediately after (POST), and 24-48 h after the completion (RECOVERY) of a half ironman triathlon. Late potentials were considered to be present if two of the following SAECG anomalies were observed: 1) a prolonged filtered QRS (/QRS) complex (> or = 114 ms), 2) a lengthened low amplitude signal (LAS) duration (>38 ms), and/or 3) a low root mean square (RMS) voltage of the last 40 ms of the fQRS (<20 microV). Left ventricular dimensions were determined at PRE using M-mode echocardiography.


RESULTS
There were no significant differences between PRE, POST, and RECOVERY in the fQRS duration, the LAS duration, or the RMS voltage. Two athletes displayed a single SAECG abnormality during PRE and two SAECG anomalies (i.e., LPs) during POST. Late potentials remained in one of the two athletes during RECOVERY. A moderate relationship existed between fQRS and left ventricular mass (r = 0.67, P < 0.05).


CONCLUSIONS
Ultra-endurance training and/or events do not lead to LPs in the majority of triathletes who do not possess ventricular arrhythmias. However, a small subset of triathletes do display SAECG anomalies, which are augmented by an ultra-endurance event and may persist even after recovery from the event. Left ventricular mass does not affect overall SAECG parameters.
Warburton DER
Faculty of Physical Education and Recreation, and Division of Cardiology, University of Alberta, Edmonton, Canada. dew1@gpu.srv.ualberta.ca
Welsh
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Haykowsky
M J
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Taylor
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Humen
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Dzavik
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D000328:Adult; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D004562:Electrocardiography; D006339:Heart Rate; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D016277:Ventricular Function, Left