Effects of half ironman competition on the development of late potentials

• Published in: Medicine and science in sports and exercise Vol. 32; no. 7; pp. 1208 - 1213
• Main Authors: WARBURTON, D. E. R, WELSH, R. C, HAYKOWSKY, M. J, TAYLOR, D. A, HUMEN, D. P, DZAVIK, V
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01-07-2000
• Subjects: Adult; Biological and medical sciences; Death, Sudden, Cardiac - etiology; Electrocardiography; Fundamental and applied biological sciences. Psychology; Heart Rate; Humans; Male; Myocardial Contraction - physiology; Physical Endurance - physiology; Space life sciences; Ventricular Function, Left; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Heart; Competition; Human; Electric potential; Late; Triathlon; Retarded potential; Electrophysiology; Athlete; Left ventricle; Sport; Electrocardiography; Circulatory system; Morphometry
• ISSN: 0195-9131; 1530-0315
• DOI: 10.1097/00005768-200007000-00004

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.
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.
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).
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.