title: Decrease in QRS amplitude in juvenile female competitive athletes during the initial twenty-one months of intensive training.
abstract: BACKGROUND
  The aim of this project was to study changes in QRS amplitude in junior female athletes during the initial twenty-one months of competitive training programme in aerobic gymnastics.
  
  
  METHODS
  Somatometric parameters, heart rate (HR), blood pressure (BP) and 12-lead ECGs were recorded in 12 female athletes, aged 13-17 years (average 13.8) at 3-month intervals over a period of 21 months. The Sokolow-Lyon index (SLI) and the maximum QRS spatial vector magnitude (QRSmax), approximated from RV5, RaVF and SV2 voltages, were analyzed.
  
  
  RESULTS
  The mean values of QRSmax and SLI decreased gradually during the study period. The difference between the mean QRSmax values at the beginning and at the end of the study period was -0.8 mV (30.8%), p < 0.001, and between the initial and final values of SLI was -0.6 mV (24%), p < 0.001. The somatometric parameters changed only slightly, HR and systolic BP values did not change significantly.
  
  
  CONCLUSIONS
  This study showed that 21 months of competitive aerobic gymnastics training led to a decrease in the QRSmax magnitude. This finding is in contrast with the classical hypothesis on the ECG diagnostics of LVH and is in agreement with an alternative hypothesis on the relative voltage deficit during the early stage of LVH development. (Cardiol J 2007; 14: 260-265).
authors.forename: Ljuba
authors.initials: L
authors.lastname: Bacharova
authors.forename: Martina
authors.initials: M
authors.lastname: Tibenska
authors.forename: Dana
authors.initials: D
authors.lastname: Kucerova
authors.forename: Olga
authors.initials: O
authors.lastname: Kyselovicova
authors.forename: Helena
authors.initials: H
authors.lastname: Medekova
authors.forename: Jan
authors.initials: J
authors.lastname: Kyselovic