Normative Values for QRS Duration in Athletes aged 12-35 years undergoing Pre-participation Exams

BACKGROUND: Due to limited data on athletic QRS duration, this cross-sectional study aims to establish normative digital reference values in asymptomatic, apparently healthy athletes ages 12 to 35 undergoing pre-participation examinations. OBJECTIVES: We hypothesized that QRS duration of athletes would be longer in males, increase with age, and rarely exceed 120 ms in the absence of a bundle branch block. METHODS: We analyzed QRS duration from standardized digital ECG recordings in 9,084 athletes (58% male, age 12-35 years, mean age 18) obtained during pre-participation examinations. Sex-stratified 99th-percentile quantile-regression equations were developed and applied in an APP to demonstrate that QRS duration outliers could be easily identified. RESULTS: Females had shorter QRS durations than males (88.5 +/- 8.3 ms vs. 97.3 +/- 9.1 ms; mean difference 8.9 ms, 95% CI: 8.5-9.2 ms). QRS duration demonstrated a positive cross-sectional association with age and was greater in men than women. Female 97.5 CONCLUSIONS: Our results indicate that defining prolonged QRS criteria necessitates adjustments according to age and sex. To facilitate future prospective research, we offer specific regression models to detect outliers.