Introduction. Previous animal and human studies provided the evidence that testosterone may affect ventricular repolarization by shortening of the QT interval. Synthetic derivatives of testosterone, modified to enhance its anabolic properties, are occasionally abused by some competitive athletes. Objective. We assessed whether the QT interval duration could discriminate androgenic anabolic steroids (AAS)-using strength athletes (SA) from drug-free endurance athletes (EA), by comparing 25 formulas for QT interval correction. Methods. We recruited 22 elite male athletes involved in long-term strength or endurance training and 20 sedentary controls. All elite