Modelling complex sports adaptation with electrocardiography: analysis of standard ECG, heart rate variability and QRST integral changes in elite athletes

Abstract Background Basic resting electrocardiographic changes caused by regular intense exercise are known characteristics of the athlete’s heart. Through detailed analysis of short-term ECG recordings, our aim was to study electrocardiographic, heart rate variability, and ventricular heterogeneity changes of the athlete’s heart as a function of factors influencing sports adaptation. Methods Analysis of 1-minute resting lead I ECG recordings was used to determine standard ECG parameters, time-domain indicators of heart rate variability, and mean and standard deviation of QRST integrals. Statistical analysis was performed in Python development environment. Results 500 healthy athletes (age: 19[16–24]y, male: 55%, training: 16.7 ± 6.5 h/w) were compared with 100 non-athlete controls (age: 21[17–23]y, male: 51%). Athletes had lower heart rate (68[61–78]vs.82[73–91]BPM, p < 0.001), increased p-wave amplitude (89[71–108]vs.80[62–96]µV, p < 0.001), PQ interval (152[140–168]vs.142[132–152]ms, p < 0.001), QRS width (90[82–100]vs.82[78–90]ms, p < 0.001), T-wave amplitude (257[198–311]vs.195[146–248]µV, p < 0.001), SDNN (64.7[47.2–87.2]vs.50.6[36.5–66.3]ms, p < 0.001), RMSSD (52.6[34.8–78.3]vs.36.4[26.8–52.6]ms, p < 0.001), pNN50 (31.1[12.7–50.9]vs.14.7[4.9–31.6]%, p < 0.001) and mean QRST integral (34.9[28.3–43.4]vs.26.1[19.7–33.9]mV*ms, p < 0.001) compared to controls. Mixed athletes had wider QRS compared to power athletes (94[90–102]vs.88[84–96]ms, p < 0.005). Male athletes had lower QTc, increased PQ interval, QRS width, T-wave amplitude, mean QRST integral, and its deviation. In the control group, females had higher resting heart rate and QTc duration, while AVNN and the relative deviation of QRST integral were lower. Many of the above parameters also showed weak correlation with age and weekly exercise hours. Conclusions Our findings indicate that a 1-minute lead I ECG recording can detect electrical differences between athletes and non-athlete controls and may provide a practical framework for future longitudinal studies of athletic cardiac adaptation.