SPECTRAL-ANALYSIS OF HEART-RATE-VARIABILITY IN ATHLETES

The objectives of the study were to characterize power spectrum patter n of the heart rate variability and assessment of the relative contrib utions of sympathetic and parasympathetic cardiac nervous system contr ol in athletes. Thirty-three male athletes, swimming (1), canoeing (10 ), cycling (6), athletics (4), football (3), roller-skating (2) and vo lleyball (7) aged 23.4+/-5.5 years, with a mean athletic level of 18 h ours/week (8-45) and 33 sedentary healthy control subjects were includ ed. Ecg signals were recorded after a period of 15 minutes in supine r est with controlled breathing at 15 cycles/min. Signal acquisition was done at 300 samples/sec. From 512 consecutive heart beats, we calcula ted mean average, standard deviation, maximum and minimum R-R interval s and, after computing the fast Fourier transform, total spectrum powe r, low frequency (LF), high frequency (HF) components and its ratio (L F/HF). The average R-R interval was 987.7+/-168.8 ms and 762.7+/-125.3 ms, the variance was 5.44 and 2.51 ms2 and ratio of R-R interval maxi mum/minimum (E/I ratio) 1.53+/-0.16 and 1.41+/-0.16, respectively for athletes and control group. Differences between groups were significan t (p<0.01) for all parameters, with higher variability in the athletes . Both spectral bands (LF and HF) had higher power in athletes (LF=925 +/-920 and HF=2258+/-2349 ms2) than in the control group (LF=442+/-446 and HF=1179+/-1542 ms2)(p<0.01). There were no significant difference s for LF/HF ratio, or normalized LF (LF%) or normalized HF (HF%) betwe en groups. The present results indicates higher power of both spectral bands (LF and HF) and higher amplitude of the respective peaks in ath eletes when compared with healthy sedentary which suggests that higher heart rate variability observed in athletes is due to increased paras ympathetic activity.