[The effect of aging on the activity of the autonomic nervous system in long distance runners].

The aim of the study was to evaluate the effect of endurance physical training on the autonomic function in runners. The study was performed on 20 long distance runners, divided into two groups. The first group of runners contained 12 young men of age of 20-24 years (age 21.75 +/- 1.4 years: mean S.D.--standard deviation). Into the second group 9 experienced runners, who practice long distance running for over 40 years, were qualified. The mean age of those runners was 52.9 +/- 7.2 years. Moreover two control groups, matched for age and gender were recruited. One of them was made up of 12 healthy volunteers (age 21.6 +/- 1.23 years), the second contained 9 men (age 52.9 +/- 7.2 years). In this study, the measurement of the cardiac autonomic nervous system, using the HRV computer assisted programme (Proster, Poland), was performed. The characteristics of the HRV (heart rate variability) were estimated. We have observed, that the RR intervals in runners were longer than in healthy volunteers (1033.5 +/- 185.4 ms vs. 888.1 +/- 115.3 ms. p < 0.01). We have observed a tendency towards increasing of the RR intervals with the increase of age, of the tested person, as well. A reverse tendency, a shortening of the RR intervals with ageing, was observed in the control groups. The standard deviation of the RR intervals in runners was higher than in the control group (p < 0.05). In the young runners we noticed the prevalence of parasympathetic activity, expressed by the HF (high frequency) spectra (875.7 ms2 vs. 816.7 ms2) in comparison with the healthy individuals. In the old runners the prevalence of sympathetic activity, expressed by LF (low frequency) spectra (1088.75 ms2 vs. 220.1 ms2, p < 0.05) and parasympathetic activity (920.38 ms2 vs. 294.25 ms2) in comparison with the control group, was observed. It was expressed by the increase of the LF/HF ratio (0.75 vs. 2.1). The results of our study indicate, that the autonomic, particularly sympathetic, activity in sportsmen is not affected by ageing up to the sixth decade of life.