Long-term high intensity sport practice modulates adaptative changes in athletes' heart and in the autonomic nervous system profile.

Background: The purpose of this study was to compare cardiovascular and autonomic adaptation changes in athletes exposed to high intensity and uninterrupted training for extended periods of time.
Methods: We assessed hemodynamic profile and cardiac function in 22 international master-level athletes free of cardiovascular disease who experienced particularly intensive and uninterrupted training over an 8- to 21-year-period.
Results: One-way ANOVA revealed that in athletes, extreme and uninterrupted strength and endurance training over long periods of time (up to 21 years) causes an increase in resting heart rate (50.3±7.1 vs. 63.0±10.7, P=0.0429), diastolic (65.8±5.2 vs. 75.2±5.7, P=0.0222) and mean blood pressure (85.4±6.0 vs. 95.6±6.4, P=0.0166). On multiple regression, increasing training experience was related to decrease in RRI (R2=0.18, P=0.0481) and increase in dBP (R2=0.32, P=0.0064) and mBP (R2=0.31, P=0.0075) although the effect was small. A negative correlation was observed between the training age and the parameters describing parasympathetic function: HF-RRI (R=-0.54, P=0.0321), HF-dBP (R=-0.52, P=0.0401) and PSD-RRI (R=-0.51, P=0.0414).
Conclusions: Long-term sport practice at a world class level causes an increase in resting heart rate, diastolic and mean blood pressure, and decrease of the parasympathetic dominance and this may result from decreasing adjustment to large training loads.