The effect of different types of sports on resting heart rate variability and autonomic nervous system balance

Abstract

Heart rate variability (HRV) refers to the beat-to-beat variation in heart rate, largely due to fluctuating influences of the autonomic nervous system. There are indications that active participation in sport can alter the resting HRV and autonomic nervous system balance. The aim of this preliminary study was to determine whether different sports have different effects on autonomic balance, and whether HRV differs when top performers from their respective fields are compared. HRV measured in a control group and three groups of elite South African athletes were compared: endurance athletes, field hockey players and skydivers. Time domain, frequency domain and Poincaré analyses of baseline HRV were used to determine whether a difference exists between the three groups. Results were compared by means of a Kruskal-Wallis one way analysis of variance statistical test. This study indicated statistically significant differences between elite athletes from different sport types and a control group with regard to HRV and resting autonomic regulation of cardiac function. Of the three groups the endurance athletes had the highest HRV, as well as the highest vagal tone. The skydivers recorded the lowest HRV with sympathetic nervous system dominance. The control group and hockey players showed intermediate values between the other two groups for all parameters. Different types of sports influence resting autonomic balance to different extents. The results of this study point towards higher fitness levels, in terms of autonomic control of cardiac function in participants involved in aerobic-demanding sports activities. Lower HRV and increased sympathetic CV influence in the skydiving group may indicate increased dysrhythmogenic risk. Further studies conducted during non-participating periods and also in the later, post- participation years are recommended.