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.
