Abstract
The autonomic nervous system (ANS) has an important role in physical performance.
However, the cardiac ANS activity in high-level track and field athletes has been
poorly explored. Thus, we tested the hypothesis that endurance and power athletes
would present a markedly different cardiac autonomic control at rest. We analyzed
the cardiac ANS by means of time and frequency domains heart rate variability (HRV)
analyses and by symbolic analysis. Endurance athletes showed higher pulse interval
than power athletes (1 265±126 vs. 1 031±98 ms respectively; p<0.05). No differences
were found in time and frequency domains between the groups. However, the LF%, HF%
and LF/HF ratio presented high effect sizes (1.46, 1.46 and 1.30, respectively). The
symbolic analysis revealed that endurance athletes had higher 2V parasympathetic modulation
(36±6.5) than power athletes (24±9.3; p<0.05). A reduced 0V sympathetic modulation
was observed in endurance athletes (21±9.9) compared to power athletes (33±11; p<0.05
and ES=1.30). Our results suggest greater parasympathetic modulation and less sympathetic
modulation in endurance athletes compared to power athletes. Additionally, the type
of HRV analysis needs to be chosen with well-defined criteria and caution because
their use in assessing cardiac autonomic modulation can interfere with the interpretation
of results. In practical terms, symbolic analysis appears to better discriminate between
cardiac autonomic activities of athletes with different training backgrounds than
frequency domain analysis.
Key words
autonomic nervous system - heart rate - athletes - sports - exercise - athletic performance
