Abstract:
The purpose of this investigation was to compare the heart rate variability at respiratory
frequency (HRVRF) in muscle contractions during the inspiratory phase with that during the expiratory
phase. Eight volunteers performed pedaling on a cycle ergometer, twice a cycle of
respiration (4 sec) against a load of 0.25 Nm/kg BW, of which the timing was adjusted
to twice during the inspiration phase (I), once during the expiration, once during
the inspiration (El), or twice during the expiration phase (E). Spectral analysis
was applied to the R-R intervals of each condition. The amplitude of HRVRF in E was less than half of I (9 ± 2 msec versus 23 ±2 msec). The results indicate
that the timing of muscle contraction can affect the heart rate variability even at
the frequency band of respiration.
Keywords:
Parasympathetic Nervous Activity - Respiratory Sinus Arrhythmia - Respiratory Phase
- Heart Rate Variability
