Key result
Inspiration beginning later than 450 ms before the subsequent heart beat accelerated the timing of the subsequent beat, whereas inspiration beginning sooner than 500 ms before had little effect.
Why the study?
Does the timing of respiratory events within the cardiac cycle modulate the heart rate response in humans?
Observational (n=14)
Does the timing of respiratory events within the cardiac cycle modulate the heart rate response in humans?
The timing of respiratory events in the cardiac cycle modulates respiratory sinus arrhythmia, highlighting the phase-sensitive nature of vagal control on heart rate.
May influence subsequent beat timing via respiratory phase; hypothesis-generating for phase-specific vagal mechanisms in cardiorespiratory research.
We asked whether the heart rate response to respiratory change varied as a function of timing within the cardiac cycle. Respiratory and electrocardiographic data were collected from seven men and seven women during three weekly sessions under conditions of normal and visually paced breathing. Results revealed that, when inspiration began sooner than 500 ms before the subsequent heart beat, inspiration had little effect on the subsequent interbeat interval. However, the timing of the subsequent beat was accelerated when inspiration began later than 450 ms before this heart beat. Similar relationships were observed for expiratory onset. Results were not attributable to volitional control or rate of breathing. The modulation of respiratory sinus arrhythmia by the timing of respiratory events in the cardiac cycle has implications for the role of vagal control in the synchronization of heart rate with respiratory and behavioral actions.
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Jennings et al. (1996) reported an observational. Timing of respiratory events within the cardiac cycle was evaluated on Heart rate response (interbeat interval) to respiratory change. Inspiration beginning later than 450 ms before the subsequent heart beat accelerated the timing of the subsequent beat, whereas inspiration beginning sooner than 500 ms before had little effect.
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