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Face immersion increases vagal activity as assessed by heart rate variability
N Hayashi1, M Ishihara, A Tanaka
1Faculty of Health and Sports Sciences, Osaka University Toyonaka, Japan.
Summary
Face immersion alone, a component of the diving reflex, enhances vagal activity. This was observed through increased heart rate variability, demonstrating a physiological response without breath-holding.
Area of Science:
- Physiology
- Cardiovascular Regulation
Background:
- The diving reflex is a complex physiological response to submersion.
- Vagal activity influences heart rate and is a key indicator of autonomic nervous system function.
Purpose of the Study:
- To investigate if face immersion alone, without breath-holding, can stimulate the diving reflex.
- To determine the effect of face immersion on vagal activity using heart rate variability.
Main Methods:
- Fifteen healthy men underwent trials involving face immersion in cold water (8-10°C) at various breathing frequencies.
- Electrocardiogram (ECG) for R-R intervals and gas exchange variables were recorded.
- Heart rate variability parameters (RRmean, SD[RR], CV[RR]) were analyzed.
Main Results:
- Face immersion significantly increased heart rate variability (SD[RR] and CV[RR]) and mean R-R interval (RRmean) at a breathing frequency of 20 breaths/min.
- No significant changes were observed in oxygen uptake or end-tidal partial pressures of O2 and CO2.
- Increased heart rate variability indicates enhanced vagal tone.
Conclusions:
- Face immersion alone, without breath-holding, is sufficient to increase vagal activity.
- This finding highlights the role of facial cold-water stimulation in modulating autonomic cardiovascular control.