Purpose: The aim of the study was to explore a potential dose effect of water on heart rate responses and markers of vagal tone modulation.
Methods: This was a randomized crossover study involving eight men whose heart rate and heart rate variability parameters were continuously measured following ingestion of different volumes of still mineral water (200, 400, 600, and 800 mL).
Results: A significant volume by time effect for heart rate (p < 0.005) was observed. Ingestion of all volumes of drink water of more 200 mL significantly decreased the heart rate. Significant time effects for heart rate variability parameters were observed.
Conclusion: Ingestion of a mineral water drink affected the heart rate in men in a time-dependent manner, possibly by changes in cardiac vagal modulation.
Keywords: Cardiac; Heart rate variability; Natural product; Vagal modulation.