Cold water stimulation and its effect on heart rate variability: A short time fourier transform analysis

This study utilizes cold water consumption as a method of vagus nerve stimulation, investigating how body mass index (BMI) and repeated stimulation affect heart rate variability (HRV) in both time and frequency domains. HRV was measured in 18 subjects (mean age 21.3 ± 1.6 years) over 90 minutes, divided into three equal phases: resting (baseline), first stimulation (FSP), and second stimulation (SSP). Fourier and Short-Time Fourier Transform (STFT) analyses were used to extract the static and time-varying frequency components of HRV. For the normal body mass index (BMI) group, stimulation resulted in statistically significant changes in frequency band power densities compared to their baseline measurements (p