Effects of the cold face test on heart rate variability in students

Abstract

The purpose of this study was to determine the effects of the cold pressor test on heart rate variability in students. Sixty five students with a mean age of 20.61±0.13 years take part in the study (86% women, 14% men). They were studied in the morning hours in a quiet room at a comfortable temperature. Time domain (SDNN, RMSSD, pNN50), frequency domain (TP, HF, VLF, LF and LF/HF ratio) and nonlinear (SD1, SD2, ApEn, SampEn, D2, DFA1, DFA2) parameters of HRV were obtained from all participants for 5 minutes before and 5 minutes during cold face test (0–1 °C cold compresses) in a supine position. Statistical analysis was performed using Mann-Whitney test. Heart rate during cold face test was significantly lower than that during rest period (74.03±1.26 vs 76.74±1.21 beat/min, p=0.006). Time domain parameters were found to be higher during cold face test than that during rest (SDNN: 52.6±2.85 vs 43,61±2,23 ms, p=0.006; RMSSD: 59.87±4.08 vs 44.99±2.93 ms, p=0.001 and pNN50: 30.49±2.38 vs 22.07±2.13 %, p=0.003). There was no differences during cold face test period and rest period in TP (2517.24±301.8 vs 2097.89±249.98 ms2, p=0.456; VLF: 92.44±12.21 vs 83.59±9.99 ms2, p=0.452; LF: 1024.98±132.06 vs 932.86±107.70 ms2, p=0.896. High frequency parameter was significantly higher during cold face test than that during rest (1395.36±184.39 vs 1078.11±143.13 ms2, p=0.013). Nonlinear measures were significantly higher during cold face test than that during rest (SD1: 42.39±2.89 vs 31.83±2.07 ms, p=0.001; SD2: 60.52±3.04 vs 52.45±2.50 ms, p=0.025). ApEn and D1 were significantly lower during cold face test than that during rest (respectively, 1.15±0.01 vs 1.40±0.01 and 0.87±0.03 vs 1.01±0.02, p<0.001). The other HRV parameters including D2, LF/HF ratio, pLF, pHF, SampEn, DFA2 were not significantly different. These results suggest that cold face test has been associated with increased vagal cardiac control and decrease entropy and D1.