Study of the Effect of Short-Time Cold Stress on Heart Rate Variability

摘要

The present work focuses on whether the heart rate variability (HRV) evaluated during the cold stress is different from that in the control condition. In fifteen subjects (12M & 3F, aging 21~24 yrs), a five-minute ECG record was performed in the room temperature condition (27°C), and the other five-minute ECG record was then measured in the cold stress during which an ice bag was placed on the forehead. After the R-R intervals were extracted from these two 5-minute ECG recording signals, we analyzed them using the time- and frequency-domain techniques. The results showed a significant decrease in PNN50 defined as the count of two continuous R-R intervals larger than 50 ms divided by the total number (control 25.4±20.9 versus cold stress 19.8±18.3 %, p < 0.05). In addition, there was a significant difference in the power in the high frequency range of 0.15 ~ 0.4 Hz (control 14.63±7.38 versus cold stress 12.03±5.14 ms~2, p < 0.05). Thus, as the human body encounters a short-term cold stress exposure, only a 5-minute HRV analysis can also demonstrate a significant reduction in the parasympathetic nervous activity.