Habituation to the Cold Pressor Test

Abstract

During acute cold exposure, a stress response is induced. PURPOSE: The purpose of this study was to see if daily, cold water exposure to the dominant hand causes habituation to the stress responses that occur due to cold exposure. METHODS: Fourteen seemingly healthy men (age=22± 2 years, height=70± 3cm, body fat %= 17.5± 12.9%) participated in the study. Subjects performed the cold pressor test (CPT) a total of 20 times for 4 weeks (5 times per week). Data was collected during the first and final day of the 20-day habituation period. Blood glucose levels were measured before and immediately after the CPT. Subjects were asked to respond to both pain and thermal sensation scale every 30 seconds during the CPT testing. RESULTS: A repeated measures ANOVA showed a significant main effect for time for glucose, day 1 versus the final day (F=5.16; p=.04). A paired T-test also revealed a significant difference between the changes in glucose levels (pre-CPT-post-CPT), day 1 versus the final day (mean difference=11.79; t-ratio=2.27; p=.02). The mean change pre to post CPT in glucose on day one was 12±13 mmol/L, and the mean change in glucose on the final day was .5±18 mmol/L. Repeated measures ANOVA showed a significant main effect for time for pain scale, but there was no significant main effect for time for thermal sensations (pain scale: F=27.39; p=.01) (thermal sensation: F=.68; p=.72). Pain scale responses decreased significantly while thermal sensations remained unaltered. The average pain scale response on day one was 5±5, and on the final day 1±1. CONCLUSION: This study found a significantly decreased glucose response after 20 days of cold water exposure to the hand. This demonstrates habituation to the stress response. The perception of pain decreased significantly, but not thermal discomfort. More studies are needed to further the investigation on the physiological processes that habituated due to repeated cold exposure.