Faculty Advisor

Kirsten Coffman

Area of Study

Science and Mathematics

Publication Date

Summer 2022


This study was conducted to better understand how cold water affects the mammalian dive reflex (MDR). Seven subjects volunteered to be immersed up to their shoulders in cold (17-20oC) and thermoneutral (37oC) water. Subjects performed 5 min of seated rest in air prior to water immersion and then 5 min of seated rest immersed in water, followed by five 40s apneas while immersed in water. Heart rate (HR) was collected during all phases. Exhaled O2 and CO2 were also collected at the end of each apnea as a marker of the drive to breathe. Cold water immersion lowered HR vs. thermoneutral water (Fig. 1, p=0.019), but did not significantly strengthen the fall in HR during apnea (Fig. 2). There were no significant differences in exhaled O2 and CO2 (Fig. 3). These results suggest that the MDR is strengthened by immersion in cold water, but not further augmented by apnea.


University of Puget Sound