Clinical Question: Is there evidence to support precooling with cold water immersion prior to endurance cycling and running in hot, humid environments to enhance performance? Clinical Bottom Line: There is moderate evidence suggesting cold water immersion (CWI) as a precooling intervention improves endurance performance in cyclists and runners in a hot, humid environment. All five included studies reported significant improvements in endurance performance regarding time to exhaustion or distance traveled. In all included studies, core temperature was significantly decreased in the CWI group versus the control group during the fifth and twentieth minutes of exercise. No significant differences were reported for the rating of perceived exertion (RPE) between the CWI and control groups.