Dozens of soldiers at North Carolina's Fort Bragg suffered heat-related problems after participating in an early morning march.
Base spokesman Ben Abel said Friday that 37 soldiers required medical treatment. Of those, 13 were taken to Womack Army Medical Center.
One soldier remains in the hospital's intensive care unit.
About 60 soldiers from various units at the sprawling Army base in the southeastern area of the state set out at about 5:30 a.m. for a road march in full combat gear as part of final training to receive their expert field medical badge.
Temperatures were in the 70s but with a light rain and humidity as high as 95 percent.