CALIBRATING INTENSITY Soldiers take part in a road march during Ranger assessment at Fort Benning, GA. The “precision medicine” approach based on an individual’s documented physiological responses could be particularly useful in high-intensity Ranger training where march and run paces are adjusted for environmental conditions. Pacing currently is based on estimates of environmental effects but could be based on individual data in the future. (U.S. Army photo by SGT William E. Henry, Indiana National Guard Public Affairs)