Just Cool It

They continued to study Cao for the next six weeks. If they applied cooling between sets, Cao’s performance held steady in set after set. Without cooling, it decayed. “It was as if he had no fatigue,” Heller recalls. “We saw incredible gains over the next six weeks. He tripled his capacity to 620 pull-ups.” Preventing muscle exhaustion allowed Cao to train harder, leading to rapid gains in muscle strength. Heller and Grahn theorize that more blood, and thus, oxygen, is available to the muscles when the body doesn’t have to route extra blood to the radiators for cooling.