The rising temperatures are affecting marathon runners' safety and performance, with risks of heat exhaustion and heatstroke becoming more prevalent (Chicago Tribune, 2026-08-23). In the U.S. Sun Belt, 92% of runners using the Runna coaching app have adapted or skipped runs due to hot weather. The physiological stress of training in extreme heat is significant, requiring runners to adjust their pace and training schedules. Race organizers are also making changes, such as rescheduling events or offering alternative options for participants, to mitigate risks. However, the increasing frequency of extreme weather events may deter some runners from participating in outdoor races altogether.