European squads face sweltering North‑American venues as the 2026 World Cup kicks off. In a UK lab, Precision Fuel and Hydration reproduced Miami‑style conditions, recording a 0.64% body‑weight loss and a 1.55°C core rise in just 50 minutes of exercise. Modelling predicts about a quarter of matches will exceed 28°C WBGT, a level that FIFPRO deems unsafe.

Coaches have turned to science to blunt the heat’s impact. England’s Thomas Tuchel staged a West Palm Beach camp with 90°F drills, while Dutch boss Ronald Koeman warned that England’s squad selection favours low‑energy set pieces. Dr. Lindsey Hunt explains that rising skin temperature diverts blood from muscles, curbing high‑intensity runs and sprint repeats, especially in the second half.

The physiological toll translates into tangible results on the pitch. Scotland’s Ben Gannon‑Doak limped off after 75 minutes in a Boston night game, citing calf cramps. Experts estimate extreme heat can shave 20‑30% off performance, turning ordinary fatigue into dangerous cognitive lapses. Teams that arrive acclimated, manage recovery, and employ cooling tech will preserve more of their tactical edge.