I drank only pure water during my runs at 95°F: the day I ended up dizzy after a session, I understood what my sweat had been draining away for weeks
A runner collapsed with dizziness after weeks of hydrating with pure water during 95°F sessions—only to discover their sweat had been silently draining away essential electrolytes. Plain water alone isn’t enough during intense heat; your body needs sodium to maintain the delicate balance that keeps you upright.