Tennis cramps are famous for a reason.
Everyone has watched a player seize up in a fifth set. It isn't bad luck or nerves — it's a hot, multi-hour match draining more sodium than changeover sips of water put back. The cramp builds quietly all match and lets go at the worst possible moment. Here's how to hydrate on the changeovers and dose sodium to your sweat, not the average.
Get your match number →Why the deciding set is when it hits.
A competitive match runs one to three-plus hours, often on a baking court, with a high sweat rate the whole time. Sweat sodium varies about tenfold between players, so a salty sweater can lose a large amount over a long match — far more than the water they sip between games. The deficit accumulates set by set and finally shows up as the full-body cramp in the third or fifth, when there's the least margin to recover. It's the clearest example in sport of a slow sodium leak with a dramatic ending.