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Sweat Rate for Runners: How Much Do You Lose per Hour?
Runners lose about 1.3 liters of sweat per hour on average, but individual rates range from 0.2 to 5.0 liters. Calculate yours by weighing before and after a 60-minute run and adding back what you drank: every kilogram lost equals 1 liter of sweat. For runs over 60 minutes, drink between half and your full sweat rate, never more. Finishing heavier than you started warns of hyponatremia.
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