Is your athlete already dehydrated before preseason practice even starts? For most, yes — about 76% are dehydrated in the morning and 66% stay that way all day. That costs roughly 8.3% of muscle endurance, 5.8% of power, and 5.5% of strength before the first whistle. Here's the simple fluid and sodium plan that fixes it, what to do on two-a-days, why cramping happens, and the lineman who added 90 pounds to his bench in five months.