It sounds so simple to hear that hydration is an important ingredient in achieving superior running performance. When you run, you sweat. When you sweat, you lose fluids. When you lose fluids, your blood flow volume decreases. When your blood flow volume decreases, your heart has to work harder to deliver oxygen to your working muscles. If you hydrate properly, you replenish lost fluids resulting in an increase in blood flow, improvements in heart performance and greater supply of oxygen to working muscles.
There is a note of caution though; drinking too much during training can cause GI issues (at the very least, you will have to go pee often). If you drink WAY TOO MUCH water, there is also a chance you will get hyponatremia. This condition occurs because electrolytes that are essential (notably sodium) are diluted to dangerously low levels resulting in “water intoxication.”
Drinking plain water is fine, but I generally tend to drink sports drinks to replace the sodium and electrolytes lost because of sweating. Sports drinks also provide a slight boost in energy via carbs and sometimes caffeine! I don’t have a particular drink of choice but lately I have been consuming nuun Active or Gatorade Endurance Hydration. nuun Active is packed with electrolytes and tastes really good. It doesn’t have any sugar and comes in refreshing light flavors making it quite a perfect drink. Gatorade Endurance Hydration on the other hand comes as either a drink or a gel. It comes packed with electrolytes and carbs for both replenishment and renewed energy. I generally use nuun on shorter sessions and Gatorade on longer sessions.
Moral of the story: Drink plenty of nuun and Gatorade while training and during races (this is especially true of races lasting more than an hour).
As for my own training today, i ran quick fartleks on the treadmill at The Village today. It was only a 45-minute run for a total of 5.55 miles but it felt smooth and easy.