Like any type of physical exertion, running is going to make you sweat. The volume of liquid you lose will depend on the distance and difficulty of your course, how hard you push yourself, environmental factors like temperature, and a variety of other influences.
What you can be sure of is that you're going to sweat. When this happens, your blood volume is going to wane. What does this mean?
It means your heart has to work harder to transport blood, oxygen, and nutrients throughout your body. It also means your muscles and other tissues may not be receiving the nutrients needed to recover from the stresses of high-intensity exercise. You may feel fatigue, pain, and more severe symptoms during and after your run, and it could take longer to recover.
In other words, you want to stay hydrated in order to see the best results and exercise in a safe and responsible manner. Here are a few basics to ensure that you maintain adequate hydration when you run.
Before, During, and After
If you reach the end of your run feeling like your mouth is full of sand, there's a good chance you haven't hydrated properly, and you're probably going to chug water until you feel sick. Why wait and let it get to this point?
Trial and error is the best way to figure out how you like to hydrate when you run. Most people try to drink a couple of glasses of water in the hour or two before a run. If you're running for an hour or less, you probably don't need to carry water with you, but if you're running longer, you should definitely bring water or plan courses with water stops along the way (such as parks with drinking fountains).
It's also a good idea to continue hydrating following your run, especially with runs of several miles. Your body will probably keep sweating for a while afterward, and you want to make sure that you're getting the essential nutrients needed for recovery following your run.
How Much to Hydrate
This is a question every runner wrestles with, and the problem is that there's no simple answer. Several factors will determine the amount of hydration you need, and while you can plan to hydrate before, during, and after your run, to some extent you're going to have to play it by ear.
If you think about a marathon or other long race, you'll probably find that water stations are set up every 2-3 miles, depending on the race. This is a good rule of thumb to follow when determining how often to hydrate during training.
A bit of trial and error should give you clues as to how often to hydrate, but your body is the ultimate gauge. If you start to feel thirsty, drink some water. If you're not sure if you're drinking enough, take a look at your urine. When your body is properly hydrated, urine will be pale yellow, rather than a darker yellow or orange hue.
What the Heck Are Electrolytes?
Electrolytes are substances like sodium, potassium, magnesium, and calcium that our bodies need to function properly. We lose them through sweat and they cannot be replenished by drinking water alone. In fact, without sodium, water is likely to pass right through the body without adequately hydrating.
If you're running several miles, then you need to replenish your electrolytes. Sports drinks, gels, and so on usually contain electrolytes, but you should try them out before a big race to figure out which products you prefer and how much you can tolerate. Too much of these products could make you feel sick, so you should always intersperse them with water consumption.
Carrying Water with You
Serious runners are naturally concerned with speed, and carrying water and sports drinks can slow you down. That said, dehydration can also be extremely detrimental to performance. What's the solution?
There are several options for carrying water, such as sport belts that distribute water around the waist thanks to spaces that hold small bottles. You can also find flasks that strap to the wrist. However, many distance runners prefer a backpack with a bladder and a hose that comes over the shoulder for easy sipping. The right gear can make a real difference in terms of both hydration and comfort.