I see it happen all too often, athletes cramping on cool days, getting light headed or dizzy or developing headaches with no apparent reason (no hits to head, etc). I see it with my athletes at work. I see it in family and friends and I see it at races, and all too often it boils down to dehydration. It’s like no one drinks water anymore. I know everyone seems to carry a water bottle, but they don’t seem to use it often enough.
It’s not just my opinion either. A study done at Indiana State University a couple of years ago basically said the same thing, but only about athletes. They found that 80% of NCAA division I football players and 50% of NFL players were dehydrated at their preseason physicals. This wasn’t after practice this was just on a normal day. These are high level, highly trained athletes and the majority of them were dehydrated BEFORE they ever set foot on the field. They did look at a couple of other sports, and though the percentages were lower, there still were athletes beginning practice already dehydrated.
As an athletic trainer this scares me. It takes about 2% loss of body weight due to dehydration to significantly affect performance. It can affect speed, strength, endurance, reaction time, cognitive functioning, temperature regulation, and more. Chance of injury increase tremendously because coordination is down, judgment is off, and body temperatures can rise unchecked. The worst part of it is that is such an easily avoidable problem. You just need to drink more water, more often.
There are many studies out there that tell you how much you should be drinking. Unfortunately, too many of them are done by the companies that try to sell us hydration drinks and it can be hard to figure out which study to fully trust. One guideline I offer my athletes is drink 2 quarts of water in addition to everything else you drink on a given day and make sure that you drink at least 3-4 quarts of fluids a day, when not exercising. When exercising/in season, I tell them to add another 1-2 quarts a day, and maybe more on really hot days (plus drink about 1 cup/8oz for every 20-30 minutes of activity). If you go more than 2 hours during the day without needing to urinate, you may not be getting enough water, and urine, except first thing in morning, and possibly after taking vitamins or eating certain foods, should be fairly clear and mild to no odor (I also recommend that if that for every 1Lbs they lose during a workout to drink about 24oz after).
Making sure that you are properly hydrated on a daily basis not only decreases your chance of injury, but it also helps you with your day to day life and improves your health. So, drink up!