Most of the time, these headaches are caused by dehydration. Make sure that you are drinking enough water – even before you head out the door. Not only the day before, but you need to start hydrating a few days before your scheduled long run. You know that you are properly hydrated if your urine is clear or pale in color. The day of your run, you need to drink at least 16 ounces of water about an hour before you head out the door. Then drink about 4 ounces right before you leave.
During your run, if you are running longer than an hour, you should drink about 6-8 ounces of water every 30 minutes. For even longer runs, you may want to make one of your stops for a sports drink so that you can replace electrolytes lost. When you finish your run – make sure that you drink at least 20 ounces of water for replenishment.
Make sure that you are eating something about an hour before your long run. Many people, myself included, will get headaches if they don’t eat. And, if you run in the mornings, you’ve gone many hours without eating. A banana and yogurt is a great light snack before your run. Personally, I’ll have either ½ or a whole Power Bar before I head out in the morning. It gives me the energy I need to complete the run without weighing me down.
The sun can be another cause of runner’s headaches. If the sun is bright and you are constantly squinting – the result can be a headache. Wearing sunglasses and a cap will help with this. Also, try to not run during the heat of the day.
Usually running-induced headaches are harmless. Taking an ibuprofen or pain reliever should also help. As with anything, if these headaches last more than a day or you start getting more serious symptoms, please see your doctor. It could be something more serious than simply a running headache.