It's surprisingly common - you're exercising, everything's fine, and then POW - a headache strikes! Or, sometimes, a headache hits while you're exercising. Is it just a minor annoyance? Or could it be a signal that something serious is going on? Should you go to the doctor, or just shrug it off?

If you already suffer from headaches or migraine, it may just be that your exercise is starting the headache chain-reaction. In that case, it's important to look at the overall picture and make sure you're getting the treatment you need for headaches. Your doctor may recommend a pain killer to take just before you exercise, to stop the pain before it starts. In the case of migraine, this is called an "effort migraine", and it's very common. A throbbing headache in the back of your head may be an "exertion headache", which again usually requires some pain killers and is not serious.

But after exercise headache can be a warning that something serious is going on. As a general rule of thumb, if you get a new headache after you exercise, you should see a doctor right away. Any sudden change when it comes to headache could be a sign of something serious, so don't wait.

Some of the more serious headaches have to do with the blood vessels in the head. A headache after exercise could indicate an abnormality in the blood vessels themselves, or could warn you of a brain hemorrhage (or haemorrhage) (blood flow when blood vessels break).

If you're exercising in the heat and begin to have sore muscles, difficulty breathing, and dizziness along with headache, you could be experiencing early signs of heat exhaustion or heat stroke. You'll soon be past helping yourself, but friends will need to make sure your body is cooled off quickly.

Of course, everyone is afraid of brain tumours. Tumours (tumors) are very rare, so don't panic at the first sign of headache. Unlike typical headaches, these generally get worse over the course of several weeks, and are usually worse in the morning. They get worse when you exercise, and almost always include other symptoms, such as blurred vision, unsteadiness or weakness. Again, if you get a new headache, see your doctor right away. You want to catch these things as early as possible.

Here are some other things that may tip you off that your exercise headache is very serious:

- You have injured your head in the past

- You experience paralysis or a tingling sensation

- Your neck is stiff

- You're waking up at night with pain

- The headache isn't going away

- You're experiencing other symptoms elsewhere

- Any other change in symptoms

Remember, even if you have other symptoms, it may not be an immediate problem. But it's worth it to talk to your doctor and remove all doubt. Even if it's not a sign of another disease, dealing with the pain will help you benefit more from exercise and your relaxing time too. Your health is worth it!

James Cottrill is a health writer at http://www.relieve-migraine-headache.com . He lives with his wife and children in the shadow of the Canadian Rocky Mountains. You can read more about exercise headache at http://www.relieve-migraine-headache.com/after-exercise-headache.html