There are a few reasons why this could be happening and most of them are harmless. In a few, rare instances, it could mean something more serious. If you are at all worried, please see your doctor.
Let's look at the most common causes that are what is known as 'benign' - which means that they aren't dangerous, just unpleasant.
Effort Migraine
This is commonly suffered by people who take a lot of exercise and participate in a variety of sports.
The reason for the headache is thought to be the rise in body temperature caused by intense exercise. This rise may be responsible for the blood vessels in the brain dilating, or getting bigger and pressing on nerves, giving you the headache.
People who suffer from this have often had a migraine in the past and may recognize warning signs. They may see flashing lights before the headache begins. This sort of headache usually lasts from four to six hours. The usual medicines for migraine work well for this headache, especially the preventative one. Taking a dose of a non-steroidal anti-inflammatory (NSAID) like ibuprofen, before you exercise can lower your chance of getting a headache. Trying not to get too hot can also help.
Exertion Headache
This can affect 1 in every 100 people, so you're not alone. The pattern is a sudden, intense, throbbing pain, usually at the back of the head. It will then decrease to a background ache which can go on for anything up to six hours. It is thought to be due to the increase in blood pressure and thus increased pressure in the blood vessels of the brain when you exercise. It is usually easy to control with over-the-counter painkillers.
Not tonight...I've got a headache!
Another common form of exertional headache is one that occurs regularly during or after sex. It glories in the name of 'benign coital headache'. Many people (men and women) suffer from this and are often too embarrassed to go to their doctor.
Very rarely, a person will experience a 'first time' intensely painful headache during sex. They often describe it as the worst headache of their lives. This type of sudden onset headache is an emergency - until proven otherwise. It is very unusual, but when it happens, proper emergency care is required. If you are at all worried about this type of headache, please see your doctor.
A pain in the neck
The third most common type of headache linked to exercise is called cervicogenic headache. It arises from disorders in the cervical spine. The problem can be with the muscles, joints and/or nerves.
Symptoms for this headache usually include blurred vision. The neck problems need to be resolved to prevent further headaches.
So when should I worry?
Very rarely, suffering a headache while exercising may indicate a more worrying condition.
If you have any of the following symptoms, please visit your doctor for a thorough evaluation:
A headache that starts very suddenly
A headache that gets worse over several days
Any head injury
A new type of headache that you haven't had before
A headache that has other symptoms that you're not used to
Pain on one side of the head that won't go away
Waking up in the night, or first thing in the morning with pain
A stiff neck
Numbness or tingling in any areas of the body
I repeat any of these are worth a precautionary visit to your doctor.
David has been publishing articles for nearly 6 years. You can visit his latest website at http://www.headacheheadaches.com which helps people find the best headache help.