It's not that uncommon to get a headache after a workout, especially if the exercise is vigorous. Exercise headaches are more common with exercise that drastically raises the heart rate, such as running, swimming and strength training. There are multiple reasons why exercise headaches happen, and the best way to resolve the problem is to figure out why they happen.
The Definition of an Exercise Headache
An exercise headache occurs when you do strenuous physical activity requiring a lot of high energy that provokes a headache during exercise or after exercise.
Primary and Secondary Reasons for Exercise Headaches
The Mayo Clinic has two different categories for exercise headaches. The primary reasons for exercise headaches are harmless and can be resolved with proper knowledge and training. Secondary reasons for exercise headaches are always connected to bigger health issues that may or may not be known. If the exercise headaches are severe, turn into migraines or last for several hours or days after exercise, it is wise to seek the help of a health care professional (see References).
If you exercise after long periods of going without food you may get an exercise headache. This can happen if you exercise first thing in the morning and you haven't eaten since 6 p.m. the night before. It can also happen if you exercise late in the afternoon, before dinner, and haven't eaten for five or six hours. Everyone's body is different and you have to learn how your body works and what it needs.
Dehydration can be the cause of exercise headaches. If you do not stay properly hydrated before, during and after exercise, your body cannot properly use its energy. Try drinking an 227gr glass of water before exercise, drink another 236ml glass of water during exercise (or more if needed), and then another 227gr after exercise.
When exercise moves from the moderate phase to the strenuous phase, the blood vessels in your head begin to dilate to help keep up with the work your heart is doing. This dilation of the blood vessels causes a headache.
Exercise can cause an injury that you might not always recognise right away. A sudden headache can be a sign that you have pulled or pinched something. If you do not properly warm up before exercise you can pull muscles and pinch nerves that can cause headaches. Always warm up properly before any kind of exercise, but definitely before vigorous exercise.