Sure, bicycling is a low-impact sport, but it’s not exactly low pain.

Nearly half of male cyclists have experienced an exercise-induced headache, often lasting into the next day, according to a new study in the journal Headache. The biggest risk factors: extreme exertion, low fluid intake and warm weather, all of which can cause dehydration. When you’re low on fluids during a hard ride, your body breaks down muscle tissue, triggering inflammation, says Dr Stephen 
Silberstein, former president of the American Headache Society. Chemicals from this process then invade your brain’s pain centres, leaving you with a head pounder.

On a tough ride, drink four cups of fluid an hour.