I used to think this would be the best excuse to get out of gym class in school, but apparently science says that you can actually be allergic to exercise. According to Popular Science, there is a condition called exercise-induced anaphylaxis. This is where an allergic reaction occurs when you exercise.

Don't start writing up those doctor's notes for the gym just yet because apparently this only effects 55 out of 100,000 people.

According to Popular Science, the reaction comes from combining certain foods with exercise and another theory is a reaction from exercise and aspirin mixing. However, there is still not a clear and precise reason why this happens. It is still getting studied and researched.