Exercise Intolerance vs. Exertion Intolerance vs. PEM
A common source of confusion are the terms "exercise intolerance" and "exertion intolerance", and how they relate to PEM. So here's a brief clarification:
- Exercise Intolerance is a medical term that refers to the inability to perform aerobic exercise. Even though the patient is trying their best to exercise aerobically, a physiological problem is depriving the exercising muscles of sufficient oxygen, resulting in rapid muscle weakness/soreness.
- Exertion Intolerance, on the other hand, is a general term that can refer to any bad reaction to any type of exertion, physical or cognitive.
- Post-Exertional Malaise (PEM), also known as Post-Exertional Symptom Exacerbation (PESE), is a type of exertion intolerance where there is an exacerbation of symptoms (and maybe some new symptoms) after minimal exertion.