How many times have you heard the case of someone who developed a chronic condition, or even died, and still they were super fit and healthy? The answer to that is inflammation. Overdoing it. Could be oxidative stress or some sort of metabolic dysfunction. It specially happens to the “cardio” people (marathon runners, cyclists), but also the “HIIT” ones (bootcampers, crossfitters… including myself at some point – you just feel it), and the Powerlifters and Olympic lifters, because of the excessive metabolic demand.