You train five or six days a week, you eat like you mean it, and the annual physical comes back with more red arrows than last year. It happens to a lot of endurance athletes, and it almost always triggers the same thought: is all this training actually hurting me?

Usually the answer is no. A standard blood panel was built around a largely sedentary reference population. Training changes your muscle mass, your plasma volume, your hormone axis and the way your kidneys handle waste, so a handful of markers that read abnormal in a general population are simply what a trained body looks like at rest. The job is to tell those apart from the small set of results that genuinely needs a clinician.

This article is general education, not medical advice, and it does not diagnose anything. Reference intervals differ between laboratories. Bring the actual report to a clinician who knows your training history.