Overtraining isn't just being tired — it's when an athlete's body stops working properly and performance drops for a long time, even after resting, and it's different from regular burnout that goes away in a few weeks.

If athletes push themselves too hard for too long without enough rest, they can develop a serious condition called overtraining syndrome, where their performance gets worse and just won't improve — even after taking time off.

Paralympic athletes who train too much without enough rest or fuel might be more likely to get stress injuries in their bones, especially if they do endurance sports like racing or long-distance events.

Athletes who are really overtrained might feel more depressed or moody than those who are just temporarily worn out, and these mood changes could be an early red flag that something's wrong.

When athletes or soldiers train too much, their bodies can go into overtraining mode, which causes hidden inflammation that weakens the immune system, makes muscles shrink, messes with blood sugar, and makes them more likely to get sick.

If someone's strength keeps dropping during weight training, that might be the best sign they're overtraining—because no blood test or body measurement has proven to reliably catch it early.