Standing straight doesn't necessarily mean standing well. And running itself doesn't have to destroy your knees. The problem begins when the body loses active control — both when standing and upon impact.

Knee pain often doesn't appear immediately during training, but rather the next day, as the tissue gradually tires during exertion. The greatest risk then comes with changes in direction, turns, or braking, when the knee has to cope with a rapid combination of forces. It's not enough to have strong muscles—the readiness of ligaments, tendons, and other structures is also important.

The article explains why walking downhill is more demanding for the knee than walking uphill and why the disappearance of pain does not yet mean true readiness for exertion. Muscles regenerate faster than tendons and ligaments, and that is precisely why problems often return.