Balance problems in aging and Parkinson's disease can arise from the brain and muscles working too hard, not too hard. Scientists have found that with small disturbances in balance, the brain and muscles become overactive, which paradoxically weakens the body's ability to restore stability. At the same time, the muscles can contract each other, making the movement less stable and controllable. This unexpected mechanism could help scientists predict which people are at higher risk of falling. Research suggests that the problem is not muscle weakness, but muscle overactivation and lack of coordination. These findings may lead to new approaches in the treatment and prevention of falls in elderly people and patients with Parkinson's disease.