Lena Ting and her team at Emory University wanted to know how getting older or having Parkinson's disease changes the way the brain and muscles work when we try to stay upright.
In earlier tests, they asked young volunteers to lose their balance suddenly, like pulling a rug out from under them. The brainstem sent a fast signal to the muscles, and the body reacted automatically. When the disturbance was bigger, a second, slower wave of brain activity appeared.
The new study, published in eNeuro, looked at older adults, some with Parkinson's and some without. Even a tiny wobble caused much stronger brain signals and more muscle activity in these groups. Ting said, "When the brain has to work harder to keep balance, the person is less able to recover quickly."
They also saw a pattern in the muscles. When one leg muscle tried to steady the body, the opposite muscle often tightened at the same time. This extra stiffness made movements less smooth and was linked to poorer balance scores.
The researchers think their method could later help doctors spot people who are likely to fall. If the test is refined, a simple muscle check after a small balance challenge might reveal hidden brain effort.
Early detection would let clinicians start targeted balance training and exercise programs before a fall happens, giving at‑risk individuals a better chance to stay steady.