Did You Know!
A rare muscle disorder can make muscles work better the more you use them.
People with a genetic condition called myotonia congenita experience unusual muscle stiffness because their muscles have difficulty relaxing after contracting. For example, someone may struggle to release their grip after shaking hands or experience stiff legs when first standing up. Surprisingly, repeating the same movement often makes the stiffness temporarily improve. Doctors call this the “warm-up phenomenon.” Unlike ordinary muscle fatigue, where repeated activity can make movement harder, this condition can make certain movements easier with repetition.
