Poor balance, a persistent problem for millions of Americans, triggers many falls. In young, healthy adults, balance is largely an automatic reflex. However, gradual changes linked to growing older-such as weak or inflexible muscles, slower reflexes, and worsening eyesight-affect the sense of balance. Certain health problems-such as inner ear disorders, neuropathy, and heart rhythm disturbances-may upset balance, too. So can alcohol and many medications....