A 1995 study in the prestigious "Journal of the American Medical Association" found that Tai Chi can help improve the balance of the elderly and help reduce the risk of falling. In fact, in comparison to other exercises, including weight training, stretching, endurance training, and balance training, Tai Chi was the most beneficial exercise, reducing falls and their resulting injuries 25%."

The Journal of the American Medical Association" May 3, 1995, Vol 273, No 17, pp 1341 - 1347.

Can Tai Chi Keep Shingles At Bay? It seems that T'ai Chi can certainly help... "The practice of Tai Chi, the graceful, slow-motion progression through a series of poses — some call it " moving meditation" --is known to build up strength, agility and balance. But shingles immunity? According to a study in the current edition of Psychosomatic Medicine, 15 weeks of Tai Chi seems to have helped protect a group of 18 elderly adults against the shingles virus (the same virus that causes chickenpox). One week after the study was completed, immune-cell levels increased an average of nearly 50% in those who practiced Tai Chi, while the control group showed no improvement..."

Time Magazine Sept 29th, 2003 read the rest of the article here