USA. Arizona. Sun City West. Group exercise. Often as many as 100 people come together for an hour to do resistant exercise in the pool. Exercising in water is very beneficial as it is almost impossible to strain muscles during this sort of activity. The age range is from 60 to over 90. In this particular group there are four people over 90 - one of 94. Above all it is fun exercise and people come two or three times a week as a social get together. 2002.