The safety and benefits of swimming for middle-aged and elderly swimming beginners were investigated using two groups participating in the primary level class of a swimming school. Ex. 1 was performed using two subgroups: "Under", 1 man and 2 women (38-64 yr), who could not swim and "Over", 2 men and 2 women (42-80 yr) who could swim, but not more than 50 m. The intensity of swimming for the Under group which was computed by heart rate achieved during the swimming class was mostly 40-80% of the predicted VO₂max. On the other hand, for the Over group, 48% of class hour showed a rate of less than 40% of the predicted VO₂max. Nobody but three in Ex. 1 showed a systolic blood pressure of more than 200 mmHg. Ex. 2 was performed using swimming beginners, 4 men and 7 women (45-80 yr), symptom-limited all-out test on a treadmill in the middle of, and after swimming training. Body weight, CPK, TG and Tcho showed no change, but total skinfolds thickness was decreased. The rate of decrease depended on the original thickness and not on the exercise hour. According to the rate of increase VO₂max, the subjects were divided into two subgroups: "Unchanged" and "Increased". The differences between the two subgroups were in swimming hours/day, walking hours/day computed as 7000 steps being equivalent to 1 hour, and especially the total of both, which was over 80 min for the Increased group and less than 70 min for the unchanged group. Our conclusions are as follows: 1) swimming is safe for middle-aged and elderly beginners, 2) a decrease in skinfolds thickness can be obtained through exercise at over 40% VO₂max over a period of 60 or 90 min, once a week, and the degree of decrease depends on the original thickness, 3) an exercise prescription should be decided according to the subject's daily activity. It is at least possible to recommend the following exercise schedule for increasing VO₂max for the middle-aged and elderly: a) 8000 steps per day plus exercise at over 40% VO₂max over a period of 60 or 90 min, once a week, or b) 6000 steps per day plus the same exercise, but done three times a week.

DESCENTE SPORTS SCIENCE Vol.9/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE