In a joint effort to update 12-year-old activity recommendations for older adults, the American Heart Association and the American College of Sports Medicine issued revised guidelines.
The full report can be downloaded as a PDF from www.acsm.org or www.americanheart.org (search 3049282). The most basic recommendations are as follows:
Do moderately intense aerobic exercise (5 or 6 on 10-point scale) 30 minutes a day, five days a week. Or, do vigorously intense aerobic exercise (7 or 8 on 10-point scale) 20 minutes a day, 3 days a week.