There are international guidelines for physical activity and exercise designed to improve health. Ten years ago the recommendations were for 30 minutes (or more) of moderate-to-intense physical activity five times a week. Daily exercise at this level was considered even better.
These guidelines have been update in the last year. Now the American College of Sports Medicine and the American Heart Association suggest 30 minutes (or more) of moderate-intensity aerobic (endurance) physical activity. This should be done at least five days/week.
Alternately, vigorous-intensity aerobic physical activity for at least 20 minutes on three days of the week is advised. Combining these two recommendations is even better. Aerobic activity is defined as activity or exercise that raises your heart rate up within a target range.
The age-predicted method for calculating the predicted (maximal) heart rate is 220 minus your age. For example, for your mother-in-law at 77-years old, you would subtract 220-77, which equals 143 beats/min. She should exercise at a level that keeps her heart rate below this amount.
For an aerobic workout, it’s recommended that she exercise at a level that raises her heart rate to 80 per cent of her maximum heart rate. She should do this for 20 minutes. So for a 77-year old, that would be 80 per cent of 143 or 114 beats per minute. For very active, health older adults, a slightly different formula is used: 205 – 1/2(77). Using this formula, the maximum heart rate is higher (166 beats/minute).
It’s always advisable to have a physical exam by your primary care doctor before starting a new exercise program. He or she can advise you about what’s best for an older adult with some health problems. If she gets the doctor’s go-ahead, she could join a program designed for seniors (if one is available in your community).