Although there are many forms of aerobic exercise, I will focus on walking--the most convenient and common type of aerobic exercise. So what is the right amount of exercise, and why is it important?
Aim for 30 minutes a day/5 days a week
Most of us know that the major benefits of aerobic exercise are increased fitness and maintenance or loss of weight. The American Heart Association (AHA) and the American College of Sports Medicine (ACSM) recommend that adults walk at a moderate pace (2 to 3 miles per hour or briskly enough to noticeably increase their heart rate) for 30 minutes at least 5 days a week. The 30 minute minimum can be achieved by performing several bouts, each lasting 10 minutes or more.
Improved fitness brings benefits but also risks
Improving fitness offers a number of health benefits that we all need, such as better circulation, lower blood pressure, and overall increased strength. Also, research shows that aerobic exercise improves mood and helps with better brain function in older adults. What could be better?
But there are some risks. According to Dr. Kerry Stewart, exercise physiologist and Professor of Medicine at Johns Hopkins School of Medicine, the results of many studies show that while individuals who consistently do more vigorous exercises accrue greater benefits, they are also at an increased risk of musculoskeletal injury. Jogging and other vigorous exercises also raises the risk of sudden death. The AHA and ACSM define vigorous-intensity exercise, exemplified by jogging, as causing rapid breathing and a substantial increase in heart rate.
Given this, couch potatoes, people over the age of 65, and those with heart conditions or high blood pressure should contact their doctor before beginning even a program of moderately brisk walking. Also, those who have been walking at a moderate rate should consider speaking to their doctor before embarking on more intensive exercises. Already vigorous exercisers should check with their doctor if contemplating moving up to running in marathons--an increasingly popular activity for people of all ages.
For weight loss
It's worth noting that First Lady Michelle Obama has championed the Let's Move campaign, advocating 60 minutes of active play each day for children in an effort to cut down on the epidemic of childhood obesity in the U.S.
It may come as a surprise that walking at a brisk pace for 35 minutes only burns about 150 calories. So, if you're interested in losing weight, it is necessary to walk for about one hour every day. If you aren't used to this amount of activity, start out in smaller increments and build up. (I am a regular walker trying to lose weight, and though not a youngster, I have found that 60 minute walks become difficult and tiring.)
Other physical activities
The AHA and ACSM also recommend that every adult should perform activities that maintain or increase muscular strength and endurance at least two days each week.
Elderly individuals should also carry out exercises to improve their balance. Poor balance contributes importantly to falls that can cause debilitating hip fractures and even death from brain injuries. Just this week my older brother called to tell me that he lost his balance and fell (but was not injured) while walking to his garage. The National Institute on Aging website details exercises that help improve strength and balance.
How to maintain an exercise program
Schedule your exercise time like a business or doctor's appointment
Walk with a family member or friend
If time constraints are a problem, consider using a pedometer to count 10,000 steps a day. In this way exercise is spread out in the course of a day so that it isn't necessary to spend 30 or more minutes exercising at a time.