Here’s a two-question pop quiz about exercise intensity for you to answer:

No. 1: Only exercise performed at vigorous levels can improve your health. True or false?

No. 2: Light activities of daily living are sufficient to keep you healthy. True or false?

The answers to these questions are false and false. Both questions highlight popular misconceptions of people in this country today.

The truth is that exercise need not be strenuous in order for you to derive health benefits. On the other hand, only doing very easy activities may not keep you fit enough to prevent weight gain and chronic illness. Insufficient exercise has been linked to heart disease, stroke, high blood pressure, diabetes, osteoporosis, obesity, colon cancer, breast cancer, anxiety and depression.

No doubt about it, activity and health are definitely linked. Yet, less than half of Americans get the minimum recommended amount of physical activity. And a quarter of U.S. adults participate in no leisure-time exercise at all.

So the real questions are: What types of exercise, at what levels, are required to promote and maintain your health?

Updated guidelines

Based on research evidence that has come to light, the American College of Sports Medicine and the American Heart Association released more explicit exercise guidelines last year. The recommendations update the national exercise guidelines first published by the Centers for Disease Control in 1995. I think having this specific advice will make it a little easier for people to set their own exercise goals.

Do you want to feel great in 2008? “Engage in regular physical activity and reduce sedentary activities to promote good health, psychological well-being, and a healthy body weight,” the Centers for Disease Control says.

For healthy adults ages 18 to 65 years, here are the latest recommendations from the heart association and the sports medicine group:

Get at least 30 minutes of moderately intense aerobic exercise five days a week. This includes activities such as brisk walking, in which your heart rate increases and you break a sweat, but you’re still able to talk normally.

Alternatively, get at least 20 minutes of vigorously intense aerobic exercise three days a week. Jogging and swimming are examples of these activities, which cause your heart to pump faster and your body to burn more calories in less time. Tip: It’s OK to use a combination of moderate and vigorous activities.

The recommended amount of aerobic activity is in addition to routine activities of daily living of light intensity such as self care, cooking, casual walking or shopping.

Moderate or vigorous activities can be accumulated in increments of 10 minutes or more. This includes activities of daily living such as brisk walking, taking the stairs, yard work or vacuuming — as long as you perform them for at least moderate intensity for 10 minutes.

Do strength-training exercises twice a week. Perform eight to 10 exercises using your major muscle groups. Choose the resistance for each exercise so that substantial fatigue results after eight to 12 repetitions.

“Persons who wish to further improve their personal fitness, reduce their risk for chronic diseases and disabilities or prevent unhealthy weight gain may benefit by exceeding the minimum recommended amounts of physical activity,” the organizations report.

Their guidelines do not apply to pregnant or recently pregnant women. A final note for all adults: Consult with your doctor before significantly increasing exercise, especially if you’ve been sedentary or aren’t accustomed to physical activity.

For more information: American College of Sports Medicine, www.acsm.org.

Contact Dr. Elizabeth Smoots, a board-certified family physician and fellow of the American Academy of Family Physicians, at doctor@practicalprevention.com. Her columns are not intended as a substitute for medical advice or treatment. Before adhering to any recommendations in this column, consult your health care provider.

&Copy; 2008 Elizabeth S. Smoots