Do you get enough exercise? How much exercise is enough? These questions are answered in new guidelines from The American Heart Association and the American College of Sports Medicine. Here's what they recommend.

A low level of physical activity is one of the most important factors in the high and rising rate of obesity in the United States. Becoming physically active can have a tremendous impact on your total daily energy expenditure.

For example, a sedentary person burns just a few hundred calories above his or her resting metabolic rate while going about daily activities (performing household chores or walking to the mailbox, for example), whereas someone who exercises regularly at a moderate pace doing light gardening or yard work, walking, or dancing can burn an additional 150 calories per half hour -- and build muscle mass. Exercises that build strength also raise the resting metabolic rate because muscle requires more energy for maintenance.

With this in mind, we note the new exercise guidelines released by The American Heart Association and the American College of Sports Medicine and reported in the journal Circulation (Volume 116, page 1094):

Adults ages 65 and older should engage in at least 30 minutes of moderate-intensity aerobic activity five days a week or at least 20 minutes of vigorous-intensity aerobic activity three days a week. A mix of the two intensities (for instance, brisk walking for 30 minutes and jogging for 20 minutes twice a week each) as well as short bursts of exercise for 10 minutes each will suffice. These exercise recommendations are the same as those for ages 18–65, except what is considered aerobic activity for the older group may be less intense depending on a person's fitness level.

Older people are also recommended to perform both strength-training exercises and flexibility exercises at least twice a week as well as balance exercises. The exercise guidelines -- which update recommendations issued in 1995 -- highlight that the more exercise one engages in, the better the health-protective benefits. Previously, light-intensity activities of daily living, like casual walking and grocery shopping, could be counted toward one's daily exercise total; now, however, it's believed that they aren't performed for a long enough period of time (if less than ten minutes) or at enough intensity to offer the needed benefit.