INDIANAPOLIS – Healthy adults ages 18 to 65 need moderate-intensity aerobic physical activity for at least 30 minutes five days each week or vigorous-intensity aerobic physical activity for at least 20 minutes three days each week, according to updated physical activity guidelines released earlier this month by the American College of Sports Medicine (ACSM) and the American Heart Association (AHA).

In addition, adults benefit from performing activities at least two days each week that maintain or increase muscular strength and endurance. The two groups recommend that eight to 10 exercises using the major muscle groups be performed on two non-consecutive days. To maximize strength development, a resistance (weight) should be used for eight to 12 repetitions of each exercise resulting in willful fatigue.

The preventive recommendation specifies how adults, by engaging in regular physical activity, can promote and maintain health and reduce risk of chronic disease and premature death.

The groups also released a companion recommendation for adults ages 65 and older and adults between the ages of 50 and 64 with chronic conditions or physical functional limitations.

The recommendations are an update and clarification of the 1995 recommendation from the Centers for Disease Control and Prevention and ACSM on the types and amounts of physical activity needed by healthy adults to improve and maintain health.

The core recommendation remains fundamentally unchanged despite the fact that more than 10 years have passed since it was issued. New science has been evaluated to understand the biological mechanisms by which physical activity provides health benefits and the physical activity profile (type, intensity, amount) that is associated with enhanced health and quality of life. The new guidelines reflect a review of that evidence and consider key issues not fully clarified in the original recommendation.

One of the recommendations is that more is better. The guidelines emphasize that physical activity above the recommended minimum amount provides even greater health benefits. The guidelines also clarify what short bouts of exercise are and that doing them is OK. The original recommendation introduced the concept of accumulating short bouts of physical activity toward the 30-minute goal, but there was confusion about how short these episodes could be. For consistency, the minimum length of these short bouts is clarified as being 10 minutes. In addition, the new guidelines now recommend muscle strengthening.

The papers have been published jointly in Medicine & Science in Sports and Exercise®, ACSM’s official journal, and Circulation, a journal of the American Heart Association. For more information or additional details on the physical activity guidelines, please visit www.americanheart.org/fitness or www.acsm.org.