ACSM'S Health & Fitness Journal:
Departments: You Asked For It: Question Authority
Nieman, David C. Dr.P.H., FACSM
David C. Nieman, Dr.P.H., FACSM, is professor and director of the Human Performance Laboratory, Appalachian State University in Boone, North Carolina; an active researcher; and author of several textbooks on health and fitness. Send your questions to email@example.com.
Q: I HAD A QUESTION ABOUT AEROBIC EXERCISE PROGRAMS. IS IT MORE ADVANTAGEOUS TO EXERCISE ONCE A DAY OR BREAK THIS UP INTO TWO OR THREE SHORTER SEGMENTS?
A: The best research now shows that both types of exercise programs have similar beneficial effects on your fitness and health.
The American College of Sports Medicine (ACSM) and the American Heart Association (AHA) in their recent summary of the medical literature on physical activity and health concluded that "moderate-intensity physical activity in shorter bouts (usually lasting 10 minutes) that is accumulated toward the 30 minute minimum can be as effective as single, longer bouts in affecting chronic disease risk factors" (1). The health effects of three 10-minute exercise bouts per day compared with 30-minute bouts are similar, emphasizes the ACSM/AHA, when measuring improvements in fitness, blood pressure, blood lipids, and weight control.
According to ACSM/AHA, all healthy adults need moderate-intensity aerobic (endurance) physical activity for a minimum of 30 minutes on 5 days each week or vigorous-intensity aerobic physical activity for a minimum of 20 minutes on 3 days each week to promote and maintain health (1). These guidelines also apply to older adults (2). Moderate-intensity aerobic activity, which is generally equivalent to a brisk walk, can be accumulated toward the 30-minute minimum by performing bouts each lasting 10 or more minutes. Vigorous-intensity activity such as jogging causes rapid breathing and a substantial increase in heart rate.
ACSM/AHA recommends that when splitting up the day's physical activity routine, each bout should be at least 10 minutes (1). Activity bouts below this duration threshold may not be of sufficient magnitude to improve fitness and health. Furthermore, this recommended amount of aerobic activity is in addition to routine activities of daily living of light intensity (e.g., self-care, cooking, casual walking, or shopping) or lasting less than 10 minutes in duration (e.g., walking around home or office or walking from the parking lot). However, moderate- or vigorous-intensity activities performed as a part of daily life (e.g., brisk walking or cycling to work, gardening with a shovel, or splitting wood) and performed in bouts of 10 minutes or more can be counted toward the recommendation (1).
The old recommendation that adults "should accumulate 30 minutes or more of moderate-intensity physical activity on most, preferably all, days of the week" (3) was misinterpreted by some who believed that the light activities of their daily lives were sufficient to promote health (1). The new physical activity guidelines are more explicit in regard to the frequency of exercise and importance of vigorous exercise. Also, they now clearly state that aerobic activity programs are in addition to the routine activities of daily living. The updated recommendations emphasize that moderate- and vigorous-intensity physical activities can be combined and have similar health benefits (1). For example, a person can walk or cycle briskly for 30 minutes twice during the week and then jog for 20 minutes on two other days (1).
Persons who wish to further improve their personal fitness, reduce their risk for chronic diseases and disabilities, or prevent unhealthy weight gain benefit by exceeding the 30-minute moderate-intensity physical activity minimum (1,2). Also, if skeletal health is a concern, emphasis should be placed on extra weight bearing and higher-impact activity such as stair climbing, jogging, and vigorous sports, as tolerated (1). The U.S. Departments of Health and Human Services and Agriculture recommend three levels of physical activity depending on individual goals (4): the protection against selected chronic diseases (≥30 minutes of moderate-intensity exercise on most days), prevention of unhealthy weight gain (approximately 60 minutes of moderate- to vigorous-intensity activity on most days), and to sustain weight loss in adults who have lost substantial body weight (participate in at least 60 to 90 minutes of moderate-intensity activity daily).
In summary, aim for 30 to 60 minutes of moderate-intensity physical activity 5 days each week or at least 20 minutes of vigorous-intensity activity 3 days a week. As you accumulate these activity minutes, make each activity bout last at least 10 minutes. For example, if you enjoy brisk walking, then aim for three to six 10-minute bouts in a given day, two to four 15-minute bouts, or one to two 30-minute bouts. Although this may seem a daunting task within an already busy schedule, the fitness and health benefits are of inestimable value. Our bodies have an inherent design for movement, similar to the necessities of eating and sleeping. Every day you achieve the 30- to 60-minute moderate-intensity physical activity goal, you will be rewarded with improved health and fitness that, over time, translates to a longer high-quality life.
1. Haskell, W.L., I.M. Lee, R.R. Pate, et al. Physical activity and public health: updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Medicine & Science in Sports & Exercise®
2. Nelson, M.E., W.J. Rejeski, S.N. Blair, et al. Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Medicine & Science in Sports & Exercise®
3. Pate, R.R., M. Pratt, S.N. Blair, et al. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. Journal of the American Medical Association
4. U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary Guidelines for Americans
. 6th ed. Washington: U.S. Government Printing Office, 2005.