Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School, Brigham and Women's Hospital. Two recent reports from the UK (England and Scotland) shed light on several key questions about physical activity and health, including how much, how often, and what type is best.
As you know, current physical activity guidelines recommend moderate-intensity exercise for about 30 minutes most days of the week (a total of 150 minutes/week) or vigorous exercise for half that amount of time (75 minutes), spread out over three or more sessions per week. In a report published in JAMA Internal Medicine, researchers asked a large cohort of more than 63,000 men and women over age 40 about their moderate to vigorous physical activity. Participants were classified into one of four groups: those who did no moderate or vigorous physical activity, those who met the guidelines (150 or 75 minutes/week) and exercised at least three times per week, those who met the guidelines but compressed the activity into one to two sessions per week (commonly referred to as "weekend warriors"), and those who reported some moderate to vigorous physical activity but less than the guidelines.
The results were surprising. All of the active groups, compared with the group not having any moderate to vigorous activity, had substantial reductions in cardiovascular and all-cause mortality. Weekend warriors and those getting less than the recommended amount, compared with those getting no moderate to vigorous exercise, had close to a 30% reduction in all-cause mortality. Those meeting the guidelines and having at least three sessions per week had a 35% reduction in all-cause mortality. So there was not too much difference. All three active groups had about a 40% reduction in cardiovascular mortality compared with those who did not report any moderate to vigorous activity.
In a second report from the UK cohort, published in the British Journal of Sports Medicine, researchers asked participants about specific types of sports and moderate to vigorous activities that they engaged in. What they found was very interesting. A really wide range of sports and leisure-time activities were associated with substantial reductions in all-cause and cardiovascular mortality, including swimming, racket sports, and aerobics. Similar reductions in cardiovascular mortality were found with these types of activities.
It is a very good clinical public health message that some moderate to vigorous physical activity is substantially better than none, and that more is at least slightly better than some. We should encourage patients who are unable to meet the target, or who have to compress activity into one or two sessions per week or the weekend, to stick with it and be as active as they are able. We can expect that any activity will be better than none.
We need more research on physical activity and health, including randomized clinical trials of different types of activity, to further refine the activity guidelines. Thank you so much for your attention. This is JoAnn Manson.
Physical Activity Guidelines for Americans Recommendations
6 to 17 years
Children and adolescents should do 60 minutes (1 hour) or more of physical activity daily.
- Aerobic: Most of the 60 or more minutes a day should be either moderate-a- or vigorous-intensityb aerobic physical activity, and should include vigorous-intensity physical activity at least 3 days a week.
- Muscle-strengthening:c As part of their 60 or more minutes of daily physical activity, children and adolescents should include muscle-strengthening physical activity on at least 3 days of the week.
- Bone-strengthening:d As part of their 60 or more minutes of daily physical activity, children and adolescents should include bone-strengthening physical activity on at least 3 days of the week.
- It is important to encourage young people to participate in physical activities that are appropriate for their age, that are enjoyable, and that offer variety.
18 to 64 years
- All adults should avoid inactivity. Some physical activity is better than none, and adults who participate in any amount of physical activity gain some health benefits.
- For substantial health benefits, adults should do at least 150 minutes (2 hours and 30 minutes) a week of moderate-intensity, or 75 minutes (1 hour and 15 minutes) a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic activity. Aerobic activity should be performed in episodes of at least 10 minutes, and preferably, it should be spread throughout the week.
- For additional and more extensive health benefits, adults should increase their aerobic physical activity to 300 minutes (5 hours) a week of moderate-intensity, or 150 minutes a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity activity. Additional health benefits are gained by engaging in physical activity beyond this amount.
- Adults should also include muscle-strengthening activities that involve all major muscle groups on 2 or more days a week.
65 years and older
- Older adults should follow the adult guidelines. When older adults cannot meet the adult guidelines, they should be as physically active as their abilities and conditions will allow.
- Older adults should do exercises that maintain or improve balance if they are at risk of falling.
- Older adults should determine their level of effort for physical activity relative to their level of fitness.
- Older adults with chronic conditions should understand whether and how their conditions affect their ability to do regular physical activity safely.
a Moderate-intensity physical activity: Aerobic activity that increases a person’s heart rate and breathing to some extent. On a scale relative to a person’s capacity, moderate-intensity activity is usually a 5 or 6 on a 0 to 10 scale. Brisk walking, dancing, swimming, or bicycling on a level terrain are examples.
b Vigorous-intensity physical activity: Aerobic activity that greatly increases a person’s heart rate and breathing. On a scale relative to a person’s capacity, vigorous-intensity activity is usually a 7 or 8 on a 0 to 10 scale. Jogging, singles tennis, swimming continuous laps, or bicycling uphill are examples.
c Muscle-strengthening activity: Physical activity, including exercise that increases skeletal muscle strength, power, endurance, and mass. It includes strength training, resistance training, and muscular strength and endurance exercises.
d Bone-strengthening activity: Physical activity that produces an impact or tension force on bones, which promotes bone growth and strength. Running, jumping rope, and lifting weights are examples.
Source: Adapted from U.S. Department of Health and Human Services. 2008 Physical Activity Guidelines for Americans. Washington (DC): U.S. Department of Health and Human Services; 2008. Available at: http://www.health.gov/paguidelines. Accessed August 6, 2015.