How Much Exercise Do I Need Again?

We're almost halfway through 2012, and I want to remind you of the current physical activity guidelines, released in 2008 by the Department of Health & Human Services.  The guide is available online, or as a downloadable PDF.  It's very readable, and provides guidelines for all ages, as well as advice for pregnant/postpartum women, adults with disabilities, and people with chronic conditions.

The basic information
Physical activity is defined generally as "bodily movement that enhances health."  This is in addition to our baseline activities - the things you do in daily life, such as standing, walking around, and lifting light objects.  Baseline activities don't contribute to the activity requirements because you generally don't do them hard enough to get your heart rate up, but you can increase them to help burn more calories (and we're also learning that simply moving around more - standing vs. sitting - can provide needed health benefits; our bodies just don't want to be sedentary).

Moderate-intensity aerobic activity  -  You're working hard enough to raise your heart rate and break a sweat.  You can talk, but not sing.  Fast walking, riding a bike on level ground, and even pushing a lawn mower are examples of moderate-intensity activities.

Vigorous-intensity aerobic activity - You're breathing hard and fast, and your heart rate has gone up quite a bit.  You won't be able to say more than a few words without pausing for a breath.  Think of jogging/running, playing basketball, and riding a bike fast or on hills.  


The other components:
Along with aerobic activity - what we usually consider cardio or endurance work - you should also work on strengthening your muscles with weight-lifting or resistance bands, or by using your own body weight, as with a pushup or pull-up.  Weight-lifting and activities such as brisk walking or jogging also produce forces that help promote bone growth and strength, another component of the guidelines.  Although science has not shown clearly whether stretching helps to prevent injury or provides a health benefit, flexibility may be an important part of your fitness routine if the activity you choose requires it.  And balance training should be incorporated for older adults who are at risk of falling - some examples are heel-toe walking, standing from a sitting position, and standing on one foot - along with moderate-intensity exercises to help improve overall muscle strength and stability. 


So what are the guidelines for adults?
For healthy people ages 18-64 and generally fit adults 65+ with no limiting conditions (find all recommendations here):

For health benefits - 2.5 hours (150 minutes) moderate-intensity aerobic activity a week and muscle-strengthening activities on 2 or more days a week (work all major muscle groups)   

OR 75 minutes a week of vigorous aerobic exercise and muscle-strengthening activities on 2 or more days a week (again working all major muscle groups)

OR  an equivalent mix of moderate and vigorous aerobic exercise (per week), with the same muscle-strengthening recommendation

Recommendations for children

Note that these are only guidelines for health benefits - increasing strength and aerobic capacity, lowering the risk for conditions such as heart disease and diabetes, helping mental health and cognitive function, and improving your daily quality of life and ability to function.  For greater benefits, and particularly for weight loss, the aerobic guideline shoots up to 5 hours of moderate-intensity activity or 2.5 hours of vigorous activity (or an equivalent mix), with muscle-strengthening.  If you have a chronic condition or other symptoms that might limit your activity, you should check with your doctor - you may need to start with less time and lower intensity.  


If this looks daunting, the good news is that you can break down your efforts into 10-minute chunks of time.  In this post I offer some strategies to find time to work out.  And there are many activities available to help you meet the recommendations.  

Another important topic in the report is reducing your risk of injury.  Do exercise that's appropriate for your fitness level, choose the right shoes and other gear, and check with a doctor before beginning a program, especially if you have chronic conditions/symptoms or are starting to exercise for the first time.  In short, most people who start slowly, progress gradually, spread their exercise throughout the week, and choose a variety of activities are much less likely to injure themselves.  

So check in with your exercise program to see how you measure up.  Need inspiration to get moving?  Read some success stories from the CDC website.  The DHHS guidelines also provide several real-life examples for people of all ages and fitness levels.  Don't be discouraged if you're limited by your current activity level or a chronic condition - even if you can't reach the 150-minute minimum, doing something is always better than nothing.  Work out as your abilities allow.  And keep in mind this line from the report:  "The best physical activity is the one that is enjoyable enough to do regularly."