New guidelines on physical activity were released late in 2008 by the U.S. Department of Health and Human Services. What does this mean for you? It means that there is now a clear set of guidelines, based on the latest, most sound science to help guide your fitness plan. The guidelines take the guesswork out of how much exercise you should do and what type of exercise is best – making it easier for you to begin realizing a healthier lifestyle.

Throughout the years, many organizations have issued exercise recommendations. These guidelines, however, were not always consistent and did not always give clear strategies for implementation. "Guidelines from other groups haven't been uniform and often conflicted with each other," says Rod K. Dishman, Ph.D., professor of kinesiology and adjunct professor of psychology at the University of Georgia in Athens, Ga., and a member of the committee that released the new guidelines. "These new guidelines, however, offer a single, uniform message based on cumulative scientific evidence."

The guidelines, which take into account the needs of people of all ages and physical conditions, tell you what types of activities are best and how much is recommended. "We're hoping this will reduce the confusion about physical activity and help people move from thinking about exercise to doing it," Dishman says.

Research clearly shows that regular physical activity provides many benefits. Reducing risk of diseases like cancer and heart disease are some of the many long-term benefits. Other benefits, like increased strength, increased fitness and improvements in mood and blood pressure can appear within a few weeks or months of participation in physical activity. Below is a summary of the government's exercise recommendations for adults and children. Take them to heart, and you'll begin to reap the rewards that regular exercise can bring.

Exercise guidelines for adults

Are you a beginning exerciser or have you been exercising regularly for years? No matter how active you are now, the guidelines can help you attain optimal health. Here's what the guidelines recommend:

2.5 hours of moderate physical activity, like brisk walking, water aerobics, ballroom dancing or general gardening each week

OR

1 hour and 15 minutes of vigorous aerobic activity each week, like jogging, playing tennis, swimming laps or jumping rope

OR

An equivalent combination of moderate and vigorous activity. These activities should be performed in episodes of at least 10 minutes, and spread throughout the week.

AND

Muscle-strengthening activities like strength training, carrying heavy loads or heavy gardening at least two days a week.

That might sound like a lot, especially if you're new to exercise. But remember that these guidelines are long-term goals, and if you're new to exercise, you can start with a smaller amount and progress gradually. One of the key recommendations in the guidelines is that adults should avoid being inactive. Some activity is better than none and starting small can help you move from inactivity to a fitter, more active lifestyle.

One way to start slowly is by adding 10-minute chunks of activity like walking your dog, gardening or playing tag with your kids several times a week. Just make sure you're choosing activities you enjoy so you're more likely to stick with them. After several weeks, gradually increase how much you're exercising. For example, if walking is your primary form of exercise, start with 10-minute walks several times a week. Then increase to 15-minutes, and after a few more weeks, add another day of walking. Later, you can pick up the pace and walk longer and a little faster.

If you're already doing 2.5 hours of physical activity every week, give yourself a pat on the back and then get ready to step it up. By adding more time to your exercise program, you'll get even more benefits. In fact, for maximal benefits, the guidelines recommend moving from 2.5 hours of moderate-level activity a week to five hours or more a week.

You should also replace some of those moderate-level activities with more vigorous aerobic activities that will increase your heart rate and make you even fitter. For instance, if you play doubles tennis, you might give singles tennis a try one or two days a week. Or if you're a walker, just by picking up the pace and doing fast walking for 15 minutes during your 30-minute walk, you can gain more benefits.

But what about muscle-strengthening activities? As you'll see, the guidelines recommend doing them two times a week for all of the major muscle groups, including the legs, hips, chest, back, abdomen, shoulders and arms. One of the most common ways to do this is through strength training using your body weight or tools like dumbbells or resistance tubing to challenge your muscles. Ideally, you should do eight to 12 repetitions of each exercise. If you've never done strength training, you need to learn proper form so consult with a certified personal trainer, watch a DVD or read a book before you begin. Climbing stairs, carrying heavy loads and doing heavy gardening also count as muscle strengthening activities.

Want more help figuring out how to get the right amount of activity in your day? Click here to see suggestions for fitting exercise into your day.

Exercise guidelines for children and adolescents

Exercise isn't just for adults. Kids need to exercise, too. Children who are regularly active are more likely to remain healthy as adults. Here's what the guidelines advise for kids aged six to 17:

• At least one hour of physical activity every day. This can include either moderate (i.e. hiking, biking or brisk walking) or vigorous (i.e. jumping rope, running and playing soccer) intensity activity — but vigorous activity should be done at least 3 days a week, and part of the 60 minutes should include:
• Muscle-strengthening activities like rope climbing, sit-ups and tug-of war three days a week.
• Bone-building activities like jumping rope, running and skipping three days a week.

There are also guidelines for older adults, pregnant women, and adults with disabilities.
See Chapter 7 in the guidelines for more information.

How to prevent injuries

The more physically fit you are, the less chance you'll have of injuring yourself. To reduce your change of becoming injured while exercising, follow these tips:

• Always start slowly and build up gradually, especially if you haven't done any physical activity in a while.
• Learn about the types and amounts of activity that are best for you.
• Choose activities appropriate for your fitness level.
• Gradually increase the time you spend exercising before switching to activities that take more effort.
• Use the right safety gear and equipment for all activities.
• Choose a safe place to do your activity.
• See a health care provider if you have any health problems.