Activities should start with a 5 to 10 minute warm-up (like walking, slow jogging or arm circles). These activities increase blood flow and warm the body in preparation for more vigorous activity. Warm-ups should be followed by several minutes of stretching. Stretching improves flexibility and reduces the risk of injury during exercise. Athletes should pay particular attention to the muscle groups most involved in the activity. The body is then ready to take on specific exercises aimed at improving muscle strength, endurance and cardiorespiratory performance. All workouts should be followed by 5 to 10 minutes of cool-down activities (like slow walking) and more stretching.

The Need to Stay Active

Exercise and physical fitness are not high priorities for many Americans. The Surgeon General reports more than 60 percent of American adults don't get the recommended levels of physical activity/day. About 25 percent of adults don't get any physical activity. Levels of activity decline with age. By 75, about 33 percent of men and 50 percent of women aren't getting any physical activity. Fitness levels aren't much better among children. Nearly 50 percent of children 12 to 21 don't get enough vigorous physical activity; 14 percent don't get any exercise.

The lack of exercise, combined with poor diet, has led to an epidemic of obesity in the U.S. The American Obesity Association reports nearly two-thirds of American adults (127 million people) are overweight or obese. More than 30 percent of children (6 to 12) are overweight.

Staying Active at all Ages

It's important to stay active throughout life. However, there are different types of precautions that may need to be taken to ensure a safe and beneficial work-out.

Active Youth

Children are often bundles of energy. However, many tend to spend their time watching television, playing video games or working on a computer. Robert Gotlin, D.O., a Sports Medicine Specialist at Beth Israel Medical Center, says the adolescent and teen years are a good time to get into the exercise habit. Children who are actively involved in a fitness or sports activity are more likely to stay active as adults.

The best way for teens to stay motivated is to find a partner or friend who enjoys the same type of activity. Work-out peers provide motivation for each other and help maintain focus and attention on the activity.

Too much exercise isn't necessarily a good thing. Some children are very sports driven. They may be playing on more than one team or competing several nights a week with no time for rest. The intense focus on sports may increase the risk of overuse injury. Repetitive minor injury to a certain area of the body (like the shoulder, elbow or knee) can eventually lead to significant damage and severe pain. Safe Kids USA says nearly half of all injuries to middle and high-school athletes are due to overuse. Gotlin recommends frequent rest periods for children (about 15 minutes rest after 30 to 45 minutes of activity). He says it's also important for children to listen to their bodies and stop the activity if they become sore, tired or feel they've been hurt.

Active Boomers

During adulthood, exercise is a good way to burn off extra calories and lose or prevent weight gain. Exercise also keeps the body in shape, builds strong bones and muscles and can reduce the risk of many different types of chronic health problems, like diabetes, high blood pressure and heart disease.

Some adults try to do too much exercise at once. Week-end athletes may spend weekdays and nights in sedentary activities and then try to push their bodies in some type of vigorous week-end activity. The sudden burst of activity increases the risk of an injury that can side-line a person for weeks.

Gotlin says middle-aged adults need to remember they don't have the body of a teenager any more. It's possible to continue vigorous activities like running or lifting weights, but boomers may need to take the exercises at a slightly slower pace. Stretching becomes a little more important to keep the body flexible and reduce the risk of injury. Middle-aged adults may experience sprains, strains, pulls or tears from a sudden change in the direction of movement. And, because of the older age, adults take longer to heal. Gotlin says an injury that would have taken three to four weeks to heal in a youngster could take 6 to 8 weeks to heal in an adult. Once the injury is healed, adults also need to ease back into activities.

Active Seniors

As people age, they tend to slow down. However, activity is still very important. During the senior years, exercise continues to help reduce the risk of chronic disease. It also maintains mobility and balance, improves stamina and flexibility. reduces the risk of falls and slows the rate of muscle loss.

Seniors may need to adapt their exercise program to accommodate physical challenges. Patients with health problems, like lung or heart disease, should consult with their physician before starting any new kind of exercise. Gotlin says the focus for older adults should be to maintain movement and flexibility. Moderate activities, like a walk in the park, riding a stationary bike, and lifting light weights, keep the body in good shape and help slow the effects of the aging process.

For general information on exercise and fitness: American Academy of Orthopaedic SurgeonsAmerican Council on ExerciseAmerican Orthopaedic Society for Sports MedicineThe President's Council on Physical Fitness and SportsShape Up America!