Rules of Thumb

If you're new to physical activity, haven't been active in a long time, or are trying a sport or activity for the first time, it's important to start out slowly and build up your activity gradually so you don't get hurt.

For instance, if you decide to start walking, begin by doing 10 minutes at a time. After a couple of weeks, you can increase your time to 20 minutes and then 30 minutes, 45 minutes, and eventually an hour. To realize health benefits, aim for at least 30 minutes of moderate physical activity, such as brisk walking, at least five days a week.

If you're starting a strength-training program, talk to a fitness instructor about how much weight to begin lifting, what exercises to do, and how often. If you're working with weight machines, learn how to use them correctly. Don't work the same muscles two days in a row. Instead, vary your activities daily to work different muscles and keep your routines interesting. Don't forget to warm up with some simple stretches before your routine, or by walking or marching in place.

For aerobic exercise, a good rule of thumb to see if you're working at the right pace is the "talk test." If you can't talk during the activity, you're working too hard. If you can belt out a show tune, you can pick up the pace.

Another guideline is the 10 percent rule. Don't increase your program (walking distance or amount of weight lifted) by more than 10 percent a week. So if you start out walking a mile, don't go more than an extra one-tenth of a mile, or about two blocks, the following week.

"The bottom line is to use common sense," says Michael Carius, M.D., an emergency doctor at Norwalk Hospital in Norwalk, Connecticut. But a lot of people don't use common sense when they first start exercising. "If you want to run or bike, start out going short distances. Start with the lowest setting on the treadmill and gradually build up."

When to Exercise Caution

Most healthy adults can start moderate physical activity as soon as they're ready. If you have any of the following conditions, you'll most likely benefit from exercise, but you should talk to your doctor before you begin:
heart problems

• chest pains
  
• high blood pressure
  
• dizziness or balance problems
  
• asthma
  
• bone or joint problems
  
• diabetes
  
• any new, undiagnosed symptom, such as weakness or headaches

Here are some other tips to keep you safe when you're working out:

Check your environment. Where you're exercising in needs to be safe, advises Carius. That means it should be well-lit and free of things you can trip over, such as wires or loose carpet. Any equipment you're using should be in good working order.

Warm up and cool down. Always warm up your body before you begin a workout. If you march in place, move your arms. Then do some stretching for your arms, legs, and back. Repeat the stretches after your workout.

Drink up. If you're planning to exercise for an hour or more, drink more water than you think you need before, during, and after exercise to avoid getting dehydrated. Drinking 10 to 16 ounces of water two hours before your activity will give your body time to get rid of extra liquid and offset fluid lost from sweating. During your first hour of exercise, drink five to 12 ounces of water every 15 to 20 minutes. If you exercise more than an hour, make it a sports drink to replace lost carbohydrates and electrolytes. After exercising, drink at least two cups of water for every pound of sweat you lose (weigh yourself before and after your activity).

Wear proper safety gear at all times. If you're biking or skating, wear a helmet that fits snugly. Wearing a bike helmet can cut your risk of serious head injury by up to 85 percent, according to the U.S. Consumer Product Safety Commission. Wrist, elbow, and knee pads add protection during skating. Some sports, such as martial arts, require mouth guards, shin and arm guards, or other padding. Find out what you need and wear it.

Don't scrimp on gear and clothes. Make sure your gear and equipment are good quality, even though it might cost more. If you're a runner or hiker, invest in a good, sturdy pair of running or hiking shoes. If you're into cycling, buy a decent bike. Quality gear pays off. It will lower your risk of injury and last longer.

Don't mess with Mother Nature. Take the weather seriously if you're active outdoors. Be especially careful when it's very hot. Drink plenty of water, wear light clothing, and try to stay in the shade. Pay attention to air quality and try to work out when and where there are fewer cars on the road. Dress warmly and in layers if you exercise in cold weather. Avoid ice and be careful of snow, especially if it blocks your view of traffic.

Listen to your body. "People know their bodies better than anyone else does," says Carius. "If you feel something out of proportion to the level of exercise you're doing, step back and evaluate yourself." Carius says to note any changes in normal feeling, including:

• lightheadedness
  
• shortness of breath
  
• sudden, severe headache
  
• excess sweating that's out of proportion to your level of exertion
  
• chest, stomach or any other pain

See a doctor if your symptoms don't go away.

Regular physical activity has many health benefits. You'll build stronger bones and muscles, control your weight, and are able to fight colds and stress better. Work out safely and reap the rewards!

Sources: U.S. Consumer Product Safety Commission; American Academy of Orthopedic Surgeons; American College of Emergency Physicians; "Food As Fuel: How to Nourish and Strengthen Your Physically Active Body"
AARP Resources