Getting older is a fact of life. But just because your twenties and thirties have come and gone doesn't mean your chances for a healthy physique have, too. You can keep fit and healthy well into middle age-and some body builders look better in their fifties than they did in their twenties.

But whether you're just getting into body building now or you've been doing it for some time, you need to keep in mind that age does change your body. Here are a few things over-40 body builders need to do to avoid those age-related pitfalls.

Warm up first. Younger body builders can show up at the gym and jump right in. Although this isn't advisable for any age, the younger body generally doesn't need as much preparation. When you're older, you need to put a little more time into your warm-ups. Before starting on the heavy weights, do 5-10 minutes of light cardio on a stationary bike or a treadmill. Before each heavy exercise you do, do a set of the same exercise using light weights. This will ensure your body is ready when it's time to go heavy.

Pay attention to form. As our bodies age, our joints become more and more prone to injury. Older body builders need to be especially careful about form to prevent injuries to the knees, hips, elbows, and shoulders. Compromising on form to lift more weight is a common pitfall at any age, but it's especially dangerous for those over 40. It's important to increase your weight slowly and make sure your form is flawless before doing so.

Listen to your body. Older body builders are more prone to muscle tears than younger athletes, as well. It's important to listen to your body and know the difference between normal pain that comes with improving muscle mass, and the type of pain that's warning you that you shouldn't be doing a certain movement. It's fine to limit or drop a certain exercise from your routine if it's causing you more pain than usual.

Eat right. Your metabolism slows as you age. This means your body doesn't process foods as efficiently, and it's especially important to maintain proper nutrition. In general older body builders should follow the same rules as the younger crowd, but they need to be even more strict.

Nutrition is a complicated subject-it would take a book to explain it all. But in general, stay away from saturated fats, processed foods, junk foods, and refined sugars. Eat healthy fats such as oils and omega-3 fatty acids instead. Get plenty of protein-this is especially important-and enhance your diet with protein shakes and supplements. Eat four or five solid meals a day that include vegetables or fruits and protein. Stay away from alcohol and cigarettes, and drink plenty of water.

Give yourself time to recover. As we age, we take longer and longer to recover from injuries. If you're on a roll with your workout, it can be tough to accept a slowdown because of an injury. When you're younger, you might be able to get away with going back to the gym long before your doctor gives permission. But when you're older, you're much more likely to re-injure yourself if your body isn't ready to take the strain. If you're injured, listen to your doctor and don't go back to the gym until your body is ready.

Coming back after a long break? Start slowly. If you're coming back to body building after a break of years or even decades, don't expect to be able to do everything you could when you were young-especially not right away. And if you're coming back after an injury, it's especially important to start slowly. Your body needs time to adjust. When you're older your joints have less lubrication and your muscles have reduced elasticity, making both prone to injury. It doesn't mean you'll never be able to reach the level of fitness you were once at, but it does mean you'll have to take extra time to get there.

Work out smarter, not longer. Most body building experts will tell you that as you age, it's important to get the most from each rep that you do. The longer you spend in the gym, the more opportunities you have to tear a muscle or injure a joint. You don't need to go to the gym every day-three or four times a week is enough. Decrease the amount of reps that you do while increasing their effectiveness; make sure your form is correct. Do one exercise for each muscle group, not two or three. You should be able to get results from an hour or so at the gym-there's no need to be there all day.

Raise testosterone naturally. Testosterone helps you burn fat and add muscle. When you age, your body's natural production of testosterone tends to fall off. There are hormone supplements out there that some body builders swear by, but the side effects can be negative. If you don't want to risk it, you can boost testosterone production through exercise and diet.

Studies have shown that heavy, compound exercises that put large muscle groups to work can give your body a burst of testosterone. Squats, barbell rows, and bench presses fall into this category. If you have a high body fat index, your body will have lower levels of testosterone and higher levels of estrogen-so losing the weight is essential. Some foods, such as monounsaturated fats like nuts, olive and canola oil, and peanut butter, can also help you raise your testosterone levels.

Life doesn't end after 40. Many successful body builders didn't start lifting weights until they were 40 or older, and many others have continued a successful weight lifting career into their 80's. You're never too old to live a healthy lifestyle, and it's never too late to start.

About the author

Jean Lam is the webmaster of Body Building Resource which provides articles on weight training, nutrition and fitness, body building book and DVDs.