Question: How do I know whether I am going too hard, too fast, too soon with my strength training?

Answer: While many people have a desired image in mind when they begin strength training, it is important to remember that exercise works differently for everyone. There is no "ideal" body type, so finding exercises that work well for you is key to building muscle and avoiding injury.

Many of us use an inappropriate amount of weight at one point or another, especially those new to strength training. Elite athletes often use machines that measure the power and lactic acid buildup generated within their muscles to determine the appropriate amount of weight to lift. For the rest of us, the best practice is usually to start with smaller weights and work your way up. If something hurts, take a break and go back to a lower weight.

In the beginning stages of weight lifting, use predesigned circuits at the gym or ask an athletic or personal trainer for recommendations. For appropriate strength training, gym-goers need time to train and transition slowly. This is called "periodization." This slow transition from lower weight to higher weight is what creates strong muscles.

Weight lifting is an anaerobic exercise, meaning your body relies on the strength within its muscles more than oxygen while completing the exercise. It is important to include aerobic workouts to develop your muscles, such as light running, and to cross-train separate muscle groups with activities such as cycling, running, and swimming. A combination of both anaerobic and aerobic exercises will lead to better results in the long run.

Without periodization and cross-training, common weight-lifting injuries, such as shoulder injuries and rotator cuff tears or sprains, can occur easily. In addition, both new and experienced weight lifters often injure themselves when using incorrect form, rushing through exercises too quickly, or failing to give themselves enough recovery time.

If you begin to feel burned out from lifting weights, rest. If you do not recover quickly, see your doctor. Your doctor may refer you to physical therapy. Keep in mind that therapy is not the same thing as building muscle. The main focus in therapy is rehabbing muscles to bring them back to where they used to be.

Stretching is a great way to prevent injury during exercise. However, many people make the mistake of stretching only immediately before a workout. While a light warmup can help you prepare for a workout, regular stretching has been proven to improve the results of exercise and reduce injuries over time.

Listen to your body and set reasonable goals for yourself.

Michael Yang, M.D., is a sports medicine specialist at Mercy Philadelphia Hospital.