Whether you've been exercising for years or are just starting a fitness program, it's important to avoid injuries so you can keep moving toward your fitness goals. We become more vulnerable to injuries as we get older, in part because we're less agile than we used to be, and we've also lost some of our former bone and muscle mass.

"Recovery from injury can also slow with age," says Dr. Eric Berkson, an instructor in orthopedic surgery at Harvard Medical School and director of the Massachusetts General Hospital Sports Performance Center. "It can take longer to recover from a smaller injury, and the injured areas remain vulnerable during the recovery period."

Some of the most common exercise-related injuries Dr. Berkson sees include:

1. Sprains: Injuries to ligaments, the tissues that connect bones to one another

2. Muscle strains: Injuries to muscles or tendons, the tissues that connect muscles to bones

3. Tendinitis: Inflammation of a tendon, often due to overuse

4. ACL and meniscus tears of the knee: A rip in one of the ligaments that helps stabilize the knee or cartilage that cushions the knee joint

5. Rotator cuff tears: Rips in the group of muscles and their tendons that hold the arm in the shoulder socket.

To avoid getting laid up for days--or even weeks--with an injury, take these precautions when you work out:

1. Talk to your doctor

Don't start any exercise program without first checking with your primary care provider. Your doctor can determine whether you're healthy enough to exercise, and what, if any, modifications you'll need to make to your program.

"Exercise programs should be customized to the individual whenever possible to account for any limitations and ongoing medical conditions," Dr. Berkson advises.

2. Choose your workout carefully

High-impact exercise programs aren't ideal for women with conditions like arthritis or osteoporosis. Non-impact exercises, including swimming or using an elliptical exercise machine, will give you aerobic conditioning without stressing your joints.

3. Learn the proper technique

Don't start any new exercise without first learning the correct form. Work with a trainer at home or in the gym, or consult a physical therapist to help you tailor a workout to your health conditions and physical capabilities.

4. Get the right gear

Buy a pair of sturdy, comfortable sneakers that provide good arch support and have a cushioned heel to absorb shock. Wear loose, comfortable clothing that gives you room to move and breathe.

5. Start gradually