Q. Every few months I throw out my back. Are there any exercises I can do to strengthen my back and prevent this from happening?
A. Exercise is a great way to prevent repeat episodes of low back pain. The right exercise program will help you build strong, flexible muscles that will be less prone to injury.
Until about a century ago, most human beings were physically active most of the day. The great majority of U.S. citizens lived (and worked) on farms, and that involved a lot of walking and lifting. You may think of lifting as mainly involving the arms, but lifting something heavy involves using the back, abdominal and leg muscles as well.
Our muscles were built to support a life of frequent physical activity -- particularly a lot of walking and lifting. But that's a life few of us have today, so our muscles tend to get weak and stiff.
Weak muscles -- particularly weak back and abdominal muscles -- cause or worsen many cases of low back pain. Stretching and strengthening both your back and abdominal muscles can help prevent a recurrence of the problem.
You'll want to focus on exercises that strengthen and stretch the muscles that support your spine. Strong abdominal or flexor muscles help people maintain an upright posture. So do strong extensor muscles, which run up and down the full length of the back. They help maintain the alignment of the vertebrae, the bones of your spine. In addition, two long muscles that run from the lower vertebrae to the hips and the buttock muscles help support the back during walking, standing and sitting.
I've put illustrations and descriptions of four back-strengthening exercises on my website, AskDoctorK.com.
Stretching is equally important for a person plagued by back problems. Supple, well-stretched muscles are less prone to injury. Indeed, shorter, less-flexible muscle and connective tissues restrict joint mobility and increase the likelihood of sprains and strains.
Stretch regularly but gently. Don't bounce, as that can cause injury. Beginners should start by holding the stretch for a short time and gradually build up to roughly 30-second stretches over time.
In addition to exercises that increase the strength and flexibility of your lower back, you should engage in regular aerobic exercise. It has many benefits for general health and also helps prevent back pain. Choose activities that are low in risk and high in benefit for your back. Swimming, walking and bicycling lead the list.
Talk to your doctor about working with a physical therapist. He or she can help design a safe and effective exercise program for you. And remember the golden rule about any exercise program: Stop if it becomes painful. Exercise is meant to help, not hurt. Talk to your doctor or physical therapist about how to deal with any pain you're having.
• Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com.