Q. My doctor wants me to start exercising to lower my risk of heart disease. I'm considering walking or running. Is one better than the other for heart health?
A. Walking and running are equally good for heart health. But there's an important caveat: If you're a walker, you have to walk more to get the same benefit.
That's what researchers found when they followed 33,000 runners and 16,000 walkers for six years. The researchers measured how much energy study participants exerted while exercising. They also kept track of how many people developed heart disease, or heart disease risk factors such as diabetes, high blood pressure or high cholesterol.
The study found that each calorie burned -- either by running or walking -- resulted in a similar reduction of heart disease risk. But overall the runners were healthier. That's because, on average, they burned more energy than walkers, probably because they could exercise in less time. Look at it this way: You have to walk for 60 minutes to use the same amount of energy as jogging for 25 minutes.
There are advantages to both walking and running. If you are over 40 and have been sedentary most of your life, I'd talk to your doctor before beginning to run. That's particularly true if you have any risk factors for heart disease and stroke -- like being a smoker, being obese, or having diabetes, high cholesterol or high blood pressure.
If you're cleared for either running or walking, choose the one you enjoy, as you're more likely to stick with an exercise you like. If you're still torn, consider these reasons to recommend walking:
• Injuries tend to be less frequent and less significant for walkers than runners.
• It's generally easier to find a place to walk than to run. A busy sidewalk or a shopping mall may be fine for walking but not so good for running.
• Walking puts less stress on the hips, knees and feet.
On the other hand, running can:
• Produce a "runner's high."
• Provide a more intense workout, which is particularly important if you have limited time to exercise.
If you decide to walk, you'll need to spend extra time to burn the extra energy. Aim for at least 30 minutes of brisk walking most days of the week. Doing just that will bring you great health benefits, in comparison to no walking or running at all. And brisk walking for 45 to 60 minutes most days of the week will bring even more benefits -- the same benefits as a person who jogs for 25 to 30 minutes most days of the week.
Whether you choose to walk or run, commit to making physical activity a routine part of your life. I've said it before and I'll say it again: There is nothing more powerful in protecting your health than regular exercise. No medicine yet invented can offer you as much protection. You can do more for yourself by exercising than anything we doctors can do for you.
• Dr. Komaroff is a physician and professor at Harvard Medical School. Send questions to AskDoctorK.com.