Ground rules: limit the risk of injury and keep your cardio efforts going full steam ahead by picking the right running surface every time - Cardio Clinic

Men's Fitness, June, 2002 by Bob Cooper

Before you start your next cardio session, consider this: According to a clinical study of 4,000 runners, co-authored by Southern California podiatrist John Pagliano, one of the five leading causes of injury is "improper" running surfaces. (The other four are training errors, inadequate shoes, faulty biomechanics and muscle dysfunction/inflexibility.)

Yet one man's unsuitable surface is another man's hallowed ground. Some guys are trail fanatics; others worship the treadmill; still others say nothing beats jogging on the beach. Nearly all surfaces have their virtues, so pick one that you enjoy (raising the odds you'll even get out there) and one that helps you reach your goal, whether it be fat loss or endurance or both.

Also consider which muscles tend to fail you. If you're prone to injuries below the knee, head for harder ground, as those ailments correlate with running on soft surfaces. Conversely, above-the-knee problems, or stress fractures in any lower-body bones, are associated with hard-surface running, so go soft.

Ultimately, the best choice may be to alternate surfaces. "Running on a variety of surfaces is a little like cross training," says Weymouth, Mass., podiatrist Robert Chasen, "because it uses your muscles in different ways, and that may reduce injury risk."

For most runners, the ideal surface is smooth and moderately (but not too) soft, and the worst is rock hard, like concrete, or irregular, like the gravelly shoulder of a crowned or banked road. That's straight from Pagliano and Chasen (both have elite running and sports-medicine credentials), who consulted with us on the following chart. Use it as a guide, but follow your own path, whether it's sandy or paved.