Easing up—on surfaces, strides, and miles—can help you stay healthy. "Your body absorbs about three times your weight with each step that you run," says Bert Fields, M.D., a five-decade runner who heads the sports medicine fellowship program at Cone Health in Greensboro, North Carolina. "So the most effective way to cut back on injuries may be to cut back on the pounding." Here's how.
Whether softer running surfaces are less injurious—and by how much—is debated among sports scientists: The studies are few, inconclusive, or conflicting. Complicating matters is that the answer may depend partly on your stride, foot type, weight, weekly mileage, injury history, footwear selection, and so on. Still, many coaches and elite runners believe that soft surfaces rule. For decades, elites have favored running as much as possible on dirt, grass, and sand rather than asphalt and concrete. (Should you be running barefoot? Read the debate on minimalist and barefoot running to decide.)
That doesn't mean you should go out right now and run on nothing but trails. If you've been running only on roads, you should adapt gradually with a few off-road miles each week. The uneven surfaces will vary the stresses on your feet and body, challenge you more, and let you recover faster between runs. If you have poor balance or are prone to ankle twists or Achilles injuries, avoid uneven, hazardous surfaces like rocky trails and spongy grass.