Sure, the excuse “I can’t run, it’ll hurt my knees” has gotten legions of couch potatoes off the hook—but its usefulness may have finally run out.

Healthy men and women ages 18 to 35 who ran for 30 minutes didn’t experience soreness and/or swelling in their joints—in fact, running actually reduced inflammation, according to a Brigham Young University study.

In other words, running may not only help you feel better in and out of the gym, but also make you less likely to get a joint disease like osteoarthritis.

That alone warrants a few victory laps...but where should you do them?

Is it better to run on a trail or treadmill?

Opt for running outside rather than on a treadmill whenever possible, says Harvard Medical School’s Irene Sprague Davis, Ph.D.

“When you run outdoors, you’re constantly varying your speed, and the terrain and surfaces are always changing,” says Sprague Davis, an expert in the differences between treadmill and overground running. “These changeups provide greater variability to your musculoskeletal system”—much better than the repetitive stress incurred from a treadmill workout.

Oxygen consumption and muscle recruitment are also higher when you run outdoors compared with pounding a treadmill belt.

Throw in that wind resistance—which can increase a runner’s workload by 2-10%, depending on his speed—and running al fresco wins every time.

How to stretch to reduce knee pain while running

Because each foot strikes the ground about 1,000 times per mile when you run, Davis suggests adding some stretches and yoga to counteract stiffness and prevent injury while you’re getting back your outdoor-run mojo.

Pre-run, dynamic stretches like leg swings, high knees, butt kicks, and walking lunges loosen up muscles. Post-run, yoga-based stretches like runner’s lunge, warrior one, supine split, and half pigeon help range of motion; stave off swelling and soreness; and keep anti-inflammatory powers strong.

There are also some simple running tricks to avoid knee pain: Lean from your ankles not your hips (like a ski stance) and take shorter strides (count how many times your feet hit the ground in one minute, and shoot for 80 strikes per minute per foot).

The BYU study also found that, compared with running, sitting is substantially worse for the knees. So, couch potatoes, the race starts now. Use this absolute beginner's guide to running and take the first step.