How much Muscle you Build Running Ultimately Depends on how you Run When you think of sculpting your arms or building strong legs, you probably think about bodyweight moves like pushups and equipment like dumbbells and resistance bands. Do you have to swap the sidewalk for the weight room, though-or does running build muscle, too? Though most people categorize running as cardiovascular exercise, that doesn't mean you can't do more than boost your heart health and increase your VO2 max (a.k.a. Steady-state running and sprint workouts have very different effects on your body, says running and speed coach Katrina Pilkington, CPT. How much muscle you build running ultimately depends on how you run. Before we get into that, however, you should know that there's one major caveat to running's muscle-building potential. Don't expect it to build up your biceps because you'll likely only see gains on your lower body. With that in mind, here's everything you need to know about building muscle while running-plus how to switch up your routine to make pounding pavement (or, er, the tread belt) as muscle-friendly as possible. So, how does running build muscle, exactly? First, a little muscle-building 101 for you: "Muscles grow as a result of a stimulus (stress) being applied while they contract," explains Pilkington. This stimulus causes micro-damage to the muscle, and then your body mobilizes an immune response to repair it. Over time, those repairs build muscle. There are two ways running can put this necessary stress on your muscles, according to David Higgins, celebrity trainer and author of The Hollywood Body Plan. The first occurs via your horizontal movement through space.