If you're starting or increasing a running program, you probably know that running is great for your cardiovascular fitness and overall health. But you might wonder if running gives you muscular, or runner's legs. The answer is a qualified yes — because running primarily uses your legs, you will develop sport-specific muscles over time.
By understanding the effect of running on each of your main leg muscle groups, you can tailor your fitness plan to build muscle where you want it.
How Do Your Muscles Get Stronger in the First Place?
No matter what type of exercise you do, some degree of resistance is being placed on your muscles when you work out. When a higher level of resistance than usual is placed on your body — like during a workout as opposed to doing regular daily tasks — this triggers your muscles to grow.
Specifically, this added resistance causes damage to and breaks down the proteins in your muscle fibers (more on that below). To counteract this process, your body makes new muscle proteins to repair this damage. This is called muscle protein synthesis, according to the International Sports Sciences Association (ISSA).
Fast- Twitch vs. Slow-Twitch Muscles
Depending on whether you are jogging or sprinting, you utilize one of two types of muscle fiber: slow-twitch or fast-twitch. Long-distance running uses slow-twitch fibers, which are not as strong as fast-twitch but have a good oxygen supply and can work for long periods of time without tiring.
By contrast, fast-twitch muscle is stronger but tires quickly, so it works when you are sprinting. The bulging leg muscles of sprinters are due to more fast-twitch muscles, while the lean legs of distance runners are composed of mostly slow-twitch muscles.
What Muscles Does Running Build?
The quadriceps is one of the largest muscle groups in your body. Composed of four muscles, your quads lift and extend the knee while running. In a fast run, the quads engage more strongly to lift your knee higher and thus extend your stride, which is why sprinters have such powerful quadriceps.
Endurance running, on the other hand, makes fewer demands on the quadriceps, because it is a forward motion driven from the hip.
Your calf muscles play an essential role in propelling you each step forward, meaning that you will develop muscular, toned calves with regular running. However, excessive speedwork, or sprinting at the end of runs, can lead to injury as you push off from your toes, which stresses the calf.
Running up hills, doing plyometric drills (like hopping and skipping) and performing calf-specific strength exercises (like calf raises) will all build further strength in this muscle group.
The hamstrings are the prime mover in long-distance running. The hamstrings get very strong with regular running but they can also become tight, which can cause injuries through muscular imbalance. That's why you should work all the major muscles of the lower body together — the glutes, hamstrings and quads —to prevent imbalance, according to Harvard Health Publishing.
By varying your running training you can develop muscular legs safely. For example, if you're a long-distance runner, include some sprint work or hill training to improve your quad and calf strength; if you're a sprinter, do some long runs to keep your hamstrings strong and flexible.
Your glutes, the largest muscle group in your body, helps propel you forward as you run, per Hone Health. They work together to stabilize your pelvis, shift your weight from side to side and extend your hips as you push off the ground.
How Runners Can Build Leg Muscle
You may only think leg exercises like squats and deadlifts can build muscle in your lower body. While this is true, there are actually a few other ways you can build leg muscle as a runner.
1. Running-Specific Workouts
Incorporating high-intensity interval training (HIIT), like sprint intervals, into your routine can help you build leg muscle. According to a small January 2017 study in the International Journal of Exercise Science, runners who did this type of training over 10 weeks had 10 percent larger quads than runners who didn't do this type of training.
Here's a sample sprint interval workout LIVESTRONG.com has previously recommended. It's important to not do this type of training more than 2 to 3 times per week, per the National Academy of Sports Medicine (NASM), because it could lead to injury.
2. Leg-Strengthening Exercises
Not only will strength exercises build lower-body muscle, but they'll also help prevent injury and improve your running economy. Here are four of the best strength-training exercises for runners.
1. Body-Weight Squat
- Stand tall with your feet hip-width apart and brace your core. Focus on keeping your feet rooted into the ground and your core tight the entire time.
- Extend your arms out in front of you and slowly bend your knees as you push your hips back to lower toward the floor. Focus on lowering your body as if you were going to sit on a chair.
- Lower down as far as comfortable, or until your thighs are parallel with the floor.
- Pause for a moment at the bottom of your squat.
- On an exhale, reverse the motion by pressing through your heels to return to standing. As you stand, lower your arms back to your sides.
2. Romanian Deadlift With Barbell
- Set up a barbell in a power rack just below hip height. Stand in front of the bar with your feet shoulder-width apart. Grab onto the bar with straight arms. Your hands should be beneath your shoulders and just outside your legs.
- Take the bar out of the rack by driving your legs into the floor and standing upright. Take two small steps back away from the rack.
- Initiate the movement by bending your knees slightly. Keep your chest tall as you reach your hips back behind you. You should feel a stretch in your hamstrings. Keep the barbell right against your legs.
- Reach your hips back as far as you can without rounding your low back.
- Finish the rep by driving your legs into the ground and returning to the starting position.
- When you're finished with your set, walk forward with the bar and return it to the power rack.
3. Forward Lunge
- Stand upright with both feet together.
- Step forward with one foot in front of your body. Take a big enough step that your front knee forms a 90-degree angle. Land with your front foot flat on the floor and grab the ground with your toes. Drive your back toes into the ground.
- Bend both knees and drop toward the floor with control. Keep lowering until your back knee is about an inch off the ground (or as low as comfortable). Keep your chest tall, but some forward lean is OK.
- Finish the rep by pushing off your front foot to return back to standing.
4. Calf Raise
- Stand tall on a flat surface with your shoulders down and back, arms by your side and toes pointed straight ahead. (For seated version, sit with hands on thighs.)
- Lift your heels off the floor to flex your calf muscle.
- Pause for a count, then slowly lower your heels back down.
3. Proper Nutrition
Getting enough protein is especially important in helping build and repair your muscles after a workout. And, athletes like runners need more of this macronutrient than average person, according to a 2019 statement from the International Association of Athletics Federations (IAAF).
If you want to maintain or gain muscle mass, you should aim to consume 1.6 to 2.4 grams of protein per kilogram of body weight per day (0.7 to 1.1 grams per pound). For a 150-pound person, that means eating 105 grams to 165 grams of protein per day.
4. Enough Recovery
Your muscles need rest in order to properly repair themselves to grow bigger and stronger. Plus, overworking the same muscles too much may lead to injury. Take at least 1 recovery day per week, according to the American Trail Running Association (ATRA).
The ATRA recommends doing mobility exercises or light cardio. Any of your favorite low-impact activities — like walking, yoga, swimming, cycling or even kayaking and stand-up paddleboarding — are fair game as long as you take it easy.
- Harvard Health Publishing: "Are Your Hamstrings Working Double Duty?"
- ISSA: "Muscle Protein Synthesis: What It Is and How to Maximize It"
- International Journal of Exercise Science: "The Effect of High Intensity Interval Run Training on Cross-sectional Area of the Vastus Lateralis in Untrained College Students"
- NASM: "UTILIZING SPRINT INTERVAL TRAINING FOR WEIGHT LOSS"
- ATRA: "HOW TO GET THE MOST OUT OF YOUR REST DAYS"
- IAAF: "International Association of Athletics Federations Consensus Statement 2019: Nutrition for Athletics"
- Hone Health: "The Exact Muscles You Activate When Running—and How to Injury-Proof Them"
- “Galloway's Book on Running”; Jeff Galloway; 2002