Does Running Build Leg Muscle?

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.

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).

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.

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.

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.

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.

• 5-minute warmup of brisk walking or easy jogging
• 30-second sprint at 80 percent (or more) of your max effort
• 90-second recovery walk
• Repeat this 2-minute circuit 5 times
• 5-minute cooldown of walking and stretching

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

‌2. Romanian Deadlift With Barbell‌

‌3. Forward Lunge‌

‌4. Calf Raise‌

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.

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.