Does Running Build Leg Muscle? Here’s What to Know if You Want to Swap Leg Day for a Run

All the miles of training helps strengthen the lower body, namely the quads, glutes, hamstrings, and calves.

But, is running enough to build leg muscle? What happens if you want to swap leg day in the gym for a run? Will your legs still get strong? To find out, we spoke to Mindy Solkin, a USATF level 2 certified running coach and founder of The Running Center.

How does running compare to resistance training?

Although running does strengthen the muscles, it’s not necessarily the best way to build leg muscle. Traditional resistance training exercises like squats, deadlifts, step-ups, and glute bridges are generally more effective, especially if you use dumbbells or other weights. That’s because running only uses your bodyweight and the additional load when lifting weights helps better overload the muscles—which is what stimulates muscle protein synthesis, the process of muscle growth.

Because running is one repetitive motion that you perform over and over again, it can also create imbalanced strength, with certain muscles putting in overtime and others, well, not. Because of this, Solkin says you should balance your running workouts with strength training exercises that work the opposing muscle groups so you can train all your leg muscles.

“It’s important to strengthen opposing muscles in synergy with each other,” she explains. “When doing calf raises for the gastrocnemius [calf] muscle, the runner should also do exercises for the anterior tibialis muscle—the front of the lower leg—to create more balanced strength on the lower leg to prevent injuries.”

If you’re wondering if just running will make you strong enough, the answer depends on your goal. In other words, strong enough for what? Strong enough to run a marathon? Strong enough to squat 100 pounds? Strong enough to safely perform everyday activities?

Will running alone strengthen your legs?

If you’re wondering if just running will make you strong enough, the answer depends on your goal. In other words, strong enough for what? Strong enough to run a marathon? Strong enough to squat 100 pounds? Strong enough to safely perform everyday activities?

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Also know that the amount of leg strength you build by running depends on variables like the terrain you run on, the length and frequency of your runs, your speed, and your weight. “A person who runs three times per week on a flat course at a slow pace will not have as much leg strength as a person who runs six times per week on hills at a fast pace,” Solkin says.

The type of running workouts you do will also influence whether your training will primarily increase muscular endurance or strength/power. “A marathon runner, who runs for multiple hours, has stamina, which is the result of strength multiplied by time,” Solkin says. “A sprinter, who only runs for seconds, produces power, which is the ability to exert maximum muscular contraction instantly in an explosive burst of movements.” (Here's exactly why sprinting builds muscle.)

No matter what kind of running you’re doing, though, strength training exercises will help you have a more powerful stride¹ and may help prevent injuries and improve performance². Your strength workouts don’t even have to be particularly intense. For example, Solkin created Runditioning™, a strength and conditioning exercise program for runners. “Many of the exercises are done while standing on a balance board on one leg, while the other leg swings in a forward/backward stride, mimicking the running movement. I call this ‘running on one leg,’ which results in having balance, stability, and strength on each leg, independent of each other.”

One more thing: While runners put a lot of stock in the strength of their legs, you also shouldn’t neglect the rest of your body. “Remember that although the legs and the core muscles do most of the work, it's important to strengthen your arms, too,” Solkin says. “Having strong arms will help your form and will also help you run up hills more efficiently, taking some of the pressure off the legs.”

FAQ

Does running work every leg muscle?

Running works every major muscle in your legs, according to Hone Health. This includes your glutes (butt), quads (front of thighs), hamstrings (back of thighs), hip flexors (front of upper thighs), calves (back of legs), and feet.

How long should I run to see leg-building results?

According to a 2014 review in Exercise and Sport Sciences Reviews, running for 30 to 45 minutes, four to five days a week is comparable to a traditional strength-training workout when it comes to getting enough high-volume, low-load muscle contractions.

Is running enough for a legs workout?

The answer to this question depends on your goals and what you define to be “enough.” Yes, running works the muscles in your legs, but according to the International Sports Sciences Association (ISSA), it's still important to incorporate leg workouts into your fitness routine for other reasons. These include running faster, running farther, and preventing injury. If you're not sure which exercises to start with, the ISSA recommends the following:

• Forward lunges
• Side lunges
• Squats
• Sumo squats
• Split squats
• Single-leg deadlifts
• Calf raises