Does Running Build Leg Muscle? 

Table of Contents

• Muscles Worked While Running
• Does Running Build Leg Muscle? 
• Running For Muscle Mass vs. Strength
• Is Running a Better Way to Build Leg Muscles?
• Running vs. Weightlifting for Building Leg Muscles
• Bottom Line

Sure, running gets the heart and lungs pumping and can seriously burn calories, but does running build leg muscle? 

Running strengthens several major leg muscle groups, but maybe isn’t the best way to build leg muscle. 

Below, we explore:

• Muscles worked when running
• The benefits of running
• How running compares with other muscle-building exercises 
• Why lifting weights could help sculpt stronger, leaner legs 
• Deciding which is right for you. 

Let’s get into it!

Muscles Worked While Running

Running recruits major muscle groups in your legs and lower body, but it also gets support from your core, back, and arm muscles, making it an efficient full-body workout. 

Here are some of the muscle groups that work when you run:

Primary Muscles Worked:

• Glutes 
• Quadriceps 
• Hamstrings
• Calves

Secondary Muscles Worked:

• Shoulders
• Arms 
• Back

Stabilization Muscles Worked 

• Abdominals/ core muscles
• Hip flexors
• Glutes

What Are Runner’s Legs?

When discussing muscles worked while running, it’s worth mentioning the term “runner’s legs.”

When people talk about “runner’s legs,” they usually refer to how a runner’s legs might look – lean, toned, and powerful due to the consistent and strenuous exercise that running involves. 

Sometimes, the term might also be used to discuss certain issues runners often face, like “runner’s knee,” a common overuse injury in the knee joint. 

But it’s important to note that “runner’s legs” isn’t an official medical term. It’s more of a casual phrase you might hear among runners or fitness enthusiasts.

Does Running Build Leg Muscle?

Before we answer whether running can build muscle, let’s briefly cover how to build muscle — a process known as hypertrophy. 

Exercise acts as a stressor for muscles, creating teeny microtears in the muscle fibers and causing damage (in a good way!). 

A mixture of recovery, sleep, and refueling (think diet and protein) helps them rebuild and grow. 

But your ability to grow muscle depends on several factors like duration, frequency, and intensity of your running workouts, lifestyle factors like sleep, diet and stress, and genetics. 

Your muscles can’t grow unless met with a challenge that forces them to adapt — in other words, loading.

Consider the type of running workouts you do — the terrain of your runs, duration, frequency, and intensity. 

Someone who runs several times a week will build leg muscle more than someone who runs once a week. 

A person who runs slowly on flat ground won’t develop as much strength or lean mass as someone who favors hill training or high-intensity interval sprints. 

Research backs this up — studies show that long-distance runners have higher muscle protein breakdown (MPB) and could actually lose muscle or inhibit muscle growth. [1] 

If the body doesn’t have ample fat or carbs as a fuel source, the body may resort to stored protein in the muscles as a last resort. 

Shorter duration and higher-intensity efforts stimulate muscle growth, as your body must work harder against resistance and demand, meaning this type of running builds leg muscles.

Does Running Make Your Legs Bigger?

Running does build leg muscles, however, building strength and muscle aren’t mutually exclusive — strength refers to the number of fibers packed in the muscle, whereas growth means an increase in muscle fiber size. 

Let’s compare sprinters and endurance runners as an example. Sure, sprinters are built for the sport, but they also train for the muscle types they use. 

Sprinters require larger, more powerful muscles to fuel short, explosive runs. Short interval sessions like sprints and uphill runs help build leg muscle by increasing stimulus and load on the body. 

Training like this shifts the emphasis on the muscles worked — hill training hits the glutes and hamstrings more, whereas flat or downhill running is quad-dominant. It’s a great way to out-train muscular imbalances.

Long-distance runners prioritize muscular endurance and have much lighter frames. If you favor steady-state running, you’re unlikely to have very muscular-looking legs, but they’ll be strong and built to last. 

Running For Muscle Mass vs. Strength

As we mentioned, running for strength differs from running for muscle growth. 

Higher intensity or uphill efforts that require explosive power are more likely to create the resistance needed to build leg muscle. 

If you want to develop muscular endurance for long-distance, then steady-state efforts are your best bet. 

Either way, you need to build robust legs to fuel your runs. 

Sprinters will focus on building explosive strength, whereas long-distance runners build muscular stamina; this determines the muscle fibers you recruit. 

Long-distance runners mainly activate the slow-twitch muscle fibers, whereas sprinters switch to fast-twitch muscle fibers to produce maximum exertion as they run. 

Is Running a Better Way to Build Leg Muscles?

There are pros and cons to running. 

Taking a jog improves cardio fitness, strengthens muscles, and builds mental resilience. 

Cons? 

It has a high impact on your joints, and compared with other exercise types like HIIT classes, wild swimming, climbing, boxing, and gymnastics, running isn’t the best way to build leg muscles. 

Your best bet? Include strength training in your running program. 

Running vs. Weightlifting for Building Leg Muscles

Traditional resistance training and strength exercises are the most effective ways to build leg muscles. 

You could use your body weight — a method called calisthenics — or add machines, dumbbells, barbells, resistance bands, or kettlebells to your training program. 

Lower-body compound exercises are multi-joint, multi-muscle strength exercises that target the muscles active during running. 

Here are some compound strength exercises that build leg muscle:

• Squats
• Deadlifts
• Lunges
• Glute bridges
• Step-ups 
• Calf raises 
• Lateral lunges
• Banded crab walks
• Banded donkey kicks
• Skipping.

The research shows that resistance training builds strength and muscle mass, develops power, prevents injury, and improves athletic performance. [2]

Should You Combine Running With Weightlifting?

Runners who incorporate strength training witness marked improvements in their performance metrics. 

Enhancements in VO2 max, a measure of maximal oxygen uptake, indicate greater cardiovascular fitness and aerobic endurance. 

This means runners can run harder and longer. 

Additionally, they experience improvements in running economy, meaning they use energy more efficiently at a given pace. 

Finally, strength training boosts maximal strength markers, increasing muscle power and reducing injury risk. 

In essence, combining strength training with regular runs offers runners optimized performance and greater injury resilience. [3] 

Many strength and conditioning programs target runners for this reason and focus on single-leg exercises, hip hinge movement, or balance and stability drills to address imbalances in opposing muscle groups.  

But if you’re determined to stick with running to build leg muscles, add intensity. 

The studies tell us that muscle-building abilities are associated with quicker, shorter distances and support increased muscle size after high-intensity running several times a week. [4] [5]

You could include several high-intensity sessions per week, like strength training, hill sprints, and interval sessions. 

But consider a personal trainer or running coach who can develop a training plan specific to your needs. 

Remember to include a warm-up (here’s a 10-minute leg day warm-up we swear by) and recover for at least 24-48 hours after running to allow muscles to rebuild and grow. 

Bottom Line

So, does running build leg muscles? Here’s what we learned:

• Running strengthens key muscle groups like the glutes, hip flexors, quads, hamstrings, core muscles, and calves and also targets the arms, shoulders, and back muscles.
• To build leg muscle while running, focus on shorter, higher-intensity efforts and uphill training to increase load and demand.
• Long-distance runs are more likely to break down muscle tissue, especially without refueling with a proper nutrition plan.
• To help build leg muscle, include strength training exercises in your running routine several times a week that target the muscles used when running.

And remember — 

Dial into your nutrition plan to build muscle while running rather than lose it. 

If you’re in a caloric deficit, reducing carb intake or running in a fasted state, you could risk burning protein stored in the muscle tissues. 

Focus on protein, carbs and good fats, and replenish sources after a run. 

Long-distance runners will need a higher intake of carb sources, but to build muscle, you’ll need to consume enough protein after a workout, which is essential for building and repairing muscle.