Running engages your core and the muscles of your hips, glutes, quadriceps, hamstrings, and calves. The degree of engagement depends on your speed and terrain.

While running is a whole-body workout, you primarily use your core and lower body muscles.

It’s important to keep these key muscles strong and healthy since they’re responsible for stability, proper form, and spinal alignment — all of which help you perform at your highest capacity with maximum efficiency.

Understanding how each muscle works may help you improve your running form, technique, and performance. Keeping these muscles balanced and working together in harmony will also help prevent injury.

Read on to take a closer look at the muscles used when running.

A strong, stable core is the foundation of a healthy body and most movements and activities. Located in your torso and pelvis, your core muscles connect your upper body to your lower body.

A strong core helps to maintain proper posture, balance, and form while running. It can also help to properly align your spine, pelvis, and lower body.

Strong abdominals help your body stay upright and reduce the shock impact on your back. A weak core may cause you to compensate with other muscles, which can lead to injury.

Your hip flexor muscles are located at the front of your hips, right above your thighs. They connect your thighbone, to your low back, hips, and groin. The hip flexors help with pelvic and spinal stabilization.

While running, you use these muscles when you flex your knee and leg up toward your body, as well as when you move your legs forward.

To ensure mobility, it’s important to maintain strength and flexibility in your hip flexors. Tightness in your hip flexors can compromise the action of your glutes, which can lead to compensation in other areas and even injury.

Your gluteal muscles are located in your buttocks. The strength of these muscles plays a vital role in running, as they propel you forward and help you run faster. The glutes also help to maintain stability in your torso so you can maintain proper posture.

As the main muscles responsible for hip extension, they also help to stabilize and strengthen your hips. This helps to ensure alignment in your spine, knees, and feet.

The quadriceps are a group of four long muscles located on the front of your thigh. In running, they extend your knee and propel you forward. The energy that begins in your quads is transferred into the hamstrings.

Connected to the kneecap, the quads are responsible for straightening and stabilizing your knees as you run.

The hamstrings are located on the back of the thigh between the hips and knees. They’re responsible for hip extension and knee flexion. The hamstrings also help with thigh extension as you move your upper leg backward.

You activate your hamstrings to push off the ground with each step and to maintain a bend in your knee, which helps prevent hyperextension. Bending your knees to raise your feet toward your butt helps to drive you forward.

To maintain maximum efficiency as a runner, you must have strong, flexible hamstrings. Otherwise, your form suffers, and your risk of pain and injury increases.

Many people have weak hamstrings in comparison to quadriceps, which can lead to overcompensation and imbalances in your hips, knees, and overall stride.

Your calf muscles are located on the back of your lower leg. You use these muscles each time you push off and raise your leg to propel forward.

The calf muscles are also involved in extending and flexing your foot each time your foot strikes and pushes off again. They’re responsible for reducing the shock of impact as you land, helping with balance, and ankle mobility.

Running uphill or downhill requires you to use slightly different form since you’re working your muscles differently. When running hills in either direction, make a point to align your torso over your pelvis.

Running downhill

Running downhill is easier on your cardiac muscles. But your hip, leg, and ankle muscles must work harder, especially your hip extensors, quads, and knees.

Running downhill may cause you to put too much pressure on your shinbones, which can lead to shin splints. You naturally use more of a heel-foot strike, which helps to slow down your forward movement. Be mindful not to lean your upper body too far back.

Running uphill

When you run uphill, you have to work harder and activate more leg muscles to overcome gravity. Compared with running on a flat surface, you activate the vastus muscles of your quadriceps more and your hamstrings less.

Running on an upward incline requires you to change to a mid- or forefoot strike. This type of impact puts more pressure on your calves and ankles, but it also makes it easier to push off from the ground. This is because some of the energy from the shock is absorbed by your calves, which provides power as you propel forward.

When running uphill, focus on using your hip muscles to propel forward and fully extend your leg behind you. Avoid leaning too far forward when you run uphill, as this can make it more difficult to engage your hip flexors to raise your knee. Running uphill can have a negative impact on your balance and push-off.

Running also works your tendons and ligaments, which help to absorb some of the impact. Tendons are connective tissues that connect your bones to muscles, aiding in smoother movement and shock absorption.

Ligaments are connective tissues that bind your bones to each other. By absorbing some of the stress and impact from running, they help to make your body stable and prevent too much movement between bones.

According to most doctors, you need to warm up before you begin working out for at least 5 minutes before moving on to stretching. Strenuous exercise such as running can shorten and tighten your muscles, which can cause reduced mobility and limit your range of motion.

It’s important to keep your muscles loose, flexible, and supple to prevent discomfort, pain, and injury.

Check out these stretches that are perfect for runners.

It’s important to understand the primary muscles you use when running, as well as the mechanics of the movements.

Adding a strength training and stretching routine to your fitness program that focuses on targeting the key running muscles will help your muscles work together so you can run at your optimum and most efficient level.