Muscles Worked by a Treadmill: The Complete Guide

Treadmill? More like trea-don’t for most people.

Seriously though, we know it’s not the most exciting workout out there. But if you’re stuck indoors, it’s a solid way to get your cardio in. Plus, it actually exercises more than just your legs – it works your whole lower body, including your glutes, hips, and…yes, your arms.

How does it do that?

We’ve put together a list of the muscles most commonly worked by treadmills, separated into three categories: running, walking, and incline. This structure will help you better understand which muscles you’re working when using this popular exercise equipment.

That’s how you can ultimately build effective workouts. And to help you get started, you can read a weekly sample workout in the conclusion section.

Keep reading below!

Muscles Worked Running

Running activates your muscles differently than walking. Running at no incline is also different from using the treadmill’s tilt.

So in this section, we’ll refer to running at zero incline.

In this case, your muscles must execute more explosive movements, leading to:

More pressure on your bones and joints
Faster movement of your muscles
More energy expended
Less control over resistance-like movements

Here’s what that means for your muscles worked:

Muscles in Your Soles and Ankles

The soles of your feet are essential, even if you don’t realize that. Nobody actively goes to the gym to work out their soles or thinks about their socks as pump covers.

However:

Strong soles and ankles stabilize your gait.
Weak muscles in these areas lead to unbalances in your hips, hunching, and a myriad of other health issues. As a result, you’ll suffer from chronic back, neck, and hip pain.

Running will activate the muscles in these areas because they must work to stabilize your body with each step. Here are the primary muscles worked:

Extensor hallucis longus
Tibialis anterior
Flexor digitorum longus
Gastrocnemius
Soleus
Plantarflexors
Dorsiflexors
Evertors
Invertors

Muscles in Your Calves

Your calves are some of the most important muscles when running. That’s because they work to push your body forward and up with each step.

The main muscle worked in your calves is the gastrocnemius. This muscle is responsible for plantarflexion, which is the movement that points your toes downward.

The gastrocnemius is a two-part muscle, with the inner portion (medial head) and the outer part (lateral head) working together. The medial head is responsible for plantarflexion, while the lateral head works to stabilize your ankle.

Muscles in Your Thighs

Your thighs are some of the largest muscles in your body, so it’s no surprise they’re worked when running.

The primary muscle worked in your thighs is the quadriceps. This muscle is responsible for extending your knee, which is necessary for running. The quadriceps is a four-part muscle, with each portion working together to extend the knee. These portions are the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.

Running also engages your hamstrings because these muscles elongate and stabilize your leg with each exploding forward movement. However, if you’re running at zero incline, your quads will work harder than your hamstrings.

Running activates your outer and inner thighs, but not as much as quads. These muscles are part of your thighs but act as supporting muscle groups while running. Although they elongate and contract with each step, they will do less work than your quads.

Muscles in Your Butt

Everyone wants to know if running will give them a better-looking butt. Of course, that means different things to different people. Some like bigger bums; others wish for smaller and tighter buttocks.

Here’s the deal:

Running will activate your glutes, but you won’t feel the burn as much as with incline walking/running. The reason is running has you moving faster instead of consciously, actively placing resistance on your bum.

And that resistance is what makes your glutes grow.

Muscles in Your Back

You use your back muscles when running, even though you might not feel it. These muscles work to stabilize your spine and prevent excessive movement.

The main muscle worked in your back is the erector spinae. This muscle is responsible for keeping your spine upright and stable. The erector spinae is a three-part muscle, with each part working to stabilize a different section of your spine. These parts are the iliocostalis, longissimus, and spinalis.

You also use the gluteus medius and gluteus minimus. These muscles in your rear stabilize your pelvis and hips while running.

Muscles in Your Chest

Your chest muscles don’t do much when running. However, they are engaged to a small degree to keep your shoulders and arms stable.

The primary muscle worked in your chest is the pectoralis major. This muscle is responsible for keeping your shoulders down and stabilizing your arm movement. The pectoralis major is a two-part muscle, with each part working to stabilize a different section of your shoulder. These parts are the clavicular head and the sternocostal head.

You also use the trapezius and latissimus dorsi. These muscles in your upper back stabilize your shoulders.

Don’t let that discourage you, though. There’s a way (well, three ways) to get more work out of your chest muscles when you’re running:

Keep your posture strong, squeezing your pecs, lats, and arms. That way, these muscles stay contracted and grow stronger.

You can also run with small free weights in your hands. However, we don’t recommend more than 1-2 pounds, or your shoulders may overstretch forwards, and you may be injured. It’s also crucial not to bend your wrists when you’re holding these weights, or again, you may hurt those wrists.

Use wrist weights that wrap around your wrists. That way, you avoid over-squeezing your fingers and injuring your wrists. You still have to be careful not to flail your shoulders or squeeze them up to your ears.

Muscles in Your Arms

Your arms don’t do much when running, but they are engaged to a small degree to help you maintain balance.

The primary muscle worked in your arms is the biceps brachii. This muscle is responsible for keeping your elbows stable and helping you maintain balance. The biceps brachii is a two-part muscle, with each part working to stabilize a different section of your elbow. These parts are the short head and the long head.

You also use the deltoids and triceps brachii. These muscles in your shoulders stabilize your arms.

Again, don’t let that discourage you. You can build more arm strength while running if you:

Keep your posture strong, squeezing your biceps and triceps.
Hold onto free weights or use wrist weights.

Muscles in Your Core

Your core muscles are engaged to a small degree when running. These muscles work to stabilize your spine and pelvis.

The main muscle worked in your core is the rectus abdominis.

This muscle is responsible for keeping your spine stable and your pelvis level. The rectus abdominis is a two-part muscle, with each part working to stabilize a different section of your spine. These parts are the upper abs and the lower abs.

You can feel quite a burn in your abs after a good run (that’s why many newbies get runner’s diarrhea if they push themselves too much). To increase that burn, remember to keep:

Your posture straight
Your abs contracted

Bonus: How to get more work from your obliques

While your obliques are supporting muscles during your run, you can push them to work harder. The secret is keeping them contracted and letting your torso twist more.

Warning: Keep your hips straight forward to avoid injury, and don’t flail your shoulder or arms around.