Treadmills are fantastic pieces of cardio equipment. They let you run from the comfort of your own home or even in the gym, whichever you prefer, and they offer you one of the best cardio workouts that you can get. Running has been proven to be one of the highest calorie-burning exercises out there, so it makes sense that they are famous for it.

One question that does crop up because of this, though, is how effective they are at building up the muscles in your legs. They are entirely leg focused after all. When it comes to running and even general cardio exercising, you might find that there is more to it than meets the eye, especially when building muscle is involved.

Exercise mechanics

woman running on treadmill at the gym

To be able to answer whether treadmills build leg muscles, you need to look at what exactly is going on when you run. Ultimately, you’re pushing your whole body forward by explosively contracting muscles in your leg. This contraction is pushing your whole-body forwards at a pretty great speed in rapid succession, so it’s a lot of work for you to be doing. You’re also keeping yourself balanced as you alternate legs and pick up speed, so there’s a lot more to it than you might have thought.

Muscles used

Now we need to look at the specific muscles that you’re using to make the whole thing work. The smaller muscles will, of course, be doing their part. These are the muscles in your feet and throughout the rest of your body. However, it’s the big hitters in your leg that are generating the driving force behind you. Your quads, hamstrings and calves are all working together to move different areas of your leg in complementary ways. As this happens, they also work on moving your entire body weight.

The effects

Now that we know the mechanics, it’s time to look at the implications. It would make sense that a treadmill builds leg muscle, but there’s more to it. Technically, yes, as you start running, your muscles are going to be working harder than they are used to, and they will build up to be able to do it easier next time. That’s just what the human body does. Muscle growth relies on increasing stress to keep these changes happening. Running on a treadmill alone will eventually lead your legs to a standstill in growth.


Although your leg muscles won’t just grow and grow and grow, they will get stronger. Remember, size doesn’t always increase strength. Your performance will continue to improve as you keep on running more, and you better your technique. You’ll be burning a high number of calories while you are using your treadmill, which is always a huge plus. Your muscle definition will improve as you’re burning more fat from the exercises, and you will tone up your legs if you adjust your diet alongside it.

Before beginning any exercise or nutrition program, consult your physician, doctor or other professional. This is especially important for individuals over the age of 35 or persons with pre-existing health problems. assumes no responsibility for personal injury or property damage sustained using our advice.

If you experience dizziness, nausea, chest pain, or any other abnormal symptoms, stop the workout at once and consult a physician or doctor immediately.