Treadmills are fantastic piece of cardio equipment and running is one of the very forms of exercise - but will a treadmill build leg muscle?

Treadmills allow you to run from the comfort of your own home (or in the gym, whichever you prefer), and they offer 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, after all.

One question that does crop up often is how effective a treadmill is at building up the muscles in your legs. They are entirely leg focused, after all. When it comes to running and cardio in general, you'll find that there's more to it than meets the eye...


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  1. How does running use my leg muscles?
  2. Will a treadmill build leg muscle?

How does running use my leg muscles?

woman running on treadmill at the gym

Let's understand 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 body forward at great speed in rapid succession - 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, which requires even more strength, stamina and control.

Now we need to look at the specific muscles that we use when we run. The smaller muscles will, of course, be playing their part, including the muscles in your feet. 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 work on moving your entire body weight.

Now that we know the mechanics of running, it’s time to look at the implications. It would make sense that using a treadmill builds leg muscle, but there’s more to it than meets the eye. Technically, yes: when you start running, your muscles start working harder than they are used to, and the more you run, the more your muscles build up to make it easier next time. That's the way the human body works. But muscle growth relies on increasing stress to keep these changes happening, so when you reach your peak of stress whilst running a treadmill, there'll be a standstill in muscle growth.


Will a treadmill build leg muscle?

So, will a treadmill build leg muscle? Although your leg muscles can't continue to grow and grow and grow with just treadmill running, they will continue 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 also be burning a high number of calories while you are using your treadmill, so your muscle definition will improve as you’re burning more fat from the exercise.


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. Exercise.co.uk 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.