I did a treadmill run every day for two weeks, and this is what happened

My speed improved and I trained harder, but I was always tempted to head outside instead

Lucy Gornall exercising on treadmill at the gym
(Image credit: Lucy Gornall)

Running is a great way to improve your cardio fitness and overall health. Personally, I find running clears my head and helps me to overcome stress. It also helps to maintain a healthy weight. 

I mix up my runs: sometimes I run outdoors, other times I fancy a treadmill run. So, I decided to take on a two-week treadmill challenge to find out how I felt (or how my legs felt!) and if I would notice any benefits from everyday indoor running.

I don't have one of the best treadmills at home, so I used the gym's machine instead. The beauty of this cardio machine is that it encourages you to keep up with the speed you’ve set.

After taking on the two-week program, I'd challenged my legs and improved my speed, though it wasn't all upsides. I missed the outdoors and it played with my posture. But would I do it all over again? Absolutely. 

My speed improved

At the beginning of my two weeks, I was starting my runs at a comfortable 8.3mph on the treadmill. However, by the end of the two weeks my comfortable starting speed was 8.6mph. Also, I managed to maintain higher speeds for longer than if I was running outside. 

The beauty of working your speed on a treadmill is that, when you’ve set your speed, you just have to keep up. It’s easier than being outside and having to propel your body forward yourself. 

This treadmill challenge was only for two weeks but it still improved my outdoor running times. I use an Apple Watch to track every second of movement that I do, and I noticed that my average speed was up slightly when I ran outside at the end of my two weeks. 

The treadmill is great for zone 2 running

If you want to hone in on your fitness, as well as your running speed, you need to get to grips with zone 2 training. This training improves your aerobic capacity, in turn helping to improve your endurance.

Essentially, you need to be running at such a speed that your heart rate stays in zone 2, so a heart rate tracker is essential. A zone 2 heart rate tends to be about 65% of your maximum heart rate; so you could be running at a conversational speed. 

Now, if you’re like me, when you get outside for a run you fly off and aren't going at a speed where you’d be able to chat comfortably. The treadmill, however, allowed me to find that slow zone 2 speed and, yet again, I was forced to stay on this speed. 

Lucy Gornall on a treadmill at the gym

(Image credit: Lucy Gornall)

My body felt tense

You know when you allow yourself zero time to relax and end up unknowingly walking around with a bit of a hunch, your back feeling tight and your posture off? 

Running continuously had a role to play in the feelings of soreness which plagued my shoulders and back. If you give the challenge a try and find the same, it's probably a good idea to do a Pilates for posture routine too! 

Plus, I wouldn’t usually recommend running every day: it’s a high-impact exercise that places pressure on the joints. For me, two weeks of treadmill-pounding caused my runner’s knee to flare up. I was icing and elevating my right knee frequently.

I didn't always stick to the treadmill

The treadmill can become boring, so I had to take things outdoors for some road running. As I’m currently training for a marathon, my longer runs, around 18 miles, are much better done outside.

If you can run that far on a treadmill, I salute you because I would find that to be the dullest run of my life. Plus, there are loads of benefits to outdoor exercise, from improved mood to better sleep. 

I had to strengthen my knees

With all this treadmill running wreaking havoc on my knees, and every other lower body joint for that matter, I enlisted the help of my physio, Tim. He programmed a resistance band rehab routine and I stuck to it for the duration of this challenge.

Various banded exercises, done slowly, were the key to helping avoid knee pain. Yes, physio exercises are dull as dishwater, but they work. If you’re ever given rehab exercises to help heal and lessen the pain in a particular area of your body, make sure you do them.

I did a treadmill run every day for two weeks: the verdict

For two weeks, I’d do this challenge again. The treadmill helped me to find my stride, improve my speed and pushed me into doing zone 2 training. However, if your body isn’t conditioned to exercising every day, then make sure you factor in rest days.

You will give yourself an injury if you hammer your body every day. Running is a high-impact exercise and our joints need care if we want to keep moving comfortably. If you're still eager to move, you could try this active recovery day workout instead. 

But if you do feel the effects of delayed-onset muscle soreness (DOMS), it's important to give your body the protein it needs to repair the tiny tears in your muscle fibers caused by your training. 

Although you can get most of your allowance from your diet, the best protein powders for weight loss are ideal if you need a top-up and are low in sugar and fat to help you hit your fitness goals. 

Lucy Gornall

Lucy is a freelance journalist specializing in health, fitness and lifestyle. She was previously the Health and Fitness Editor across various women's magazines, including Woman&Home, Woman and Woman’s Own as well as Editor of Feel Good You. She has also previously written for titles including Now, Look, Cosmopolitan, GQ, Red and The Sun. 

She lives and breathes all things fitness; working out every morning with a mix of running, weights, boxing and long walks. Lucy is a Level 3 personal trainer and teaches classes at various London studios. Plus, she's pre- and post-natal trained and helps new mums get back into fitness after the birth of their baby. Lucy claims that good sleep, plenty of food and a healthy gut (seriously, it's an obsession) are the key to maintaining energy and exercising efficiently. Saying this, she's partial to many classes of champagne and tequila on the rocks whilst out with her friends.