Why Do I Run Slower On A Treadmill? (6 Reasons)

Treadmill Running

Sakdinon Kadchiangsaen/Shutterstock.com

By Simon Gould

If you run outside normally then the treadmill feels very different. Outside you have all the terrain differences and practically every foot fall is different especially if you run on trails. There's usually some nice wind to slow you down and cool you down too. Many runners report they go slower on a treadmill, is this the case or is there something else causing this?

Why running on a treadmill should be easier

First of all the lovely cushioned belt that eases every foot fall and propels every step. Outside you could be running on tough concrete and there is no give. You get no return of energy back when you want to push off from the toes. With a treadmill you can specify your speed so you can't fail to make sure you're quicker by setting a quicker speed than what you do outside.

There is no wind resistance to slow you down. That is the reason given for why the treadmill is scientifically easier to run than outside. That research says you use less energy on a treadmill because of the wind resistance. They advise you increase the incline by 1% to make it the same "energetic cost". So a treadmill at zero incline makes it easier for you.

Many people say treadmill running is harder

If you do even the briefest of searches on the web then you will see many people report that treadmill running is harder than running outside. It's even said by people who own a treadmill so they are less likely to turn their nose up at treadmill running. While speed training is often done on a treadmill, they're not associated generally with running fast.

It's even proven by the world records. We'll take the marathon as an example and the world record outside is 2:02:57 and the world record for a treadmill marathon is 2:21:40. So while the science says it's easier, the reality from people running the distance appears to show otherwise. So we need to think about the reasons it could be harder.

6 Reasons treadmill running could be harder

1. Heat

First of all the heat, no matter what you do, running indoors always makes you feel uncomfortably hot. A fan doesn't make any difference. Outside you feel cooler even if there's little wind. Heat can slow you down in a big way. Next is that a treadmill affects your stride length, whether you're worried about falling off or you are too tall for the deck. It's something you think about.

2. Treadmill calibration

The calibration of the speed or the distance could be out. If you've had the treadmill a while or it's been used a lot the measurements may not be so accurate as they once were. It is strange because many runners must set the pace they know they can do but feel it's too much to stick with. Hence they feel like they're slower running on a treadmill.

3. Poor running form

There's no getting away from it. Running on a treadmill is like a balancing act. You could be running at some speed and you're doing it on a small deck. You may not be running as naturally as you do outside. You may have less confidence to extend yourself and you don't feel as free. All this could lead to your running form suffering. It could be a minor change but it makes a difference.

4. Variety of speed

The treadmill is very limiting when it comes to speed. Outside you can increase your speed on a whim. You don't have to press a button on a console to do it. Of course you can calculate what speed you need to go at to achieve a time for a certain distance. But the freedom just isn't there. There are no natural changes in incline on a treadmill which can affect your speed.

5. Running muscles

We use less of the muscles in our feet and legs when we run on a treadmill. Outside we can use every muscle we can to make our runs more efficient. Therefore we tend to do it slower on a treadmill. The same muscles also get overused which can have an affect on endurance running. Running outside exercises the muscles in a superior way.

6. Dislike of treadmills

There's a reason many runners call it the "Dreadmill". It's well known to be considered extremely boring compared to running outside. There's no beautiful scenery and the treadmill can be a lonely experience. I know of no running clubs for treadmill runners. I've never seen a race take place on a treadmill. The dislike is well deserved.

Final thoughts

The science says one thing and people's experience is another. I'm inclined to believe the science, I think it is easier. What if the world record holder for the outside marathon tried his running indoors. Then we could see if the marathon could be done quicker. And I think it probably could, we need more examples like this.

The thing is it's so fashionable to reject the treadmill as boring, more difficult and harder. Every other comment on a web forum mentions how boring they are and that is the reason for a slower time. This is why perhaps more research needs to be done before we can answer this very important question. Do you run slower on a treadmill than outside?

Thinking of buying a treadmill? Here's my favorite, I always recommend it when asked*

Meet The Author

Simon Gould

I'm Simon Gould. I've been around treadmills my whole life. From running on them at an early age to working in treadmill dept's of national stores. I've run outside and I've run on treadmills and I prefer running on treadmills. I still run on one nearly every day and love it.

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