Treadmill Running: Is It Cheating, Why Does It Feel Harder, and Should You Bother?
- 3 days ago
- 10 min read
Published August 2026
Article contains affiliate codes or links, that go to support the blog and the cancer charity work of Andy Hood
Treadmills are the absolute Marmite of the running world. Nothing divides opinion more than a post about running on a treadmill. Even the prickly subject of warm-up stretches doesn't come close.
So I'm going to weigh in. Why? Mainly because there are times when, living in the UK, we need to use one. Unless you fancy being lashed by Storm Derek and his 90mph winds and horizontal rain. Or you find yourself working away from home and the hotel gym's treadmill starts to look like the more sensible option.
Here's my short answer. Treadmills have their place, they are not cheating, and if you have never used one properly you are missing a genuinely useful training tool. But there are a few things nobody tells you, and one of them cost me three days of walking like a newborn deer.
Contents
My treadmill credentials: a 50K, a 24-hour run and over 100 miles
Fair question: who am I to weigh in on this thorny topic?
Does multiple marathons on a treadmill, a 50K ultra on a treadmill in the middle of a shopping centre, and a 24-hour non-stop treadmill run clocking up over 100 miles give me any authority?
I'm sorry, but yes. Yes it does.
Is running on a treadmill cheating?
No. And the people who say it is have usually never tried to hold marathon pace on a belt for three hours with no wind on their face.
The treadmill vs road running argument usually comes down to one claim, so let's deal with that first.
The idea that "the belt does the work" is the most repeated claim in this argument and it is the one with the least behind it. When researchers pooled 33 studies comparing treadmill and overground running, most of the measurements they looked at, including ground reaction forces, stride length and stride frequency, came out broadly comparable between the two. The belt is not pulling you along. You are still lifting your body weight, still swinging your legs, still paying the metabolic bill.
There are real differences, but they are small and mostly at the point of foot strike. Your foot lands a little flatter, your knee is slightly more bent, and your body bounces up and down a fraction less. Nothing there amounts to an easier run.
What is genuinely different is the environment, not the effort. No wind resistance. No camber. No hills unless you programme them. And no chance to ease off by two seconds a mile without noticing, which is something every runner does outdoors whether they admit it or not.
Why does running on a treadmill feel harder than running outside?
Because for a lot of runners, at a lot of paces, it genuinely is harder. Just not for the reason most people assume.
The research on this is interesting. Pool the studies together and oxygen consumption comes out similar between treadmill and outdoors at the same submaximal pace, but heart rate and perceived effort do not behave uniformly. At slower paces the treadmill tends to feel easier. At faster paces heart rate and perceived effort climb higher on the belt than they do on the road. So the "it always feels harder" complaint is not universal. It depends how quick you're going.
There are three things doing the damage.
Heat. This is the big one. Outdoors at 12kph you are generating your own breeze. Indoors you are generating nothing, and your body has nowhere to dump the heat. Studies comparing treadmill running with running on an indoor track have found higher skin temperature on the treadmill for exactly this reason. Your core temperature creeps, your heart rate follows, and the pace that felt fine on Tuesday's road run feels brutal.
Broken speed perception. Runners misjudge speed on a treadmill. In one study, runners asked to reproduce their outdoor pace on a belt all ran slower than they actually had outside. Separate work on visual speed has found that runners consistently perceive a moving scene as slower than their actual running speed, and the mismatch gets worse as the pace goes up. Without the world rushing past your eyes, your brain loses one of its main pacing cues.
Nowhere for your head to go. Outdoors your attention drifts to traffic, dogs, and the state of someone's front garden. On a treadmill there is nothing to look at, so your focus turns inwards onto your breathing, your legs and your discomfort. Sports psychologists call this associative focus, and it reliably makes efforts feel harder. It also gets worse the longer you are on there, which is a lesson I learned somewhere around hour nine.
Should you run at a 1% incline on a treadmill?
Only really if you're running fast. This is the most repeated piece of treadmill advice going, and it comes from a single study: Jones and Doust, 1996. Nine trained male runners, six-minute efforts at six different speeds, compared across treadmill gradients of 0%, 1%, 2% and 3% and against a run on a level road.
Here's the bit almost nobody quotes. At the two slowest speeds they tested, oxygen cost on the road was no different from the treadmill at either 0% or 1%. The correction only started to matter as the pace picked up, because what it is compensating for is air resistance, and at easy jogging pace there simply is not much air resistance to compensate for.
Which means most of us have it backwards. We stick 1% on for the easy Sunday plod, where it is not needed, and think nothing of it for a hard session, where it might be.
Two other things worth knowing. The rule is very often credited to the American College of Sports Medicine, and that attribution is wrong. And newer work has muddied it further: a 2024 study at ETH Zurich found that running on their treadmill already produced a higher oxygen cost than running on a track at the same speed, and that adding 1% made the gap wider rather than closing it.
The practical advice is this. Do not agonise over it. If you're doing an easy run, 0% is fine. If you want the belt to feel more like the road on a harder session, 1% is a reasonable nudge. Your perceived effort is a better guide than the number on the display, because treadmills genuinely do differ from one another.
Is treadmill running bad for your joints?
There is no good evidence that it is worse for your joints than road running, and no good evidence that it is better either.
The popular assumption is that a cushioned belt must be kinder than tarmac. The problem with that assumption is that your legs adjust. Researchers have shown that runners change the stiffness of their legs to match whatever they are running on, and they make that adjustment on the very first step onto a new surface. Land on something soft and your leg stiffens up to compensate, so the total springiness of leg plus surface stays roughly constant. The cushioning gets cancelled out by your own body.
Which is why pooled research on treadmill versus overground running finds impact forces, loading rates and shock through the shin to be broadly similar between the two. There is some evidence that a treadmill is gentler than concrete specifically, but that is a fairly low bar.
The wider question, whether running wrecks your joints at all, has a much more reassuring answer. A meta-analysis of over 114,000 people found hip and knee osteoarthritis in 3.5% of recreational runners compared with 10.2% of non-runners. What matters for your joints is your total training load and how sensibly you build it, not which surface you chose on Tuesday.
Why are you so sore after a long treadmill run?
Let me come back to that 24-hour treadmill run, because I couldn't walk properly for about three days afterwards.
What I didn't realise at the time, but very painfully realised after, is that your legs work through almost exactly the same range of motion for the entire run. There are no kerbs to hop up or down. No potholes to stride over. No subtle changes in the camber of the road that quietly adjust your form and bring different muscles, ligaments and tendons into play.
A treadmill has you almost pinned to one position. Think of the pistons in an engine going up and down. That's pretty much your legs.
So if you're heading to the gym for a long run, there is a good chance you will be sore in places you have never been sore before a day or two later. It isn't a reason to avoid the treadmill. It is a reason to build up your long treadmill runs gradually rather than jumping straight from a 5K on the belt to a two-hour effort.
Treadmill running tips that actually help
Get the cooling sorted first
Most modern treadmills have a built-in fan and mine does a decent job. For the 50K and the 24-hour effort I brought in additional floor-standing fans to keep my core temperature under control. If you are going long, do not treat this as optional. If your treadmill doesn't have a fan then consider adapting your pace to heat. It is the single biggest factor in whether the run holds together. And get used to running to RPE, it can help with treadmill efforts.
Pair your device before you start
Modern treadmills will talk to your watch, your phone, or both. Get this sorted before you press start rather than fiddling with Bluetooth at 3km. If your machine will not pair with everything you would like, it is rarely a dealbreaker, as I'll explain below.
Give the session some structure
The best defence against both boredom and the piston problem is structure. Progressive runs, tempo blocks and intervals all pass far quicker than a flat 60 minutes at one speed, and they load your legs slightly differently as the pace changes.
Build up gradually
Treat your first few treadmill long runs the way you would treat a new pair of shoes or a new surface. Your body adapts, but give it a chance to. If you're new to treadmill running, start with 20 to 30 minutes and add time before you add pace.
How to use Runna on a treadmill
My training app of choice is Runna. It rebuilt me after cancer, and again after a major operation in April. And it works on treadmills too.
Members at my gym have witnessed me doing long runs, tempo efforts and speed intervals, all perfectly synced with Runna.
Runna will connect to a lot of modern treadmills, with data flowing from the machine straight into the app, which makes managing your structured plan runs effortless.
My gym doesn't have the latest tech. The treadmills are good, and they will connect to my Apple Watch health app, but not directly to Runna. The good news is that this causes no issues at all. In treadmill mode, Runna counts you in and out of the laps on a progressive run, a mixed-paced tempo effort or a set of speed intervals. I just adjust the treadmill speed a couple of seconds before each lap starts. It works flawlessly.
If you have been putting off treadmill training because you don't know what to actually do on there, a structured plan solves that problem instantly.
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Two weeks is enough to get a proper treadmill block under your belt and see whether structured sessions change how you feel about the machine. I suspect they will.
So should you try running on a treadmill?
Yes.
Treadmills have their place and I'm not afraid to use one. It can take some getting used to, and the heat will catch you out before anything else does. But when the weather is genuinely dangerous, when you're stuck in a hotel, when you need to hit precise paces without traffic lights and dog walkers ruining your splits, or when you simply want to get the session done, the belt is a tool and not a compromise.
Get the fan on. Get a plan on your phone. Give it a proper go before you decide which side of the Marmite argument you're on.
Treadmill running FAQs
Is treadmill running easier than running outside?
At easy paces it often feels easier. At faster paces it usually feels harder, mainly because of heat build-up and the lack of airflow. Oxygen cost at a given submaximal pace comes out broadly similar in the research.
Does treadmill running count as real running?
Yes. It is the same activity, minus the wind and the weather. Most training plans, including Runna's, will happily accommodate treadmill sessions.
Do I need to set a 1% incline on the treadmill?
Not for easy running. The 1% guideline comes from a 1996 study that found it only made a meaningful difference at faster paces, and at the slowest speeds tested a flat belt matched the road just as well. Use it on harder sessions if you like, but don't lose sleep over it.
Is treadmill running better or worse for your joints?
There is no strong evidence either way. Impact levels are broadly similar to running on the road, partly because your legs automatically adjust their stiffness to whatever surface you're on. Total training load matters far more than surface choice.
Why am I so sore after a long treadmill run?
Because your legs move through almost identical range of motion for the whole run, with none of the kerbs, cambers and potholes that vary your stride outdoors. Build your treadmill long runs up gradually.
How do I stop getting so hot on a treadmill?
Use the machine's built-in fan, add a floor-standing fan if you are going long, and don't overdress. Heat is the number one reason treadmill runs fall apart.
Can you do a long run on a treadmill?
Absolutely, and people have gone a great deal further than a long run. Build the distance up gradually, sort your cooling, and give the session some structure so it doesn't become 20 miles of staring at a wall.
About the author
Andy Hood is an ultra runner, cancer survivor and the writer behind runningwestwardho.co.uk, where he covers marathon and ultra training, race guides and honest gear reviews.
He has completed multiple ultras, including a 170-mile run to Land's End, a 50K on a treadmill in a shopping centre and a 24-hour non-stop treadmill run of over 100 miles. He was diagnosed with testicular cancer in 2021 after a prompt to check himself, and now campaigns for men to do the same. He came back to running after cancer treatment and again after major surgery in April, both times with a Runna plan.
He runs in Devon, on the trails around Chamonix whenever he can get there, and yes, sometimes on a treadmill.
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