Treadmill Running vs Outside Running: What You Need to Know

Joggers preparing to run outside an Up & Running store

In a rush? In this article, you’ll learn:

Treadmill and outdoor running use your body differently: from stride mechanics to muscle activation and energy cost, the two environments create unique demands on your body that explain why they feel so different even at the same pace.
Outdoor running builds long‑term resilience: higher impact forces strengthen bones, uneven terrain activates stabiliser muscles, and the changing environment boosts mental wellbeing and race‑day readiness.
Treadmill running offers control and consistency: reduced impact, precise pacing, safer conditions and a distraction‑free setup make it ideal for beginners, structured workouts, and injury recovery.
The best approach uses both: outdoor miles develop strength and real‑world skill, while treadmill sessions support progression and safety. Using each helps you train smarter and stay consistent.

What is the difference between treadmill and outdoor running?
Treadmill vs outdoor running: which is better?

The benefits of outdoor running
The benefits of treadmill running

Should I use a treadmill, or run outside?

If there’s one debate that can split a group of runners faster than a surprise hill in the last kilometre, it’s treadmill running versus outdoor running.

Some runners swear by the open road and wouldn’t go near a “dreadmill” whereas others can’t get enough of the predictability of the indoor setup. No wind, rain, or rogue Labradors. Just you and the belt ticking along at a steady pace.

But is one actually better than the other?

In this guide, we’ll break down the differences between treadmill running and outdoor running, look at what each option does brilliantly, and how you can use both to your advantage. Read on to learn more…

What is the difference between treadmill and outdoor running?

Let’s get it clear from the start: there isn’t a single “right” way to run. Not for beginners, not for marathoners, not for anyone. Whether you’re chasing endorphins, a finish line, or just a bit of headspace, both the treadmill and the great outdoors have something valuable to offer.

But if you’ve ever stepped off a treadmill and thought, “Why does running outside feel so different?”, you’re not imagining it.

The two environments might look similar on paper (same legs, same shoes, same playlist) but the mechanics of it tell a different story.

Your body behaves differently depending on whether the ground is moving under you or you’re moving over the ground, and those differences shape everything from muscle activation to energy cost.

At Up & Running, we see this all the time during gait analysis. The same runner can look subtly (or not so subtly) different depending on the surface they’re used to.

So let’s break down what’s really going on.

Propulsion vs belt assistance

When you run outdoors, you’re responsible for every inch of forward movement.

Your body has to generate horizontal force to push you across the ground, and that force mainly comes from the posterior chain (the glutes, hamstrings, and calves) working together to extend the hip and drive you forward.

This is often called “backside mechanics”, and it’s a huge part of efficient outdoor running.

On a treadmill, the story changes. The belt moves beneath you, effectively pulling your foot backwards. Instead of pushing the ground away, you’re keeping up with a moving surface.

You still need to produce force, but the emphasis shifts. The belt reduces the amount of horizontal propulsion required, meaning the hamstrings and glutes don’t have to work quite as hard.

This slack is taken up by the quads, who take on a slightly bigger role, and the whole movement becomes more vertical than horizontal. You’re not running forwards, you’re running upwards.

This doesn’t mean treadmill running is “easier.” It’s just different.

Some runners find the reduced posterior-chain load helpful, especially during recovery phases or when managing niggles. Others notice that when they switch back to outdoor running, their hamstrings tire more quickly because they haven’t been asked to contribute as much indoors.

If you’ve ever wondered why your legs feel different after a treadmill session, this is one of the main reasons.

Stride and gait changes

Technically speaking, treadmill and outdoor running are more similar than different, but the small differences matter.

On a treadmill, a lot of runners naturally shorten their stride. Without the visual cues of moving through space, your brain adjusts your gait to match the fixed environment.

The belt also encourages a slightly quicker turnover because it’s constantly pulling your foot backwards. This can be a helpful trick for runners who tend to overstride outdoors, but it can also mask underlying gait issues that only appear when the body has to manage real-world terrain.

Outdoors, your stride adapts to the environment. You lengthen slightly on the downhills, shorten on climbs, adjust for cambers, dodge puddles, step around pedestrians, and react to subtle changes in surface texture.

These micro-adjustments activate stabiliser muscles in the ankles, hips, and core, which don’t get the same workout on a perfectly flat treadmill deck.

There’s also a perceptual element. On a treadmill, your eyes tell you you’re stationary while your legs tell you you’re moving. It’s a little sensory mismatch that can make you feel like you’re running faster than you are.

Outdoors, the opposite often happens. Because you’re moving through space, your brain underestimates the effort, especially on flat routes with long sight lines. This is why many runners feel like they’re “working harder” outside, even when the pace is identical.

Energy expenditure

One of the most common questions we hear is whether treadmill running burns fewer calories. The short answer is usually, yes, but only slightly, and only at the same speed.

Outdoors, it’s you versus the elements. Every jog puts you against wind resistance, even on a calm day. It might not feel like much, but your body has to work harder to overcome that drag.

Studies have found that running at the same pace outdoors requires more energy than running on a treadmill, simply because the treadmill removes that environmental load.

This is where the famous “1% incline rule” comes from.

Setting the treadmill to a 1% gradient compensates for the lack of wind resistance and makes the energy cost roughly equivalent to running outside on flat ground. Indeed, a lot of treadmills have a baseline incline for this very reason.

It’s not a perfect match, nothing indoors can fully replicate the variability of outdoor running, but it’s a useful guideline, especially for runners training for road races.

The other thing to keep in mind is that treadmills can make pacing deceptively easy. When the belt dictates the speed, you’re locked into a rhythm, and can ride it all the way.

Outdoors, your body has to regulate pace based on effort, terrain, and conditions. That self-regulation is a skill in itself, and it’s one reason outdoor running feels more demanding.

Ground reaction forces and impact

Another big difference is how your body absorbs impact.

Outdoor surfaces like asphalt and concrete are stiff, which means they return more force back into your body with each foot strike. This increases the load on bones and connective tissues.

It might sound counterintuitive (after all, impact is often blamed for injuries), but it’s actually essential for building bone density and long-term resilience. Your body adapts to the forces it experiences, and outdoor running provides a stimulus that treadmills simply can’t match.

Treadmills, on the other hand, have cushioned decks that are designed to absorb shock. This dampens the peak impact forces on the joints, making treadmill running more forgiving for the knees, ankles, and hips.

It’s one of the reasons treadmills are so useful for runners returning from injury or managing flare-ups.

Neuromuscular adaptation

Finally, there’s the question of how your brain and muscles communicate.

Outdoor running requires constant neuromuscular feedback. Your eyes scan the terrain, searching for obstacles or changes. Your brain anticipates these, and your muscles adjust in real time.

This improves something called “proprioception” (your sense of where your body is in space) and strengthens the small muscles that keep you balanced and efficient.

Treadmill running removes much of this variability. The surface is predictable, the pace is fixed, and the environment doesn’t change. It can be a blessing during routine workouts, though your neuromuscular system isn’t challenged in the same way.

But hey, at least you can check your phone without the risk of falling into a puddle.

Treadmill vs outdoor running: which is better?

Trying to decide whether treadmill running or outdoor running is “better” is a bit like asking whether hills are better than flats, or long runs better than intervals. Basically, it depends entirely on what you need from your training.

Instead of treating them as rivals, it’s far more useful to understand what each one does well and how they complement each other.

This calls for a table:

Factor	Outdoor running	Treadmill running
Impact & bone strength	Higher ground reaction forces strengthen bones and connective tissues	Softer deck reduces impact, which is ideal for injury‑prone runners
Muscle activation	Greater stabiliser engagement due to uneven terrain	Less posterior‑chain demand, and more quad‑dominant
Pacing & control	Self‑regulated pacing, which is affected by weather and terrain	Precise control of speed, incline, and duration
Mental experience	Fresh air, scenery, headspace, wellbeing boost	Predictable, distraction‑free, great for focus
Race specificity	Replicates real‑world gradients, wind, and surfaces	Useful for structured sessions but can’t mimic outdoor variability
Safety & convenience	Weather, traffic, and visibility can be limiting	Safe, consistent and accessible year‑round

The benefits of outdoor running

Outdoor running is the purest form of the sport, and it brings with it a set of physical and psychological benefits that treadmills simply can’t replicate:

Builds stronger bones - outdoor surfaces return more force back into your body with every footstrike, providing the kind of controlled loading your bones need to stay strong. Over time, these higher ground‑reaction forces stimulate bone remodelling, helping you develop long‑term resilience that treadmills simply can’t replicate.
Improves stabiliser strength - the subtle changes of outdoor terrain force your body to make tiny adjustments, activating stabiliser muscles in your ankles, hips and core, strengthening the muscles that keep you balanced and efficient. This is why trail runners often have great proprioception and ankle strength as the terrain trains it for them.
Encourages a natural gait cycle - without a moving belt dictating your rhythm, your stride adapts organically to the terrain. Your hip extends more fully, your glutes engage more consistently, and your arms swing more freely. These changes help you develop a gait pattern that feels fluid and natural.
Boosts mental wellbeing - fresh air, changing scenery and the feeling of covering real distance all contribute to the psychological benefits of outdoor running. Research shows that time spent in green spaces reduces cortisol, improves mood, and increases energy. Many runners describe outdoor miles as a chance to decompress, reset and reconnect with themselves.
Builds race‑day readiness - if you’re training for an outdoor event, nothing prepares you better than running outdoors. Wind, weather, gradients, and the unpredictable behaviour of other runners all affect your performance. Outdoor training helps you develop the resilience, pacing awareness and mental toughness you’ll need when the gun goes off.

The benefits of treadmill running

For all the romance of the open road, the treadmill deserves far more credit than it gets:

Offers complete control - the treadmill removes the unpredictability of the outdoors. You can lock into a specific pace, adjust incline in tiny increments and run in a stable environment free from wind, rain, traffic or icy pavements.
Supports injury management - the cushioned deck of a treadmill absorbs more shock than outdoor surfaces, reducing the load on your knees, ankles, and hips. This makes treadmill running especially helpful for beginners or runners returning from injury. Because the belt reduces the need for horizontal propulsion, it also eases the demand on the posterior chain, which is useful when rebuilding strength.
Provides safe, consistent training - poor weather and terrain can all make outdoor running challenging or unsafe. The treadmill eliminates these barriers, giving you a reliable way to stay consistent. For runners with tight schedules, it can be the key to getting a session done.
A place to practice - the treadmill is a brilliant place to focus on cadence, posture, arm swing and foot placement without worrying about obstacles or terrain. Some runners even use mirrors or video feedback to refine their technique, something that’s impossible outdoors unless you hire someone to jog backwards holding up a mirror.
Supports mental focus and routine - when life feels chaotic, stepping onto the treadmill offers a sense of structure and control. You know exactly what you’re going to get, a steady, uninterrupted run where you can switch off mentally or zone in on your goals. For beginners especially, this consistency helps build confidence and rhythm.

Should I use a treadmill, or run outside?

The good news is that you don’t have to pick a side.

Most runners get the best results when they use both the treadmill and the outdoors strategically, depending on their goals, their body, and the season. The important thing is you’re putting one foot in front of the other.

But if you want a more concrete answer, let’s break this down into four likely scenarios:

For beginners - the treadmill is a great starting point. It helps you build confidence, rhythm, and fitness without the worry. Once you’re comfortable, add in outdoor runs to develop your running skills. If you’re unsure about footwear, your local Up & Running store can point you in the right direction.
For race training - if you’re preparing for an outdoor event, outdoor running is non‑negotiable. The treadmill still has a place, especially for controlled pace work or recovery days. Check out our race training collection to find everything you need to get started.
For injury prevention & recovery - a mix of both is ideal. The treadmill offers lower impact and predictable progression, while outdoor running strengthens bones and improves neuromuscular coordination. Switching between the two spreads the load and reduces repetitive strain. If you’re unsure how to balance things, an Up & Running specialist can help.
For mental wellbeing - some days you’ll want fresh air and headspace; other days you’ll want the calm predictability of the treadmill. There’s no right answer, just choose the option that keeps you consistent, motivated and happy.

Put your best foot forward with Up & Running

No matter what your preference is, just remember that even the worst run of your life is better than the one you missed. Whether you’re looking to get started, or on the hunt for the right pair of shoes, Up & Running is here to help.

As the UK's largest independent running specialist, we have been helping runners for over 30 years. We stock shoes and clothes from the leading fitness brands, so you’ll find everything you need right here. Check out our Shoe Finder to find your next pair of shoes.

Or if you want to speak to a member of our team in person, or get a gait analysis, find your local branch with our store locator.