Running on a Treadmill vs. Outdoors

All runners want to know: running on a treadmill or running outdoors, which is better? The answer, like all ‘big’ questions in life, is it depends.

"Both treadmill and outdoor running have their benefits, and the choice between the two largely depends on individual preferences,” says David Jou, DPT (Physical Therapist).

That said, this guide will dig into the pros and cons for both running outdoors and hitting the treadmill. So, you can choose how to train.

Key takeaways at a glance:

• The treadmill is great for training in a controlled environment. You set the incline, the speed, the distance

• But the treadmill doesn’t train as many muscles as stepping out the front door

• Running outdoors engages more muscles and gives you the chance to prepare for races in real-world conditions

• But running on hard ground or technical terrain can be unforgiving on the joints

Treadmill Running: The Pros

Let’s start off with the benefits of treadmill running. 

The Controlled Environment 

‘Pro’ number one for treadmills – they let you control your entire setup. You pick a pace, incline, interval pattern, and decide how long you spend working out. The machine does the rest, tracking your distance, calories, heart rate, and more.

Any super specific goal, the controlled environment of the treadmill wins out. If you’re pushing for a time goal, such as the six minute mile, the treadmill is a great testing ground. See how it feels to run at that pace, and drop it down if you need to.

You can also relax, knowing you won’t encounter any surprises. Wild animals, downpours, searing heat, running out of water, or getting lost: none of it can touch you on the treadmill. Instead, gear up for a safe gym space with unlimited water refills.

Injury Prevention 

Treadmills are designed to go easier on joints, especially compared to running outdoors on tough concrete or uneven terrain like trails.

Most treadmills have shock absorption systems built into the deck, which reduce the impact forces that your joints (especially knees, ankles, and hips) would absorb during each stride. They supply a flat, consistent surface, meaning your body doesn't have to compensate for cracks, rocks, slopes, or other outdoor hurdles. This helps prevent injuries. Plus it’s great for runners still bouncing back from injury.

Top Tip: Complement your treadmill workouts with strength training, stretching, and proper recovery time to further prevent injury.

Treadmill Running: The Cons

But what about a sense of adventure? The thrill of the trail? Here’s the downside of treadmill running.

Lack of Real-World Simulation

For many, the treadmill can feel ‘boring’ or ‘monotonous’. There’s a lack of new scenery, as you don’t really run anywhere or move location. For this reason, the treadmill isn’t ideal for distance running.

You’re also not learning how to respond to obstacles (curbs, wind, slopes, corners, etc.) on the treadmill. So, if prepping up for an outdoor race, you still need some training en plein air (outdoor). This will help you skill up on scanning and planning ahead in the real-world.

Less Muscle Engagement

With no changes in terrain, elevation, or direction, treadmill running simply doesn’t activate all the muscles that outdoor jogs do. When out running on uneven ground, there’s the added challenge of stabilizing your stride, which conditions the ankles, hips, and core. 

Owing to this, while the treadmill can help injury recovery and prevention, anyone over-relying on it can end up getting injured.

“If you're only running inside, certain muscles could become weak and de-conditioned, which sets you up for injury when you do get back to running outside,” says Rondel King, Certified Strength and Conditioning Specialist & Exercise Physiologist.

If you’re not paying attention, it’s easy to fall into poor running form. There’s also no wind indoors, so you’re getting a slightly easier run.

Top Tip: Use 1–1.5% incline on the treadmill to mimic outdoor effort.

Outdoor Running: The Pros

Let’s delve into the benefits of outdoor running.

Exploration: The World is Your Gym

Ahh, the great outdoors. Running in the fresh air is brilliant for stress reduction and improved mood. If you head out in daylight, the Vitamin D boost doesn’t hurt either.

Take on a real mountain adventure — the time running will pass in no time. Looking to go off-road and afar? We recommend these top 10 European trails, while closer to home there are bucket list US routes all over the country.

Alternatively, running outdoors with friends is a great way to stay social. Why not join an outdoor running group?

Fuller Muscle Engagement

Outdoors, you propel yourself entirely, which requires more effort from your glutes and hamstrings. Meanwhile, turns and curves in real-world routes engage the lateral muscle more vs. the treadmill. The constantly varying elevation outside even activates the quads, calves and glutes differently.

"You get more muscle activation outside, because your feet have to grab the ground to propel you,” Rondel King explains. “A treadmill does some of that work for you by feeding the belt to you."

Don’t forget, treadmills don’t let you practice downhill running. So, it’s best to run some outdoor hills near you to supplement your treadmill workouts.

Outdoor Running: The Cons

Why running outdoors isn’t simply a walk (or run) in the park. 

It’s Out of Your Hands

While the controlled environment of the treadmill helps runners train for specific goals, that’s not always possible outdoors. You plan a speed run and the path freezes over, so you’re forced to tread carefully. Then it starts raining halfway through... You get the picture. Life happens. It’s the joy and the peril of running in the open.

Speaking of perils, it can sometimes be dangerous to run outdoors. Oncoming traffic needs watching out for when crossing roads, while bears, insects, and other wildlife can pose a threat out on the trail.

Top Tip: It’s always a good idea to plan ahead and let someone know where you’re running.

Quality, protective clothing for all weathers also readies you for off-grid adventures.

Complications & Data Tracking

We’ve all forgotten to press ‘start’ on a fitness tracker. And let’s be honest — how accurate are they, really? One of the perks of treadmill running is that it automatically tracks your key metrics, like distance and time, without needing extra devices — or worrying whether they’re charged.

If you're aiming to complete a specific workout, like set intervals, you’ll need to plan how you’ll prompt yourself to change pace and time your recovery periods. Outdoors, you might even need to scout out the right hills to match your workout goals.

Which is Better for Specific Goals? Treadmill vs. Outdoor Running Comparison

Depending on your goal, here’s the training method that’s typically best:

Conclusion: The Ultimate Approach is the Best of Both Worlds

There’s no need to rely on one way of training:

• Complete a mix of outdoor and treadmill runs weekly

• Switch up the inclines you tackle and consider intervals to constantly challenge your body

• Remember to strength-train the glutes, hamstrings, and core

• Try other sports (such as soccer, swimming, and cycling) to vary your workouts and unleash new fitness benefits, such as endurance 

FAQs: Running Outdoors vs. Treadmill Running

Still deciding between the treadmill and the trail? Find the answers to frequently asked questions here…

• Is running on a treadmill bad for you? Not generally. For many runners, it can be a safe and effective way to train, especially with a specific goal in mind. But relying on the treadmill too much can limit you.

• Is it okay to run a treadmill every day? Yes, as long as you’re listening to your body and varying your training. You should never run in pain, and you should allow enough time for your body to recover between exercises.

• Why is it not recommended to run on a treadmill? There are some limitations and drawbacks to treadmill running. For example, the lack of varied terrain means your stabilizer muscles don’t get worked the same way they do during outdoor runs. Some runners also tend to shorten their stride or change their posture on a treadmill, which can lead to poor running form over time.

• Is it healthier to run outside or on a treadmill? Both outdoor and treadmill running come with great health benefits. But getting outside offers time in fresh air and nature, which is proven to boost mood. Soaking up sunlight also helps boost vitamin D production, which supports immune function and bone health.

• Is it better for beginners to run outside or on a treadmill? To build basic fitness safely, a treadmill is a great entry point. But if you enjoy being outside and your goal is to run in the open, there’s no ‘minimum fitness requirement’ or barrier to getting started. Lace up, and head out the door. Here’s a beginner’s guide to running 5k.

• Will I burn as many calories on a treadmill as I will outside? Both modes of running can burn similar calories, if the intensity and duration are the same. To make the treadmill more of a calorie burner, bump up the incline and keep your form in tact.