Treadmill vs. Running Outside: Which Is the Better Option?

When it comes to which is the better choice between running on treadmills vs running outside, the answer is immensely helpful: yes.

They can both be great. They can also both be really crappy.

So while there isn’t a definitive answer to which is the better option for you to consider as you train for your early triathlon careers, there are 10 considerations you should keep in mind.

These considerations will help you when you’re working out your training plan, by shooting for the optimal blend of running indoors and running outdoors.

Let’s get right into it.

The convenience of a treadmill compared to outdoor running

You’re an adult, and that comes with all the many joys of running a household, raising kids, holding down jobs, and binge-watching The Mandalorian.

So the way your training plan is structured has to be as convenient as possible for you.

Outdoor runs may be more convenient for you if you have a flexible schedule, live in a location where you have a lot of running trails or quiet roads, and don’t have inclement weather.

If this is you, then you should consider doing most of your running outdoors as you’ll need little more than some running shoes and a smile (okay you need clothes, obviously) for your workouts – as convenient as it gets!

If, however, your daily schedule will push you to train outside of daylight hours, you don’t have good running options near you or have weather challenges, then you should factor in treadmill access to ensure you can run as and when you want to.

One other factor in favor of treadmills is the ability to multi-task. If you’re studying, your work involves a lot of reading, or your job comes with hours of Zoom calls where you’re a relatively passive participant, then you can really maximize your available training time on a treadmill.

Impact on your joints

All decent-quality treadmills, and certainly the commercial models that you find at your local gym, have some degree of cushioning built into the moving belt under your feet.

This enables better shock absorption than you would experience with outdoor running on a hard surface such as asphalt or concrete, with only your running shoes sitting between the road and your tendons, ligaments, and muscles.

All of this allows for an easy way for beginners to get into running more often, and slowly build up their running volume in a sustainable way.

This only really holds if you do most of your outdoor running on very hard surfaces like concrete or asphalt, however, which is, unfortunately, the case for many of us.

If you have access to unpaved trails and can find varied terrain, then the relative advantage of treadmill running starts to reduce.

Training effectiveness

Great news – there is essentially no difference in the level of physical activity and training effectiveness with treadmills vs running in the great outdoors.

Neither of them consistently provides a better workout, burns more energy than the other, or is more efficient when it comes to calories burned, efforts to lose weight, and improvements in cardiovascular fitness.

There is one small thing you need to do to ensure this is the case when running on most treadmills, however, and that is to increase the incline to 1% for all your treadmill runs.

The reason is a simple one.

When you’re running outdoors you generate your own wind resistance simply by moving forwards, but running on a treadmill, you’re stationary and therefore don’t experience the same air resistance.

Setting the incline at 1% on the treadmill for your training runs best simulates the energy cost of overcoming this wind resistance and may even give you slightly more benefit.

​All-weather training

You’ll find that most regular runners prefer running outside if possible, particularly if they have access to a good variety of trails and routes.

But you’ll find even the most vocal of the ‘a treadmill is a glorified hamster wheel’ crowd running inside on day 3 of an atmospheric river.

To be clear though, it’s not that we expect the fact that treadmills don’t get rained on to be news to you! We’re reasonably sure you’ve worked this out already.

The real benefit comes in the predictability of running on a treadmill.

When the rest of your life is actually a hamster wheel, and you’ve finally worked out how the hell to crowbar three runs into your schedule for next week, you probably don’t have the luxury of moving things around to cater to unfavorable weather conditions.

You need to get that running session done so you can move on with your day.

This is really the biggest benefit of having easy access to treadmill running year-round – it significantly reduces the risk of you missing a workout due to factors beyond your control.

Cost of a treadmill

Unless you are lucky enough to have free access to a work or school gym, cost is the biggest drawback when considering treadmill running vs outdoor running.

Unfortunately, you’ll probably need to pay a bit more to get access to a quality gym membership with enough high-quality treadmills to handle rush hour.

Cheaper gyms tend to have a handful of treadmills of varying quality, and so you could end up standing in line for a 15-minute turn on the one operational treadmill, and burn more calories standing in line than on the actual treadmill.

First prize – if you can afford it – is a treadmill in your house.

To be honest, this is a game changer unless you live in absolutely perfect conditions for running, year-round.

Deciding to run year-round is your first decision point, and if you do, then assess whether your own treadmill will help you to make that a reality.

No matter your level of fitness and speed however, there are a few things to look out for in buying your own treadmill, particularly as costs range from a couple of hundred dollars to $12 000 plus, and you can easily overpay.

Safety

You might be thinking you will never be the type of person to fall off a treadmill, because who the heck falls off a treadmill?

But then your Airpod falls out of your ear during a tempo session and while trying to avoid stepping on it, you lose your shit completely and get shot off the back like a clown out of a circus cannon.

Speaking from experience.

Airpods aside, considering that treadmill running takes place in a very controlled environment, you are likely to be safer on a treadmill vs. running outdoors.

You are less likely to incur minor injuries like rolling an ankle or being stung by a bee, and far less likely to incur major injuries like getting hit by a car or bitten by a chihuahua with short dog syndrome.

You can avoid getting caught in bad weather, have air conditioning to avoid heat exhaustion or frostbite, can stop if you’re feeling light-headed or just plain creaky, and have easy access to a toilet whenever you need it, so can avoid “those types of accidents” too.

Variety of outdoor running

There is no right or wrong answer in most of these categories, except this one.

Unlike running on a treadmill, outdoor running wins the variety race hands down, and for many runners, this is the end of the debate given how very dull a treadmill can become if you don’t manage your entertainment options well.

Outdoor runners usually have several options for running routes, often in a relatively natural environment like a city park, and can get out and explore nature with their fellow runners.

Treadmill runners have a huge amount of variety of streaming services, TED talks, and YouTube channels, but these all start to get pretty old, particularly when the weather’s good.

Even the variety brought about by uneven terrain brings huge benefits, especially if you seek out different surfaces that allow your foot to strike slightly differently with each stride, reducing the risk of overuse injuries.

Even something as common as downhill portions on an outdoor run can’t be replicated on a treadmill, as the vast majority of treadmills don’t cater for downhill running, which is a skill new runners need to focus on.

Social Interaction

Outdoor runners have a lock on this category too, especially if you’re doing your treadmill training in the basement on your own.

There are still some treadmill pros here though.

Meeting up with some of your fellow runners definitely makes a workout go quicker, and is more likely to get you out there even when you really don’t feel like it, so as not to let your running partners down.

At the same time, given the focus these days on running slowly and running within a relatively low heart rate ceiling, you may find yourself running faster or further than you really should be on a particular workout if you’re running more established runners.

The treadmill forces pace management, as opposed to running outdoors where your ego may suggest to you that you can absolutely keep up with the faster runners in your group.

The sweet spot is to find a group of friends at a similar level to you or slightly slower.

Mental benefits

You don’t have to stop and hug the trees to get a boost from exercising and running outside. Running past and waving at them also works just fine.

Seriously though, there is scientific research to support the fact that exercising outdoors can help with cognitive function, so even if you’re not into trees, they’re into you, and you should get the treadmill as well as explore nature as often as you can.

This isn’t to say that there are no mental health benefits derived from running on a treadmill.

Because you’re exercising in such a controlled environment, there isn’t a lot to distract you from your perceived exertion, and if you’re doing tempo runs or something similarly taxing, that perceived exertion could be pretty damn high.

Mental toughness and some old-fashioned grit come into play when running on a treadmill vs outdoors, which is a good thing as you’ll be needing that skill on race day!

Triathlon-specific treadmill training

Having access to a treadmill means it’s often easier for triathletes to complete multisport workouts sustainably.

The famous brick workout, where you’re combining biking with running with very little gap between each component of the workout, is often much easier to do when you have an indoor bike trainer next to your treadmill and can practice quick transitions between the two.

Triathletes are also usually pretty time-crunched trying to fit three sports into a functional adult existence, so the convenience of a treadmill as discussed earlier in this article is hugely relevant.

Lastly, many triathlon routes will be reasonably flat (although definitely not all – sand ladder on Escape from Alcatraz, anyone?), putting triathletes at less of a disadvantage relative to new runners training for a half marathon with a lot of varying inclines and downhills.

Treadmill vs road running. Yes.

Ultimately, the best way to train is the way that works best for you.

The number one way to improve your running is by running consistently, gradually increasing intensity and duration over time.

If you prefer the convenience and control of a treadmill, then that’s great. Outdoor running has definite benefits too, however, particularly if you can feel like you’re not running in the concrete jungle.