Why Can I Run On a Treadmill But Not Outside? (5 Factors to Consider)

Today I’d like to discuss, “Why Can I Run On a Treadmill But Not Outside?”

The vast majority of us tend to find outdoor running much harder than on a treadmill.

That said, I know that there are those of you who actually find treadmill running more difficult (but that’s another article).

There are actually a multitude of reasons why you can’t seem to run outside, and these are mainly due to the environment.

So, I want to focus on each of these aspects a little closer.

Why Can I Run On a Treadmill But Not Outside?

There are various reasons why you can run on a treadmill but not outside. The most common of these is that the terrain is completely different. When you run outside you have to deal with numerous obstacles such as, avoiding potholes, ducking under branches, uneven surfaces, varying temperatures, wind resistance, moving out of the way of people or dogs, and concrete is a harder surface than a treadmill deck. Plus, you rarely run at the same pace for your entire run outdoors. All of these various distractions can play on your mind, which may also affect your breathing.

1. The Terrain is Different

Two Women Running on a Beach

The most obvious reason for your difficulty with outdoor running is that the terrain is completely different.

You wouldn’t think that treadmill and outdoor running was that dissimilar, but you have far more to contend with outside.

Firstly, pavements (sidewalks) are typically made from concrete.

This is a much harder surface to run on, which makes your landing with each step more jarring on the body and the joints.

This immediately fatigues you much quicker.

You may also have to switch to tarmac, or even grass or sand (both of which are even more difficult to run on than concrete or tarmac) during your run.

Suffice to say, there’s a lot of surface issues to deal with.

So, this is nothing like running on a smooth treadmill deck.

Let’s not forget that outdoors the surfaces may also be uneven, and you often find yourself concentrating on upcoming potholes or dips in the pavement, road, grass, etc.

Now I know many of you try to make treadmill running more similar to outdoor running by adding a 1-3% gradient.

However, the treadmill surface is still far more smooth than what you can expect outside.

2. The Temperature is Different

I would hazard a guess that you typically run outside when the weather is more favourable.

Don’t get me wrong, I know there are many people who will run outdoors all year round, irrespective of what weather conditions they are greeted with.

However, most of us prefer the drier and warmer sanctuary of indoor workouts during the winter.

Therefore, you may have spent a fair few months running on your treadmill at home.

Then again, perhaps your running has been confined to the constant temperature, whether warm or air-conditioned, of a gym environment.

Realistically, by the time you’ve taken your running outside you have to contend with heat and humidity.

A Couple Running Outdoors

Let’s not forget that you may also be affected by seasonal allergies.

So, the warmer temperatures will typically cause the body to heat up a lot quicker, and therefore you’re not running anywhere near as much or for as long as you would on a treadmill.

And if you do happen to suffer from allergies this is likely to impact on your breathing.

All of these factors make it harder for you to propel yourself forward.

Just a quick note on “propelling yourself forward”.

Basically, a treadmill is assisting your legs in moving forward.

I know it may not seem like it, but the constant motion of the treadmill is literally pulling you forward.

So, in effect, there’s less work for you to do.

When you run outside it’s all you.

You’re not getting any assistance from anywhere.

3. Watch Out For Wind Resistance

In addition to the running surface and temperature, there’s also wind resistance to deal with outside.

Okay, this may be fairly obvious if it’s blowing a 10-force gale, but often this factor goes unnoticed, but still makes a big difference.

Wind resistance is unavoidable and you will always face it when you run outdoors.

Even the slightest of winds will make running that much harder.

And of course, you don’t need any wind at all, as there is always air resistance outside.

It could be a clear summer’s day, no breeze whatsoever, but you will still face some form of air resistance as you run.

This automatically means that we have to put in that much more effort to run outside.

Something that most of us don’t do is to adjust our speed to take account of air current.

As I say, you will naturally have to make more of an effort, so by running at your “usual” speed you are likely to fatigue a lot earlier.

4. Watch Your Pace

This actually leads on quite nicely from what I’ve just mentioned.

You will need to make adjustments to your speed to deal with the various conditions.

However, when you run on a treadmill your speed is taken care of.

Most of us run at a steady, constant speed.

Plus, you know exactly how fast you’re running every single second of your workout.

But the same cannot be said when you’re outside.

Firstly, even if you’re using a tracker or an app, you don’t have the ability to stare at it every single second.

Plus, there will be times that you have to change your speed to deal with various conditions.

Furthermore, there is a tendency to run much faster when you’re outside.

In fact, most of us don’t even realise that we’re doing it.

I would actually recommend slowing down even more than you would think.

You should be able to talk in short bursts whenever you run.

You may even need to slow down to 50-60% of the effort that you’re currently using.

The aim here is to allow your body and your breathing to acclimatise to this easier pace before you build your speed back up again.

Improve Your Running Speed

5. Your Mind is More Distracted Outside

So, you can clearly see there’s a lot more going on when you run outside.

And I haven’t really mentioned that you’re having to constantly dodge people, or even getting chased by dogs.

However, when you’re running on a treadmill, you can literally zone out, even watch Netflix or be in your own little world.

When faced with all the outdoors distractions your mind is also in a constant state of motion.

In fact, your mind is probably working just as hard, if not harder, as your cardiovascular and muscular systems.

This actually puts additional stress on the body.

And probably the worst thing that happens while you’re doing all this “thinking” is that you’re not 100% concentrating on your breathing.

And this of course could lead to you feeling more puffed out or simply fatiguing much quicker.

All-in-all, the various physical, mental, and emotional distractions make running outside harder than running on a treadmill.

Final Thoughts

I hope this gives you an insight into why you can run on a treadmill but not outside.

This is mainly due to all the environmental changes.

Whether this is the running surface, temperature, or wind/air resistance.

There is also a tendency to run faster outdoors, as you have no real idea of the pace that you’re keeping.

So, we often assume that faster must be better.

Finally, this does take a toll on you mentally, which can affect your breathing, so you’re likely to fatigue much faster.

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