Many people avoid treadmills because they are “bad for your knees”. Oh really? Running on a treadmill helped me recover from an injury in my past and I’ve never had an issue with it. At the same time, I’ve noticed that running on cement sidewalks felt significantly more taxing than running on asphalt. So I decided to put them to the test – Cement vs. Treadmill, in a battle of surfaces.
To test this out, I did some running on both, and of course, some research.
First, let’s go through the research. It’s easy, because there isn’t any. No research comparing a treadmill’s surface to concrete exists that I’ve been able to find (help anyone?). I found some blog posts about running on a treadmill vs. running outside, but they’re very unscientific and don’t really apply. So, it looks like we’re going to be on our own for this one.
What we can do is look at what happens on a treadmill that doesn’t happen while you’re running on a static surface – on a treadmill, the belt is moving toward you. If you are heel striking, this can have dramatic results. The belt literally moves you backwards, eliminating your need to pull your leg forward with your hamstrings and glutes. The difference can be even more pronounced if you’re running on a treadmill that does not have cushioning beneath the belt. This can leave you with underdeveloped hamstrings and muscle imbalances, leading to injury.
However, if you are forefoot striking, this effect is dramatically reduced, because you’re running with a higher cadence and because of the mechanical differences in your stride. Our takeaway? Don’t heel strike on a treadmill, or you’re asking for even more trouble than you are by running outside.
When you’re running outside, there are many surfaces to run on. Grass, dirt, mulch, gravel, sand, asphalt, and cement are some of the things that might come to your mind when thinking about it. Obviously, some of these surfaces are softer than others and put less stress on your body, regardless of form. And I’d definitely recommend running on a softer surface, if possible, regardless of form.
But we are not here to talk about grass today, we’re talking about concrete. And concrete is not a soft surface by any stretch of the imagination. One of the best arguments against barefoot running I’ve ever come across is “our ancestors didn’t run on concrete”.
Why am I focusing on concrete? Because if you live in a city, it’s hard to avoid sidewalks. And while it’s be better for your body to run on asphalt, running through traffic is more likely to injure you than any form of running. So, sometimes you’re stuck with concrete. But have no fear! If you’ll recall my previous article about the science behind forefoot striking, if you’re running on your forefoot, you’re significantly less likely to injure yourself from an overuse injury. And overuse injuries are caused by excessive stress on your body.
There are also additional benefits to running outside that you can’t get from a treadmill. Running outside provides you with constant variation in terrain, hills, obstacles, and other random unforeseen things. On a treadmill, you’ll be running the exact same speed, at the exact same incline, on the exact same surface. Initially, this seems more appealing. However, running on uneven terrain forces your body to constantly adapt to the surrounding conditions, which strengthens your muscles and improves your coordination in ways that you can’t achieve on a treadmill.
So, where are we at? We know these things:
- Common sense tells us that concrete is definitely harder than a treadmill belt, but we don’t have scientific evidence of exactly how much
- Forefoot striking puts significantly less stress on your body than heel striking
- Treadmills can cause (depending on your form) muscle imbalances, leading to injury
- Running outside, on any surface, strengthens your muscles in ways that a treadmill can’t
So the question becomes, does the difference in additional stress placed on your body by running on concrete cancel out the strength you gain from running outside, and is that overall stress less than running on a treadmill with a potential muscle imbalance?
I tested out and lived to tell you about it.
If you run in barefoot or minimalist shoes, you can feel that concrete is harder and you can feel yourself get tired more quickly. This is due to the constant adjusting your body has to do outside (remember, it’s good for you). I also had trouble maintaining my form on a treadmill, not because of the belt, but because of my depth perception. Even though I’m used to running on a treadmill (and in the past have done it quite a bit), it’s still difficult to not think you’re going to step off the front of the belt. It caused me to lean way back and threw off my form in embarrassing ways.
Knowing all this, we’re arrived at a place where we can make some recommendations.
- Despite it being a harder surface, if you are a forefoot striker, running on concrete is safer because it strengthens your body and prevents muscle imbalances.
- It’s much easier to maintain your form outside (concrete) than it is on a treadmill
- If you do run on a treadmill, don’t do it exclusively – make sure you get outside once in a while to keep your body strong.
- Don’t heel strike (OK – you caught me, I’m slipping this in. But seriously, heel striking on any surface is unsafe!)
*Note – I don’t address the psychological or mental health benefits of running outside in this article. It’s strictly about safety and injury prevention.