From my experience, you have a deep division in the running world when you mention the word “treadmill.” For some, it’s a necessary part of being able to train during winter, dark mornings, and not leaving children alone in the home. For others, they’d rather fall and break a hip on black ice than submit themselves to “lesser” training on a treadmill. For me, it’s an available tool and as a younger man, I was probably in the latter camp. However, with each passing year, I have less to prove to anyone, and would rather stay healthy than force an unnecessary training error. If you are still in the camp of “outside is the only way to train” that’s fine, this just isn’t an article for you. It doesn’t particularly matter to me if that’s your stance. I know a few people who simply just can’t do it. They get dizzy. Their balance gets wonky. It’s just not going to happen for some. If you do use a treadmill and use one regularly, then please keep reading. 



Alright, with that out of the way, let’s get to the tho pic of the day- what’s the difference between running on a treadmill and over the ground? I know it’s been debated a lot, with some conflicting results. Data says nothing, and then data says there are differences. So what is it? 



Well, from a 30,000-foot view, not much. Running is running, right? And when you look at physiological metrics, they are pretty similar. But if you have run on the treadmill, especially on an irregular basis, I bet a lot of you will say, “it sure doesn’t seem like it!” I can definitely attest to that. It feels so much harder to run slower! That’s the first thing we notice when zooming in on the data- our self-prescribed pace is lower on a treadmill than it is over the ground. As I alluded to, some of this does depend on familiarity with the treadmill. People who are not familiar or used to running on the treadmill are more nervous about footing and balance. Personally, I have a great fear of doing speed on a treadmill because I a most certain I will be flying off the back end! 



So, some of it depends more on how we react to treadmill running than the treadmill itself. Is there anything physical that is different? Yes, there are two big items we can look at. 



The first, most are familiar with and is the lack of air resistance. When you run down the road, you create your own headwind. This slows you down because you fight that resistance, but it also cools you down. On a treadmill, you are stationary, so this effect is non-existent! At east paces, this is not as big of a problem, but unfortunately, the faster you run, the bigger the advantage. How is that an advantage? What I mean by that is say your speed work is at 6 minutes per mile pace. On a treadmill, that 6 min pace you are running, might use 4% less energy to run than it would on a track. However, the advantage you might have in not fighting the air resistance may not feel like it. It’s also been shown that the faster you are running, the more likely your heart rate and perceived exertion will be higher than if doing the same pace on a road or track. So physiologically it’s easier, but it feels harder! Bummer!







To play devil’s advocate, I believe it was a piece by Daniels, that indicated that it might be a wash on adjustment. This is because of the fact that if you are on a treadmill, it’s probably a warmer room- 65-70 degrees Fahrenheit. Plus, since you aren’t moving anywhere, the humidity that surrounds you, which would normally be pushed away as you ran forward, makes the effort harder. In fact, although having more of an advantage, it has been shown that even though you may have some advantage at faster speeds, both heart rate and RPE are higher on the treadmill than over the ground (at faster speeds). In any case,