😍Treadmill or Dreadmill 😱
I'll get it out of the way right now, I kinda like the treadmill. It's a useful tool. It isn't the same as running outside and depending on perspective that is what makes it useful or a horrible abomination.
The 1% Rule
Just about every article online that compares running on a treadmill to running outside has to then layout the same old, tired position that in order for treadmill and outside to "be the same" you need to set the treadmill incline at 1%. Seriously, did the authors of the gazillion articles in the last 25 years ever read the original study?
Almost every fitness article that asserts we should all run with a 1% incline misses the main points of the 1996 study that is the source of the 1% rule.
Point #1 - The scope of the study was to compare the "energetic cost" of treadmill vs outside running.
What does "energetic cost" mean? They used gas analyzers, similar to a lab VO2Max test to discern how much oxygen was being used to generate energy. This makes perfect sense if you are trying to look for differences between how much energy is required to run inside on a treadmill vs. outside.
This is great information to have if your goals are all about trying to make sure you burn the same number of calories, from the same fuel sources, on a treadmill that you would with an outside run. For most athletes, we don't decide to use a treadmill or not because it might burn a few less/more calories in the same amount of time/distance.
Point #2 - The data from the 1996 study indicates that there is no difference in "energetic cost" at slower paces
How fast do you run?
The typical marathon finisher takes 4 to 5 hours. In other words, the typical marathon pace is between 9:09 min/mile to 11:26 min/mile (5:41 km/mile to 7:07 km/mile). The slowest pace in the study was approximately a 4 hour marathon. If you are training for a marathon, some runs would be faster than marathon pace, others similar or even slower.
From the original study:
At the two lowest velocities, VO2* during road running was not significantly different from treadmill running at 0% or 1% grade but was significantly less than 2% and 3% grade.
* VO2 is the volume of oxygen consumed to create energy with aerobic respiration
Where does your pace fall in the data below?
2.92 meter/sec = 9:11 min/mile = 5:24 min/km = road running VO2 = treadmill VO2 at 0% or 1% incline
3.33 meter/sec = 8:03 min/mile = 5:00 min/km = road running VO2 = treadmill VO2 at 0% or 1% incline
3.75 meter/sec = 7:09 min/mile = 4:27 min/km = road running VO2 = treadmill VO2 at 1% incline
4.17 meter/sec = 6:26 min/mile = 4:00 min/km = road running VO2 = treadmill VO2 at 1% or 2% incline
4.58 meter/sec = 5:51 min/mile = 3:38 min/km = road running VO2 = treadmill VO2 at 1% or 2% incline
5.00 meter/sec = 5:22 min/mile = 3:20 min/km = road running VO2 = treadmill VO2 at 1% or 2% incline
If you are running fast, and you are solely worried about how many calories you are burning then maybe you should worry about the incline. If you are running slower, then the study does not confirm that calories between a treadmill at 0% vs running outside are different. To the contrary, the study says that all 3 of the following were not statistically different:
- Road Running
- Treadmill at 0% incline
- Treadmill at 1% incline
Academic studies are hard
The research is well done, and the results are concrete. It is hard to want much more. The limitation though is that it really only tells us a particular result for a single factor under a given set of circumstances. People (and authors) have then too often tried to take that one piece of information, the energetic cost of running at different speeds/inclines to justify what they already thought.
Treadmills suck!
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Even my treadmill seems to want to get outside for a run sometimes |
At the end of the day, most people who hate running on a treadmill don't need academia to produce a study to prove it and that's OK, but I'm not sure why it sometimes seems important to prove that one run is better than another. Runs are like pizza. They are always good, even if some feel better than others.
Treadmills are great!
OK, almost nobody ever says that, but they are awfully convenient and even useful.
I love running outside, but I don't feel a need to run in slippery conditions, in the cold, on snow and ice. I don't think I get a better workout when I don't know if the next footstep is going to lead to a wipeout. It also doesn't help that a cold weather run is a near guaranteed trigger for an asthma attack for me when I return to the comfy climate controlled indoors. But honestly? Sometimes I would rather run on a treadmill even if the conditions outside are perfect!
One advantage the treadmill has is consistency and for some runs that is exactly what I need. I typically do 1 or 2 "recovery" runs a week at Couch Pace (7:53 min/mile). I like to do these runs slow enough that I'm almost always comfortable, but fast enough that I can open my hips up and stretch my legs out. The problem? I'm a dumbass. Most people would reasonably say that I do these recovery runs too fast. They are probably right, but guess what? If I didn't have a treadmill to control the pace for me I'd go even faster because, again, I'm a dumbass.
I'm also a guy that loves over analyzing data. I really like it when the data is easily comparable because it was collected under consistent circumstances. The treadmill? The room is always the same temperature, 70F. The wind? 0 mph. The rain? Always dry inside. You get the point. So, these Couch Pace runs can be really cool because I always wear a heart rate monitor and when all of the variables are climate controlled and the speed set by the push of a button it can be fascinating to see how my average HR for a Couch Pace run drops over a marathon cycle. I will frequently see 15+ bpm lower HR for a Couch Pace 5 mile run in week 16 of a marathon plan than I did for a shorter 3 mile run done at the identical pace in the identical circumstances at the beginning of the training plan. I can then look back at prior marathon plans and look to see if the HR drop was better/worse and make choices about how to do the next one different. I've never once had to worry about what the weather was like in July vs January when comparing these runs.
My advice
If you need (or want) to do some of your training on a treadmill, go for it and when it comes to incline do what feels right for you. Don't just set it to 1% because that's what the interweb says to do, unless you try it and you like the way it feels. Also, keep in mind that the incline that feels helpful to you for a slow run vs. speedwork might not be the same incline. Don't worry about "energetic cost", if you like the feel of steep slow runs and fast flat runs? Go for it. Or do the opposite. It is all OK. As long as you are moving and being mindful about how the activity (inside or outside) makes you feel then you are way more likely to have already found what is best for you.
If you are nervous that after training on a treadmill you might not be able to run as fast outside then you might be interested to know that in a study of recreational runners the subjects were able to run further/faster in a 1 hour time trial on a track than they were on a treadmill, the implication being that fitness inside translates well to running outside. I'd also like to volunteer my own experience. I've done a large portion of my training for the Boston Marathon on a treadmill every year since 2014, and while my finishing times have varied I never felt that too much treadmill running left me unprepared.
My main concern is that people are hurting their training by running at an incline that doesn't feel the same as running outside and as a consequence their biomechanics are altered in ways that might not be helpful. Specifically, running on an incline is known to shorten your stride length and increase your cadence. Is this a bad thing? There is no universal answer that is going to apply to everyone. Personally, I'm more concerned about having a running stride that feels the same between treadmill/outside than I am about making sure that the energy cost is the same, so I run at 0%. If I was smarter? I'd spend a lot more time on the treadmill running with both an incline and a decline. 🤔
Additional reading
Some ways that running on an incline changes your strideGreat theoretical analysis of the physics of treadmill running by a pro triathlete
A nice treadmill vs outside summary from one of my favorite authors
