The treadmill is often a necessary evil, like road running or wearing pants. Sometimes, it’s about the conditions, with ice and cold outside or darkness that makes it unsafe to run where you live (or bad air quality outdoors). I have also seen athletes rely on treadmills due to parenting duties, being on call at the hospital or just wanting to finish that show on HBO (“Barry” is that good). Whatever the reason to run inside, it doesn’t have to be a drag. Treadmill running can actually enhance training by providing an all-weather, all-situations training stimulus.
In 2017, Ryan Kaiser did almost all of his training for the Sean O’Brien 100k on the treadmill, finishing 2nd and getting a Golden Ticket to Western States.
Before the 2016 Way Too Cool 50k, my wife and co-coach Megan did her weekday running at 3 AM on a treadmill before rotations at the hospital. She went on to have one of her best races. In 2017, Ryan Kaiser did almost all of his training for the Sean O’Brien 100k on the treadmill, finishing 2nd and getting a Golden Ticket to Western States. And there are countless similar stories among all levels of athletes. So, depending on your background and goals, maybe the treadmill can be a bit less evil, and a lot more necessary.
Here are some basics of what you need to know from the research and coaching worlds to get the most out of winter treadmill training.
Grade to Simulate Level Running
A seminal 1996 study in the Journal of Sports Sciences found that at faster paces, level ground outdoor running most closely correlated to running at 1% grade on the treadmill. That study had nine trained male runners adapted to treadmill running do six minutes at varying paces on the treadmill, along with one six-minute bout outside on level ground. At 7:09 minutes per mile pace, 1% on the treadmill and flat outside were the closest analogues. At 8:03, there was no significant difference between 0 and 1%.
The takeaway is that the 1% number does not apply universally to all paces. The authors theorized that the difference could be related to some energy added by the moving treadmill belt, changes in form due to varying surface outside, air resistance or even different visual cues. At faster paces, the treadmill belt and reduced air resistance may play a bigger role. Most athletes are not going 7 minute pace or faster all the time, so it’s probably not that important what grade is used.
Taking it a step further, the exact correlation to outdoor level running is probably not key for training. Most treadmills are not perfectly calibrated (as discussed below), so worrying too much about pace is probably unnecessary. Plus, outside the lab, there are likely other variables that play a larger role than minor variations in grade, like temperature, air flow and how much egg nog you had last night. Instead, make individual decisions based on your goals, background and feel. As I tell my athletes, I care about how you feel, not what the numbers say.
The takeaway is that unless you’re doing specific pace workouts (like training for a road or track race), you don’t need to be dogmatic about the grade, and it’s probably best to mix it up a bit anyway.
Using Grade to Correlate to Speed Increases
A benefit of treadmills is that you can closely control grade and pace to get workouts that strategically target the desired goal. However, some athletes don’t love going fast on treadmills, especially lower quality machines that shake and shimmy as if they’re practicing a hot new dance craze. That’s where grade adjustments come in.
In Daniels’ Running Formula, Dr. Jack Daniels correlated different speeds and grades with oxygen uptake. The specifics of the calculation are probably not useful for most runners unless you bring a slide rule into the 24 Hour Fitness, so you can use this calculator to get a solid feel for how grade and pace are interrelated.
Don’t find yourself beholden to pace or distance numbers when your body processes that input differently than others, or differently than you might when running outside.
Say you want to do intervals around 6 minutes per mile, but don’t have the energy or machine to handle that pace. According to the calculator, you can do 7:30 per mile at 6% grade to get a similar stimulus. The theory is that power output is similar, even as pace changes. Just remember that at some point, you actually need to go fast to adapt to the unique biomechanical demands of quicker running.
Different people perceive stimuli differently. That seems like an obvious statement, but I think that all-too-often, runners judge themselves by metrics that work for others, rather than themselves. The treadmill involves different feelings of perceived exertion than outdoor running, even for athletes with similar backgrounds and fitness levels.
I cited my wife Megan’s treadmill running in the intro. Well, I am the exact opposite. I have run on the treadmill a couple times in my entire life, just to test workouts for athletes. Both times, I decided that treadmill running was im-freaking-possible and stepped off quickly after getting the data I needed. It just doesn’t work for my brain (though I imagine I’d suck it up if I lived in Barrow, Alaska).
That gets back to the general idea that perceived exertion can vary across people (or within the same person at different times). Studies show music can change how a workout feels, even changing baseline physiological responses. Visual cues or being given positive reinforcement can do the same thing. My hypothesis is that for my brain, treadmill running is the ultimate in negative reinforcement, turning what I consider a joyous act of self-expression into a numbers game. Megan might be motivated by the very thing that undermines me. It’s similar to how different athletes might run with music, while others think it’s a horrid cheapening of the sport.
There is no right answer; just be aware of how you might differ from other athletes. Don’t find yourself beholden to pace or distance numbers when your body processes that input differently than others, or differently than you might when running outside.
All of this deemphasis of numbers is especially important if the treadmill you use is not carefully calibrated. Minor variations in construction or use over time can cause the reported pace and the actual pace to vary by small margins (and sometimes, supersized margins). Since even 0.1 miles per hour can be close to 10 seconds per mile at some easy run paces, little differences can really change workout design.
Instead of worrying too much about the exact number, be attuned to feel, since the treadmill could be telling you some dirty, rotten lies, making you think you’re slower than you are. Or, it could be telling you that you are faster, in which case it’s okay to believe it.
Putting it all together, the key on the treadmill is to go by feel. Your treadmill experience may vary from someone else’s, and that’s okay.
Small increases in temperature can reduce performance substantially by lowering power output and raising perceived exertion, as outlined by a 2016 article in the Journal of Applied Physiology. That performance reduction can happen at much lower temperatures than some might think, with a 2012 PLoS One article finding marathon performance reductions as low as 50 degrees Fahrenheit. One of the same elements that may make a treadmill slightly easier than outdoor running at faster paces–lack of air resistance–can also make the treadmill harder since there is less evaporative cooling. Plus most gyms are warmer than is optimal for performance.
If you have a home treadmill, consider putting a box fan nearby. If you’re in a stuffy gym, take the temperature into account and reduce pace as needed.
Alternating Movement Patterns
Some research posits that overuse injuries may stem from repetitive motion, rather than surface hardness. If you set it and forget it with the treadmill, it can become a big old repetitive motion machine, possibly increasing injury risk. (Risk may not be uniform for all types of injuries. For example, a 2016 study found 14.2% more achilles tendon loading force on treadmills.)
I advise athletes to consider mixing it up with gradient to avoid falling into the single-motion trap. Alternating the motion may reduce injury risk (or may not). Either way, it provides you something to do while you’re staring at the wall.
Putting it all together, the key on the treadmill is to consider going by feel unless you are training at very fast paces or for very fast races when the marginal changes in grade or speed matter most. Remember that if the treadmill seems harder for you, it’s not that you are trying less hard or are less mentally tough. It’s just that the specific treadmill interacts differently with your physiology and psychology.
Perhaps best of all, consider putting a towel over the numbers on the screen, get a great playlist and use the time to escape from the pit of despair that can accompany self-judgment. It might not be the most scientific way to run, but it could be way more fun.
David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. With Megan Roche, M.D., he hosts the Some Work, All Play podcast on running (and other things), and they wrote a book called The Happy Runner.