Treadmill Tip of the Week: The 1% Incline Rule

tgftmSo. You may have heard about the 1% treadmill rule:

In order for the effort of a treadmill run to equal the effort of an outside run, you must run on the treadmill at a 1% incline.

Supposedly this rule is necessary to make up for the lack of wind resistance when running inside. When you run outside there is always some degree of wind pushing against you, causing you to work the slightest bit harder than if it weren’t there (unless it’s a windy day and then you work a lot harder when running into the wind!) So the thinking is that on the treadmill it’s exactly like running outside, except there’s no wind.

But it’s not. I’ve run a lot outside and inside. I’ve run on all kinds of different treadmills and in different gyms. Running on a treadmill is not identical to running outside, except for the wind.

I do not believe in the 1% incline rule. And here’s why:

First, I want to say that if the 1% rule works for you and feels right, than go ahead and stick with it. However, I do not think this is a “rule” in the true sense of the word. Calling this a rule says that it’s always true for everyone that a 1% incline on the treadmill is necessary for the effort it takes to run a pace on the treadmill to equal running that same pace outside. That is definitely not true. It might be true in some situations for some people, but it is most definitely not a universal truth! I picture the person who declared this a hard and fast rule as one of those people who thinks running on a treadmill isn’t “real” running (whatever that means)!

It’s time to respect the ‘mill, people!


Let’s start with the objective experts, the scientists:  namely, exercise scientists who have studied the effect of wind speeds on running effort. While I do not know who Jim2 is, his synopsis of Martin and Coe and Noakes (all highly regarded sports scientists) is great. I’ll leave it to him to lay it all out. Basically, unless you’re running really fast there is no benefit to decreases wind resistance, meaning that it’s not easier to run on a treadmill than running outside.  For most easy runs, the 1% incline likely makes it more difficult to run on the treadmill than outside. It’s a bit grayer when discussing paces between say 7:30 and 5:30/mile. However we can surmise that, the slower you are in that range, the less you have to worry about it.

Wait. What Does “Easier” Even Mean Here?

Ok. Let’s take a step back. If you are generally an outdoor runner and you hop on the ‘mill do you think to yourself, “Oooo this feels sooooo easy?” Seriously? I don’t think I have ever in all my life heard someone tell me that running on the treadmill actually feels easier than running outside. Most people get on the treadmill and feel like they’re working way too hard to be running so slow (am I right? Please feel free to tell me you disagree!)

When the scientists study the effect of wind resistance on running, they are testing things like heart rate and lactic acid clearance rates. That’s great, but those are just a small fraction of the variables that impact running effort. How about a run outside on a not windy day in 45 degrees versus stuck in a smelly humid basement gym at 68 degrees? You need a 1% incline for those conditions to equal out? What about the mental challenges of staying focused while running in place for 40 straight minutes at tempo pace? What about not being able to naturally adjust your pace and needing to meta-analyze it so your brain and fingers can set the pace? That takes a lot more energy than just pushing a button, believe me.

Lastly on this point, some workouts might max out the muscular power of your legs. So by upping the incline to get the cardiovascular effort right, you’re overtaxing your biomechanics. I definitely am the type of runner who is limited more by my biomechanics than my cardiovascular fitness, so upping the incline doesn’t help me achieve the purpose of many of my workouts. Besides it making sense here on “paper” I can actually feel this, when upping the incline 1% makes things hurt in ways they’re not supposed to, in ways they certainly don’t hurt at the same pace or faster outside. I’ve been training both outside and inside long enough to know my body and I can assure you I do not need 1% incline to get the effort right.

Why Does It Even Matter? Who Cares?

Now we’re getting to the heart of this matter.  If you have 6 at 6:30 pace on the schedule, then you want to make sure you do the work of 6 miles at 6:30 pace. There are physiological benefits you seek to gain from this workout that can only be achieved if you do it at the right effort. This is always true no matter where we run and important to know.

However, there are so many things that can effect how a pace feels to you on any given run. We already talked a little about wind speed, air temperatures and boring scenery. Sometimes we just feel off for a workout. Maybe we aren’t quite recovered from our last hard run. Maybe we aren’t recovered from some big life event. Maybe the full moon is on a Tuesday this month or we’re in a progesterone slump, or hung over or just haven’t stretched enough lately.  So many things can impact the way a run feels and there are no universal rules about that. Some of us handle the heat better than others. Some of us thrive on hills. Some of us don’t blink in the face of menstrual cramps. And hey, good for you if you’re really good at handling some level of running adversity better than others! But to say every single person must adjust their pace, etc. because of this or that variable is silly.

In fact, the self-aware runner knows the right effort level her workouts requires and know how to adjust to get it right. I have not always been good about this; lord knows I have had my share of doing almost race-effort tempos trying to hit some or another pace that I had no business hitting that day. But when it comes to my treadmill workouts, I know with 100% certainty that I do not generally need to adjust the incline to get it right.

Do you?

Running on a treadmill is harder than running outside in some ways and not in others. If you’re like me and running on the treadmill always feels more difficult than outside running, then it’s not necessary to round up when setting your pace or incline.  And no, that’s not being a wuss or cheating, that’s trusting your sense of effort.

Do you believe in the 1% rule? Have you followed it, and if so, do you think it has yielded more positive results than you would have otherwise achieved?

Salty Running boss and mother of 3 little ones with PRs of 3:10:15 (26.2), 1:25:59 (13.1) and 18:15 (5k). I love to write about running culture, mental training, and fitting in a serious running habit with the rest of a busy life.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.


  1. Thank you for this article! Because of the weather here in the Northeast this past week, I ran on the treadmill for the first time in over a year. I couldn’t believe how hard it felt! I am a relatively new runner, and had always thought treadmill running should feel easier at the same pace than outside. My run on tues. was very difficult – I felt so winded and tired running at a slower pace and shorter distance than when I am outside. I know some of it is mental, but physically I felt really bad. I’ve been very discouraged and worried that I would be taking a big step back in training this winter if I need to run on the mill regularly. Thanks for letting me know I am not the only one who feels this way.
    Do you recommend running by effort on the mill, not worrying so much about pace? And will I become a bit more acclimated to it as I continue? Thanks! And sorry for the rambling..,

    1. I do recommend running by effort on the mill. I have said in previous posts that I generally run my easy runs slower on the Tm than outside, particularly at the start. I start close to a minute/mile slower on the Tm than outside! If I don’t the run feels horrible and time passes so slow as I slog through it. Start really slow and slowly increase the pace and then I’m ok. For workouts I try to hit the prescribed paces as best I can with no incline, but often I usally err on going a few seconds slow because I’d rather get through the workout a little slow than crash and burn which just seems so much more of a possibility when doing a hard run on the mill! Great questions!

      1. Thanks! I think this and the other replies to this post will help me keep me from getting too mentally discouraged this winter as I run more on the treadmill!

  2. Thank you Salty! My running friends and I have had so many “discussions” about the 1% incline rule. It has never made sense to me, and your post nails the reasons why. My hubby is prone to calf and Achilles issues, and for him, a 1% incline for every TM run is like an express route to the injured list. Thanks for addressing this!

  3. I don’t think that outside running is harder than the treadmill, I always find the treadmill to be a slower route for me. What feels like the same effort outside is 30-60 sec faster a mile for me, no matter what the incline is. Plus inside, it’s hot! And my brain is incredibly bored so the miles tick by so slowly.

  4. I completely agree with you on this. I’ve never felt that the 1% incline was needed. I feel like I am running uphill my entire run when I have it on, I know I am not running on an incline when I run outside, at least not for my entire run.

  5. “It’s time to respect the ‘mill!” Amen to that! I’m tired of the treadmill being treated like the red-headed step child of running. I always thought the 1% incline rule was total crap (especially for regular mid-packers like me).
    90% of my marathon training is happening on the preen machine right now, and I’m learning to respect it and appreciate it. And I’m sure as heck NOT going to up that incline unless I’m doing a marathon course simulation—which I’m totally doing on my next 20 miler, BTW!

  6. I always do either 1% or 2% incline when I do the TM just for the (myth) reason you list above. Maybe that accounts for why my mileage is different on my tracker that what displays on the treadmill? That is actually counting steps instead of the speed that my TM is saying??

  7. Thanks for posting – it’s helpful to know others find running on the treadmill more challenging in many ways than running outside. I don’t run on the treadmill much, but whenever I do an easy treadmill pace is literally a full 90-120s/mile slower than my natural easy pace outdoors. This is a psychological challenge in and of itself! I always put the treadmill on 1-2% incline whenever I’m on there because, like everyone else, I’d read/heard you were supposed to – now I won’t!

  8. The only nugget I would argue with for an incline is accouting for the belt carrying your foot. Think about it. When you are running outside, the ground is fixed and you are controlling your motion and movement forward. On a treadmill, the ground is moving forward for you which can be aiding your movement by the smallest amount. I had always heard to use an inclince to offset that, the wind resistance case is new to me!

  9. I had heard about the wind resistance reason (which I thought was bunk), but I always thought that using incline on the treadmill was to help biomechanics, too. Unless I’m doing an interval workout on the track, literally none of my outdoor runs are completely flat. Even the ones that I choose a flat route for an easy run. When I’m doing an easy run on the ‘mill I still play with incline within 0-2%. I would think that leaving it set at one level for a 6 mile run would hurt no matter what, whether it be set at 1% or 0%. My leg muscles need some variation! Besides, it helps with the boredom, too – like you said in your last post.

    1. I will write more about treadmills and biomechanics in a future post. It’s very very interesting! There’s no problem with using the incline if you want to, my point in today’s post is just that you don’t HAVE to t get the right effort level in.

  10. This post helped me get through my treadmill run today. I didn’t add the 1 to 2 percent incline that I had been led to believe I needed to “equalize” the difficulty. I always thought that running on a treadmill was harder than running outside. I often wondered if it was just a mental thing. Now, given the comments of others here, I am convinced that the treadmill provides all of the physical challenge of outdoor running and then some.

  11. Thank you for addressing this! I’ve had many “discussions” with my running friends about the 1% incline debate. It’s never made sense to me, and now I have some science to back up my opinion. I’m also thrilled to see the treadmill get some respect. For those of us who have craptastic winter weather, on some days it’s the only way a run will happen. Last winter I trained almost exclusively on my TM for the Arizona RnR half marathon, and set a PR at the race. I think being able to consistently train at my goal pace helped tons. Running outside and looking at my Garmin every minute to check my pace was not as effective as trying to hold a constant pace on the treadmill.

    Thanks for the treadmill tips series. I look forward to each one.

  12. This is really interesting. No matter the technicalities of the treadmill, I always find treadmill runs SO much harder than outdoor runs simply because my mind gets so bored! I never get bored running outside but on the treadmill? It’s a killer!

  13. I train using the Maffetone method – so, HR is key for me (unless I’m in an “anaerobic” phase to bust through an aerobic plateau).

    I do tend to vary the TM incline between 0-2% per The Myth – which, by they way, I’d never seen linked to wind resistance until reading this post.

    That said, I find that I can run a faster pace on the TM than outside while maintaining the same HR (aka effort) … typically, about 1 minute faster at 1.5% incline.
    Go figure!

    1. Liz,

      The Maffetone method. Using heart rate, instead of pace, as ones guide for running workouts.

      That’s a whole concept that many runners have never heard of. How has the Maffetone method work for you?

      Using heart rate is smart when trying to determine the pace and incline to run at on a treadmill that is equivilent to running outside. The main reason why I haven’t used heart rate as my guide in my most recent training is because most training plans refer to 5K pace, 10K pace, half marathon pace and do not refer to heart rate zones.

  14. I used to train on the treadmill exclusively before I joined a team, and for awhile I was a big believer in the 1-2% incline rule. When I progressed to running outdoors I stopped being comfortable on the treadmill, and found doing a slower pace on the treadmill was really hard.
    My form got really messed up after my stress fracture and the times I’ve had to run on the treadmill the past week or so were miserable — until I switched the incline. The 1% began to feel unnatural and uncomfortable, so I switched down to no incline. BETTER! Not even easier (treadmill running is never easy for me), but just better. My form was insanely better.

  15. Thanks for this post. I’ve been running for about a year and a half… I love my TM. I love not having to think about my route, about safety, about the weather (another Northeasterner here), about emergencies at home… all of it. TM just makes it easier. (I’m super lucky to have one at home).

    As for pace and effort, I was really bummed that my pace on the TM felt so much “slower” – I just got a Nike+ foot pod, and turns out, what the TM is reading, isn’t really the pace… so what is usually an 11 or 10:30 mile outside (yeah, I’m slow) with the foot pod, is reading more like a 12 or 13 mile on the TM… I consulted with a repair guy and he said most TMs are off for pace… that you should run by effort and just go with it because the repairs are often imperfect.