# Converting times from treadmill to outdoor running?

I have found a few websites that claim the oxygen usage is countered by increasing a treadmill to a 1 degree incline, however, what I'm looking for is a way to convert treadmill running times into outdoor running times (average, of course). Hopefully a simple multiplier, but a more complex function would be fine.

Is there something like this, or is there a factor I'm forgetting which makes this impossible?

Given -

Outdoor - Completely flat, little wind, similar surface (let's say a rubber track)

Indoor - Treadmill flat, same temp as outside, mph/kph calibration is correct (this is hard to prove or disprove but if you are an experienced runner you know if it is wrong)

NOTE** Just because a treadmill is on a flat floor doesn't mean you are running on level. Also - and more common - just because a treadmill is on a LEVEL floor doesn't mean the "0" level is actually level. I have seen both inclined and declined slopes for this. I have worked out at a gym where the owner kept the desirable (good location/tv) treadmills inclined on "0" so the heavy runners wouldn't use them.

Then they are the same. I have worked with people that have had faster treadmill times and others that have had faster outdoor times. It is really in their head. Personally I have the attitude that I will do anything I am "made" to do so I think I am faster on the treadmill - yes it is in my head too. Others get sick on treadmills and need to run outside. The question is very very similar to saying do you run faster on a track or road running? People have the same variances.

The 1-2% incline comment. This comes from road racers. From the road racing/marathon community they believe setting the incline to 1-2% should mimic times they would get on average when out on the road. In theory it is probably right on average but a better tool would be going between -5 to 5% to mimic the hills you will face - I know that is only possible with very high end treadmills.

Just like the outdoor winds and hills and rough road conditions you may face you can also face indoor conditions. I have ran in small rooms where I could tell the oxygen levels had depleted during my run, I personally can't stand running in humid rooms, I run slower with a video screen in front of me... We all have our likes and dislikes. If I had my way I would be in a room at 50F with little humidity at 1 PM.

If you are really really concerned then count your strides on a treadmill for one mile/2km. Is it roughly the same outside for the same distance (and don't trust all outdoor signs that give you distance info). If your strides are the same that means that you are actually running faster on the treadmill (which is not a negative thing) and you need to push yourself outside more. If your strides are different you may need to work on lengthening your stride outside.

• The 1-2% incline is generally recognized as being the best adjustment to accommodate wind resistance (The faster you run, the more you create your own air resistance) when compared to outside running. But yes, there is negligible difference overall.
– JohnP
Jul 30, 2013 at 16:45
• It is a great question because it is almost impossible to answer. I don't know how many times a person I trained was convinced that they were faster on the treadmill, until I had them talk to (an equally paranoid) runner that thought the treadmill companies were out to get him and bring down his times. I am not saying that the treadmill vs outdoor preferences were exactly 50/50 but it was close. Jul 30, 2013 at 16:54
• And some marathoners I have worked with were savants for this stuff. They would get on a treadmill and be like this is out of level or this is off by .2 mph. And they were always right. Jul 30, 2013 at 16:56
• A good, experienced runner can almost always tell you that. One of our challenges in college was running 400m repeats (up to 16) and at the end, being able to tell the coach what your time was for each of them. Anything that was off by more than 5 seconds and you ran penalty laps.
– JohnP
Jul 30, 2013 at 17:13
• That sounds like hell. I put my 14 year old through a similar program this spring. He is up a year in school so he was having some issues competing with other boys who were done growing. After a few weeks of running the 400s he thought I was Satan. I picked the 400s to help him lengthen stride. Three months later his 400 went from 1:25 to 1:06. He is now the top 3 fastest kid on a very very good football team but he paid the price. I am not sure there is a harder run or a run that produces such good overall results. If I had him do 16 of those I would have had abuse hearings. haha Jul 30, 2013 at 17:22