Your Treadmill Pace is WRONG!

Today was unseasonably warm in Kansas (shocker), forcing me inside for my run.  Actually, it kinda was my fault. I neglected to look at the weather yesterday, and waited till 1:00pm to fit my run in today.  Probably not the best decision.

Anyway, during my 8 miler on the "dreadmill," I noticed that I felt pretty good. My main set was 5 miles at an 8:13 pace, after a 2 mile warm up.  After the fifth mile, I was still feeling pretty good.  This is something I have been noticing lately.  Since more of my runs have been on a treadmill this summer than I would like, I have become accustomed to pounding away on the machines.  Recently, I have noticed that my perceived effort is always lower on a treadmill, when compared to running outdoors.  There are some likely reasons for this, like hills, heat, wind, traffic, etc.  I still thought about this as I cooled down, and decided to check into some of my HR data from previous runs to compare the 'metabolic toll'.

I was able to find 2 runs that appeared to be fairly similar, although they were 2 different "runs".  The first run was an interval run on a treadmill that I did during the first week in August.  The second run was the tempo run I did this week.

The Interval Treadmill run was a pre-determined workout, with a specific pace.  I did the intervals at a 6:40 pace for 5x800m, with a 400m recovery between:

Average HR 157 bpm, Max HR 176 bpm, Time: 49:26

The Tempo run outdoors was also a pre-determined workout that I "adjusted." I warmed up for 3 miles, maintained a 7:45 pace for 2 miles, and cooled down the last mile.  I stopped quite a bit for stoplights, as the graph shows:

Average HR 161 bpm, Max HR 180 bpm, Time: 49:54 (moving)

From these graphs, I basically can tell that I am not replicating the "road" quite as well as I want.  I know there are TONS of differences between the two (wind, rain, cars, dogs, hills, humidity, etc.), but thought I was doing a good job replicating the conditions on a "effort" standpoint. For me, the Average and Max HR data SHOULD be higher for the interval workout, regardless of where it was taking place. Even with all the stopping in my tempo run, my HR was still higher.  

After I checked these out, I searched on Google for pacing charts for treadmills, where I uncovered this:

Courtesy of trinewbies.com

According to the graph, running speed on a treadmill doesn't translate to the correct pace outside, even when hills are taken out of the equation.  Treadmill running with no incline is actually slower than running on a flat road or track because it takes less effort without wind/air resistance. Judging from the graph, the MPH setting on a treadmill is actually about 20 seconds slower per mile, when compared with a flat road pace.  That's a huge difference!!!

I don't know if treadmills factor this in when a person selects their pace, but I'm doubting it.  It seems like a simple thing to add... One easy solution would be setting the incline of the treadmill at 1%.  This brings the difference to about 2 seconds difference per mile, which is definitely more do-able. 

This was pretty eye-opening for me.  Apparently, all of my runs on the treadmill this summer have been at a pace 20 seconds slower than I thought.  That's a little frustrating.  This is another reason why you should run outside as much as possible.... If conditions allow.  This winter (and the remaining HOT days this year) when I am forced inside, I will be doing all of my runs with some incline.  OR a GIANT fan to replicate some wind resistance... 

This should work...

Thanks for reading!