Treadmill Conversion (Read 269 times)

I know that there has been discussion about this in the past, but in my searching I couldn't find the one thing that puzzles me -- why does the conversion differ as you get faster?

By this I mean the following:

General consensus is that you should run with a 1% incline to most closely match running outdoors.  Ok, I will buy that.  However, when I look at a conversion chart (most are very similar to this one), I see something that my feeble mind can't grasp.

What is different for paces of 5.0 to 7.8 mph that differs from 8.1 to 12 mph?

When I look at the conversion chart -- if running slower, the equivalent pace at 1% is faster.  However, once you crack that 8.1 mph threshold, the equivalent pace is slower.

So, what is the explanation.

Please limit discussion to human runners and do not include bi-pedal birds, dinosaurs or mythical beings...

Air resistance.

I thought the 1% incline was to accommodate for that?

It is. 1% is the appropriate adjustment if you're running about 8mph. But since air resistance increases exponentially as speed increases, at less than 8mph you need less than a 1% adjustment and above 8mph you need more than a 1% adjustment to have the same energy cost as running outside.

 

My strategy is to not worry about it.

+1

This is a pretty good read too.  http://www.hillrunner.com/jim2/id110.html

It is. 1% is the appropriate adjustment if you're running about 8mph. But since air resistance increases exponentially as speed increases, at less than 8mph you need less than a 1% adjustment and above 8mph you need more than a 1% adjustment to have the same energy cost as running outside.

 

My strategy is to not worry about it.

+ 2 on the "don't worry about it"

I think it's important that it's discussing energy cost as well.

-Physically, your legs are moving very close to 8.0 miles in 1 hour when running at 8.0mph on the treadmill.

-Is it true that the energy level increases when running that same distance in 1 hour when there's no wind ?

Obviously, wind resistence varies under very "normal" occurrences when running outside (change in wind speed, direction, etc).

This article was posted in the treadmill isn't real running thread by Fuzzy:

http://www.runnersworld.com/workouts/how-real-runners-train-treadmills?page=single

Researchers at the University of Brighton in the United Kingdom wondered the same thing 15 years ago, so they tested a group of trained runners on treadmills and an outdoor track, measuring their signs of exertion. "The energy cost of running outdoors is always greater than running indoors whatever the pace," says Jonathan Doust, Ph.D., one of the study's authors. "The faster you run the greater the effect."

This is most clearly seen in the tactics of races like the Tour de France, where the peloton saves energy by sharing the cost of breaking the wind. "At the slower speeds of running the effect of air resistance is much less, but still measureable," Doust says. For instance, running at a pace of 6:00/mile outdoors will add 5 percent to the total energy cost due to wind resistance. This would show up as roughly five extra beats per minute on that runner's heart rate.

The study's final verdict? At paces slower than 8 mph (7:30/mile pace), no adjustment is necessary. "The difference is so small as to be meaningless," says Doust. Between 8 mph and 11.2 mph (5:21 pace), a 1 percent treadmill grade provides the right adjustment. At higher speeds you will need at least a 2 percent grade to offset the lack of wind resistance.

Only reason that this came up is the perceived effort of a tempo/interval session that I did on the treadmill was much higher than I would have expected.  

So, the Storal of the Mory is don't over think it?

I find every treadmill different - I asked at our YMCA and they said they would not calibrate them as it is a workout no matter what speed it says.  I also find different models have some inlcine pre-built in nad others do not..

 

There are 18 TM at YMCA and I just pick one and during warm up I do some striders to get a feel of what MPH on this particular TM I need to run to hit my desire effort level.  For me it is less about pace and more about effort level.  When things slow down in February (Resolutioners leave) I will try and do my speed work on same TM each time to get a little gauge of if I am improving.

Our gym at work has 9 treadmills (8 that function). There's an unspoken war over "the one" though. Whoever gets there first in the morning grabs it. I guess we all kind of realize it's the best calibrated. Sometimes the guy who clears his throat every 14 seconds (pretty sure he has some sort of mental thing) will get there before me, and put his banana on the belt and then go do shoulder presses or whatever, like he's claiming the right to the one with his banana. It makes me mad. I haven't yet expressed this anger to him yet. But he sees me. He sees my sideward glances. He feels my steely gaze. I can always tell that dude is pissed when I show up super early and am already on the one. He always drops the weights on the shoulder press thing to make a loud clang (I think because he knows this freaks me out). Maybe it's all in my head. Maybe.

Only reason that this came up is the perceived effort of a tempo/interval session that I did on the treadmill was much higher than I would have expected.  

 

So, the Storal of the Mory is don't over think it?

Yup.  Put in the effort, despite the numbers on the display, and you will be OK.