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910 or treadmill...to whom should I defer?

Need some help on testing on the treadmill and pacing in general. My (new) 910/footpod shows a faster pace than the treadmill...which makes sense with the incline of 2. My question is which one should I be deferring to...especially for a test and setting vdot. I could calibrate out the difference...but I'm guessing I'd have to re-calibrate once I'm outside again.

7.5 MPH is an 8 min mile...but with 2% incline it's ~7:40 NGP. 

What have others done? I know the point of the 2% is account for wind resistance...so the pace there is probably not "true". But having the workouts and tests run from the 910 is way nicer...and it's the data that goes into TP/WKO. Do most just calibrate the foot pod to the 2% incline?

Comments

  • Craig - Not sure this fully answers your question, but have you seen this:

    http://www.hillrunner.com/training/tmillchart.php

    It might help you translate TM time to 'real' time.

  • I calibrated my footpod on an outside track and just use that for treadmill speed. I use 1% grade and love the footpod data so that I can upload into TP, like yourself. It may not be 100% accurate, but it's good enough.

    I've found that I get a slightly different speed from my treadmill vs. a big gym style one when I compare speeds on my Garmin. Of course you could calibrate your home treadmill if you know the length of the mat, but to me anyway, its just not worth the effort.

    Having said that, as I get closer to IM time, I'll do all my long runs outside to make sure I feel comfortable with pacing and that I capture data that is relevant to the race.
  •  Kate - Thanks for file...I have seen that before actually...and it's funny how much it matches up to the data on the 910.

    Tom - Finding a track may be the way to go. I been indoors prior to getting the 910 and haven't had it outside. 

    At the end of the day I just want to make sure I'm being honest with myself. My TP/WKO data looks like I'm blasting the workouts since the paces on the watch are under what my vdot would call for. I have to set a pretty big target range on the Garmin so I don't get the "Slow Down" alarms 

    What is the normal protocol for the treadmill 1% or 2% - I have been told both in the past.

     

  • You don'td really need an incline. I'll stick with zero for a while and then make it one or two percent and then back to zero. For some non rational reason, I'm now at 1%.



    http://www.hillrunner.com/jim2/id110.html is a good example of the issue and the science behind it.

     

    Funny, just noticed that it's from the same site that Kate referenced.  Seems to have different outcomes.

  • IMO, the incline used depends on several factors. First, the idea is to get you running at a speed equivilent (meaning: close to, not *exact*) to your speed on a track for the same effort level/HR. Since there is some wind resistence outside, even when it is calm, the incline slows you down enough to make up for that. Second, your core temp. If there is no fan in a 70F room, then you may very well go slower on a TM at high effort levels than outdoors without all that sweat getting evaporated, and so no incline might be needed.

    Another factor which limits mhy incline is my discovery over the years: if I go above 0.5%, then I start getting stress/strain in the groin and knee on the right side. At or below 0.5%, I don[t get injury risk.

  • Hmmm...all your measures have measurement error. I have a similar issue with my two powermeters that each give me significantly different measures of power even after calibration. I handle this by keeping two sets of books: When I'm on my CT, my FTP is x watts; when I'm on my Quarq, my FTP is y watts. Sometime it gets confusing, but I'm only human.
  • Craig -

    Some good input from above... but as you might imagine, this topic has come up before. A few brief answers (that basically agree with above, but I hope add to it):

    --MOST people believe (myself included) that a small incline on the treadmill is required to make the most road-like running. Depending on you and on the treadmill, the number is usually 0.5-1.5% I usually just set it to 1% and don't worry about it.

    --NGP on real ground and on treadmill isn't the same. You shouldn't get as much "credit" for going uphill on a t-mill than on the road. Don't sweat it too hard...you can use the tables you have as a first draft guide, but realize that it's an overestimate.

    --The footpod calibration is sensitive both to your pace and to whether you are running on a treadmill vs road. If you calibrated it in the HMP-TP range on teh road, that's probably the most useful to real running, but it could be off by several percent on a treadmill.

    --Treadmill distance calibrations can be off and they are very difficult to check for obvious reasons. However, if I had to, I would trust the calibration on a well-treated treadmill more than that of a footpod that was calibrated "on land" if they were off by less than 10%.

    Matt Aaronson recently did a thread on the treadmill calibration issue. He used the same footpod on multiple treadmills to be able to sort-of-calibrate the treadmills againsteach other and found they were all pretty close over some set of different machines (closer to one another than to his road-based calibration on the footpad).

    Listen to Al about perceived effort and the like. He knows everything. :-)
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