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The 1% Incline Treadmill Myth - Part 2

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A forumite took issue with my original post on this subject. The following are my comments to him.


> All of that and in the end you state:


> My recommendation is to ignore any advice that says

> that it is necessary to always use a 1-2% incline

> adjustment to compensate for the lack of wind

> resistance. Instead, use the combination of speed

> control and incline adjustment that best makes a

> treadmill run "feel like" it is giving you the

> training benefit that you desire.


> So then the 1 to 2% guideline is quite appropriate is

> it not?


Since it is often difficult to interpret emotion within the written word, I’m unsure if your comment is dripping with sarcasm or intended to be tongue-in-cheek. :-) With your permission, I will assume that you have a sense of humor and intend the latter. :-)


Seriously. No, I do not think the 1-2% guideline is "quite appropriate". It is appropriate at times for some runners. But, a blanket 1-2% guideline for everyone to specifically compensate for the lack of air resistance misleads many runners in many situations and can actually make treadmill running more difficult than over-ground running. It is a "sound bite" response to questions that people post on these forums in a serious attempt to understand treadmill running vs. outdoor running. And it is a response that addresses only one of several factors that should be considered....and it’s one that is relatively minor, to the point of being insignificant for most runners. I think those who are seeking thoughtful guidance to serious questions deserve more than that.


> If you and arepper take issue with the study I used

> for having a small sample size then I assume you take

> that same tact with McMiken and Daniels sinc this

> study had one FEWER subjects than the Jones and Doust

> study I used.


I don't "take issue" with the study. As far as I know, it was conducted carefully and in compliance with good scientific practices. I simply observed that, as arepper noted, it did have a small sample size comprised of highly trained runners, which may or may not be representative of a broad spectrum of runners of all levels of ability. And, although I did not know it, I am not at all surprised that the McMiken and Daniels study utilized about the same sample size. I suspect that all such studies are directed to the high performance end of the running spectrum and use similarly small sample bases. I doubt if any researcher has the resources, especially time and money, to spend on large samples of a broader spectrum of runners.


All of the studies we, collectively, have mentioned arrived at a similar basic conclusion....all other parameters being equal, running at speeds below a certain threshold and at 0% incline is equivalent to running outdoors and the lack of air resistance is insignificant, whereas above that threshold an incline adjustment is needed to make the two running conditions equivalent at the same pace. What differed between the studies was the level of that threshold....5:22, 6:00 or 8:03 min/mile. That is what interested me and I speculated about it. You clarified one of the potential reasons that I had suggested (sample size) so as to indicate that it probably isn't a factor. At least not for those two studies, which arrived at significantly different thresholds....6:00 vs. 8:03....although there still could be other differences between their specific sample bases.


Actually, the extract that you cited from the McMiken and Daniels' report of their study indicates that the submaximal portion of their study only extended to a 6:00 pace and they found that "neither VO2 max nor aerobic requirements of running were significantly different in track and treadmill determinations". So, they didn't really arrive at a "threshold" point. If they had continued submaximal tests to faster paces, they might have confirmed Davies' conclusion that the threshold is at a pace of 5:22.


In any event, the thresholds demonstrated by all of the studies occur at speeds which are faster than the typical training paces of most runners, thus indicating that there is no significant difference between running on a treadmill at 0% incline and outdoors in calm air for most runners. In my opinion, this indicates that it makes no sense to tell the majority of runners that they should compensate for something that doesn't really affect them.


> I would also note that these studies were done almost

> 20 years apart.  It is possible the technology

> advanced to make more valid measurements with less

> error.


I seriously doubt that the availability of more modern equipment and technology makes the recent study more accurate or valid than the earlier ones. The conclusions of all of these studies reflect relative data, not absolute measurements. Any inaccuracies resulting from equipment and/or techniques should affect both treadmill and track measurements equally in each study. Such measurement inaccuracies should cancel and not affect the final conclusions, regardless of the technological era in which the studies were conducted. I suspect the benefit of newer technology is to make the control and analysis processes easier, not to increase their accuracy. ”....but then again, what do I know?", since I am not an expert in this area. ;-)


> Treadmill calibration is certainly an issue, but it

> is a red herring in this case and only clouds the

> issue in a theoretical discussion.


I agree that treadmill calibration would cloud the issue in a theoretical discussion concerning the effect of air resistance, per se. That’s why I didn’t mention it in that part of my post. I only raised the point at the end of the post when pointing out that air resistance pales in comparison to other factors, such as treadmill calibration, in the broader subject of comparing treadmill and over-ground running....which is what people come to the forum to seek information. In that context, the air resistance issue is the red herring because it is irrelevant for most runners.


> If the treadmill

> calibration is off (and the likelihood is pretty good

> if using a health club treadmill from my experience)

> then it is all moot as you are not going to be sure

> that is going on.


Precisely the point! I could not agree more! A miscalibrated treadmill, which is common, as you said, can make all other factors, such as lack of air resistance, moot....even for the minority of runners who are fast enough to be noticeably affected by the lack of air resistance.



> Lastly, I would not use the testing protocol to

> support your notion in that the incline on the

> treadmill is done at the end of the test for a few

> possible reasons one of which is safety.  In Dave's

> LEAP lab, when the treadmill is going at sub 5 min

> pace at it would be at the end of a VO2max test the

> potential for someone losing balance is pretty high

> (actually had a to catch a kid on a treadmill one

> time when he stumbled running at 4:30 ish pace).  In

> these cases, increasing the grade is a means to

> safely increase the intensity to "max out".


I think I understand your point. It’s a good one. Perhaps safety is one reason Martin and Coe reduced the pace from 5:00 to 6:00 min/mile for the last few minutes of their test protocol when they cranked up the incline to max out a runner’s VO2.


The bottom line to all of this is that I think that, regardless of what the studies indicate, focusing on compensating for lack of air resistance is taking a component (micro) view of a subject that really begs for a system (macro) view. And it isn’t even one of the more significant components. Even worse, depending on the other components, introducing an automatic adjustment for it can often actually produce inequality between treadmill and over-ground running.