OK, so I am currently involved in a rather vigorous discussion on another forum with primarily one guy, a well-respected cycling coach. This thread is over 1000 posts now. It is somewhat wide ranging but mostly is going back and forth about the proven value of the PM as a training/racing device and the proven value of PowerCranks as a training racing device. Of course, I have used the Luttrell study as part of my argument for the PC’s. Recently as part of this debate he posted a guys thesis that looked at this question, noting that they guy showed zero statistical significance between the efficiencies of the two groups in post training testing and gave a link to the paper. But, as I read the paper I believe if supports Luttrell, rather than discredit him. The problem is the two groups started out with substantially different efficiencies and the NC group actually lost efficiency during the study while the PC group gained efficiency. They ended up close together but the improvement seen in the PC group was actually statistically significant. Here is the relevant text of the paper and the relevant figure.
There were no significant differences (i.e. p >0.5) in the variables of cycling economy and efficiency between the pre- and post-training time points for the PC group on normal cranks. However, following training there was a moderate effect size for both economy (0.93) and efficiency (0.90) in the PC group. In the NC group, economy and efficiency significantly decreased from pre- to post-testing using normal cranks, with a large effect size for economy (-1.59) and a moderate effect size for efficiency (-1.36). Furthermore, the NC group possessed significantly higher cycling economy and efficiency values than the PC group at the pre-testing time point. However, there were no differences between the PC and NC group in terms of the absolute values of these variables at the post-testing time point.This resulted in a significant interaction between the groups over time (Mean ± SD values can be seen in Figure 7).
5.2.1 Economy and Efficiency for PowerCranksTM Group on Normal Cranks vs. PowerCranksTM Group on PowerCranksTM
Subjects in the PC group cycling on normal cranks (PC on Normal Cranks) had significantly higher values of economy and efficiency at the pre-testing time point compared to when they were cycling on PowerCranks™ (PC on PowerCranks™). However, no significant differences in these variables were found between the pre- and post-testing time points in the PC group. The difference in these variables between PC on Normal Cranks and PC on PowerCranks™ remained consistent following the 5-wk training period (Mean ± SD values can be seen in Figure 7).
Note that the PC subjects tested much worse when they were test on the PC’s then when they were tested on normal cranks. But, that they were closing the gap in the 5 weeks of the study. What would be especially interesting to me would be to see where they ended up once they got to the point that they tested the same be it on normal cranks or PowerCranks. Of course, that might take 6 months to two years and I doubt we will ever see that done.
Anyhow, I throw this out for any comments by any of you who are interested in this stuff.
“But, that they were closing the gap in the 5 weeks of the study.”
I’ll have to preface my comment by saying it was difficult to understand the interpretation of the results as written or what was being compared statistically other than pre- to post- comparison within each of the 3 groups. Given that, are you suggesting in the quote above that the PC(PC) group is improving at a faster rate than the PC(NC) group over the 5 week interval because the the lines seem to be converging ever so slightly? I sure hope not. The slight convergence means nothing with all that variability. The lines could just as easily have diverged slightly. I would want to see statistical analysis of the difference in the two slopes before I would suggest there was any difference in the rate of improvement between PC(NC) and PC(PC). I can’t tell from the text or figure that was done.
I would also not speculate on what happens to these data 6 months to 2 years out based on results from a 5 week experiment.
“But, that they were closing the gap in the 5 weeks of the study.”
. . . are you suggesting in the quote above that the PC(PC) group is improving at a faster rate than the PC(NC) group over the 5 week interval because the the lines seem to be converging ever so slightly? I sure hope not. The slight convergence means nothing with all that variability. The lines could just as easily have diverged slightly. I would want to see statistical analysis of the difference in the two slopes before I would suggest there was any difference in the rate of improvement between PC(NC) and PC(PC). I can’t tell from the text or figure that was done.
I would also not speculate on what happens to these data 6 months to 2 years out based on results from a 5 week experiment.
Of course i am suggesting that because that is what I would expect to happen based upon the typical user experience. As people train with the PC’s over time normal cranks and PowerCranks begin to feel the same to them. But, it is rare that people would experience this “sameness” in only 5 weeks but the convergence one is seeing suggests it is beginning to occur. Once people get to the point where they are riding them the same then they should test the same on them and convergence would have to occur. Now, I guess convergence could occur by lowering the efficiency while riding regular cranks but the initial changes suggest that is unlikely to happen.
why do you have “can’t be a scientist because I’m a physician” at the bottom of your posts…its so annoying and insulting to real physicians.
Because Andrew Coggan said that about me once here. Take up your argument with him.
maybe its time to change it up.
Why? He said it. I think it is funny. Goes to the quality of his arguments when we are going toe to toe, which we frequently do here.
He is probably having a lot of trouble keeping himself out of this one although i suspect the naysayers will stay out of this. They seem to have more fun and are more vocal when they can throw about innuendo and self-inflated opinions and have more trouble discussing real data.
whatever.
I try not to read your advertisements anyway.
See, it makes no difference. It is there to remind me of the kinds of people I have to deal with here.
And, if you can’t laugh at yourself then you are much too serious.
“have to deal with”
Why do you “Have to sell your cranks here”…are there no flea markets or other venues where you could sell?? just set up a stand next to the guy sellilng the “healing elixir”
Since no one has managed to say anything yet regarding their own interpretation let me pose this question: What do you make of the drop in efficiency in the NC group over the 5 weeks? I thought the literature indicated that cycling efficiency was pretty much fixed in individuals. How can one explain this? One explanation might be that there was a substantial calibration problem either during the pre or post testing. The control group isn’t a very good control here it would seem. If one were to make the assumption that the control group is in error and move all the values in either the pre or post testing down or up to keep the efficiency of the NC group the same I suspect the analysis of this data would have been quite different. If one believes these numbers to be real, how does one explain the drop in efficiency in this group in the 5 weeks.
“have to deal with”
Why do you “Have to sell your cranks here”…are there no flea markets or other venues where you could sell?? just set up a stand next to the guy sellilng the “healing elixir”
Actually, I don’t have to sell them here. But, I do find it useful to discuss issues associated with them with people who are generally knowledgeable to see what people are saying. Isn’t that what forums are for? And, you, of course, are not forced to open any of these threads. I wonder why you bother, especially since I tried to put in the title that this thread was for those interested in the topic.
Of course i am suggesting that because that is what I would expect to happen based upon the typical user experience. As people train with the PC's over time normal cranks and PowerCranks begin to feel the same to them. But, it is rare that people would experience this "sameness" in only 5 weeks but the convergence one is seeing suggests it is beginning to occur. Once people get to the point where they are riding them the same then they should test the same on them and convergence would have to occur. Now, I guess convergence could occur by lowering the efficiency while riding regular cranks but the initial changes suggest that is unlikely to happen.
Maybe I should say this another way: The figure shows there is no statistically significant difference between pre- and post-study values of Economy and Efficiency in the PC groups. It doesn’t matter what the lines look like on paper – they are flat statistically. These lines could just as easily be parallel or diverge if the experiment was repeated. As for why Efficiency and Economy both decrease over 5 weeks in the NC group, I would expect an exercise physiologist who has read this paper and has remained current with the science is probably the best person to have this discussion with you.
You sir, are the original Ironman of debating. I would have said f-it and given up long ago.
Given up on what? What do you think of the study, the methods and conclusions of the author, and the fact that the control group got worse? I put this out for the opinions of those who might be knowledgeable in this area. Not necessarily a “debate” issue here as no one has put forth any real opinion yet.
You sir, are the original Ironman of debating. I would have said f-it and given up long ago.
Given up on what? What do you think of the study, the methods and conclusions of the author, and the fact that the control group got worse? I put this out for the opinions of those who might be knowledgeable in this area. Not necessarily a “debate” issue here as no one has put forth any real opinion yet.
Yes they (“The Herminator”) have. You just chose to disregard it.
My guess is most people interested in this have long since figured out that you would argue for page after page that 1+1=3. And they don’t have the time or patience anymore to try to convince you that 1+1=2.
You sir, are the original Ironman of debating. I would have said f-it and given up long ago.
Given up on what? What do you think of the study, the methods and conclusions of the author, and the fact that the control group got worse? I put this out for the opinions of those who might be knowledgeable in this area. Not necessarily a “debate” issue here as no one has put forth any real opinion yet.
Yes they (“The Herminator”) have. You just chose to disregard it.
My guess is most people interested in this have long since figured out that you would argue for page after page that 1+1=3. And they don’t have the time or patience anymore to try to convince you that 1+1=2.
Rik
Mr. Rik, the Herminator’s analysis was so meager as to hardly merit a response. According to the data of this study training with PowerCranks will make other riders less efficient and this reduction is statistically significant. I guess that would work to also to give the PC’er a racing advantage. If we can’t make ourselves faster then make the other guys slower. Whatever works, right.
There are some substantial problems with this study that I see and I asked for some comments from others as to what they think. The Herminator’s simply regurgitating that result didn’t go to the original question I was asking. Your response didn’t either. But, thanks for participating anyhow.
