Power Output Graph In Pm3

[[old] RowedandRode]

When you read the PM3 literature, you find that the screen view with the power output profile shows a nice little humped parabola. <br /><br />But when I use that function, my PM3 shows a flatter, more elongated curve, with a little slope change at the end. I've tried taking shorter strokes, longer strokes, harder strokes, lighter strokes, harder-at-the-finish, harder-at-the-catch...and it always looks that way! I can't seem to reproduce the parabola <br /><br />Is the parabolic shape supposed to represent an "ideal" stroke, or just an example of someone's output? Am I taking this too seriously? Maybe it doesn't matter and I'm sounding like an obsessive..... <br />

[[old] Lexams1]

<!--QuoteBegin-RowedandRode+Aug 12 2005, 04:09 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(RowedandRode @ Aug 12 2005, 04:09 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->When you read the PM3 literature, you find that the screen view with the power output profile shows a nice little humped parabola. <br /><br />But when I use that function, my PM3 shows a flatter, more elongated curve, with a little slope change at the end. I've tried taking shorter strokes, longer strokes, harder strokes, lighter strokes, harder-at-the-finish, harder-at-the-catch...and it always looks that way! I can't seem to reproduce the parabola <br /><br />Is the parabolic shape supposed to represent an "ideal" stroke, or just an example of someone's output? Am I taking this too seriously? Maybe it doesn't matter and I'm sounding like an obsessive..... <br /> </td></tr></table><br /><br />I was wondering ...<br />is there a link where you can see what it should look like?

[[old] NavigationHazard]

<!--QuoteBegin-Lexams1+Aug 12 2005, 04:21 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Lexams1 @ Aug 12 2005, 04:21 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin--><!--QuoteBegin-RowedandRode+Aug 12 2005, 04:09 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(RowedandRode @ Aug 12 2005, 04:09 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->When you read the PM3 literature, you find that the screen view with the power output profile shows a nice little humped parabola. <br /><br />But when I use that function, my PM3 shows a flatter, more elongated curve, with a little slope change at the end. I've tried taking shorter strokes, longer strokes, harder strokes, lighter strokes, harder-at-the-finish, harder-at-the-catch...and it always looks that way! I can't seem to reproduce the parabola <br /><br />Is the parabolic shape supposed to represent an "ideal" stroke, or just an example of someone's output? Am I taking this too seriously? Maybe it doesn't matter and I'm sounding like an obsessive..... <br /> </td></tr></table><br /><br />I was wondering ...<br />is there a link where you can see what it should look like? <br /> </td></tr></table><br /><br />See <a href='http://www.concept2.com/05/rower/servic ... g10_13.pdf' target='_blank'>How To Interpret Force Curve Data (C2)</a><br /><br />

[[old] John Rupp]

According to the pdf file:<br /><br />"If you apply good solid effort all the way through your stroke, the curve will be <b>flatter and broader</b>.<br /><br />"It is not necessarily better to reach a higher peak force. A broader curve with lower max may give you a larger area under the curve.<br /><br />"You should strive for a broad arching force curve, without any sharp peaks or wobbles."<br />

[[old] NavigationHazard]

<!--QuoteBegin-John Rupp+Aug 12 2005, 05:11 PM--><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(John Rupp @ Aug 12 2005, 05:11 PM)</b></div></td></tr><tr><td class='quote'><!--QuoteEBegin-->According to the pdf file:<br /><br />"If you apply good solid effort all the way through your stroke, the curve will be <b>flatter and broader</b>.<br /><br />"It is not necessarily better to reach a higher peak force.  A broader curve with lower max may give you a larger area under the curve.<br /><br />"You should strive for a broad arching force curve, without any sharp peaks or wobbles." <br /> </td></tr></table><br /><br />This is not necessarily true, I think, especially if you're erging with an eye towards improve your OTW stroking. The argument has to do with the comparative inefficiency of an OTW stroke at each end due to the position of the oar blade at the catch and at the finish. A slow catch and power all the way through to the finish (mesa-like force curve) may not move a boat as fast as a faster catch and drive so that peak power gets applied as the oar blade reaches a right angle to the hull (Grand Teton-shaped force curve). OTW, as I understand it much of the force applied at the end of the stroke is dissipated by the angle of the blade. <br /><br />I'm sure Paul Smith can explain it a lot better than I can, if you're not igging him that is.....

[[old] John Rupp]

Here is a diagram of stroke profile improvements on a RowPerfect over a 2 month period.<br /><br /><img src='http://www.rowperfect.com/images/japan/graph10.gif' border='0' alt='user posted image' /><br /><br />Stroke lengths were the same and compared to 100% of handle force in each instance, whereas the stroke was more broad on Oct 01 than Sep 07, and more broad on Nov than Oct 01.<br /><br />Thus the improvements were from a <b>widening</b> of the stroke profile, which occurred between the peak force at the middle of the stroke, to the finish.

[[old] John Rupp]

This is a comparison of the curves for the Olympic Dutch Holland Eight in 1993, where the RowPerfect curve and the Boat curve were close to being identical.<br /><br /><img src='http://www.rowperfect.com/images/japan/graph7.gif' border='0' alt='user posted image' />

[[old] John Rupp]

Four curves prior to winter synchonization practices.<br /><br /><img src='http://www.rowperfect.com/images/japan/graph12.gif' border='0' alt='user posted image' />

[[old] John Rupp]

Four curves after winter synchronization practices.<br /><br /><img src='http://www.rowperfect.com/images/japan/graph13.gif' border='0' alt='user posted image' />

[[old] John Rupp]

In each case, the stroke profile improvements were concurrent with <b>decreases</b> in the output of peak power.

[[old] NavigationHazard]

I'm going on vacation and not going to get in an argument with you. I will content myself by noting that the physics involved in rowing are very complicated. Even the experts argue all the time about what's going on, and what's optimum and what's not. You've misunderstood my quibble with C2. I'm not advocating jumping the catch. <br /><br />On the business of timing peak force to match oar alignment, as Stephens notes, the oar travels in an arc and force applied while it's at either end of the arc is partially dissipated. He recommends optimizing the force curve so that it corresponds to a blade angle relative to the boat of 70 to 110 degrees: <a href='http://home.hia.no/~stephens/ppstroke.htm' target='_blank'>Physics And Physiology Of Rowing Faster: The Stroke.</a> Atkinson has developed the practical implications of this in his Rowing model and concluded that maximum force ought to be applied when the blade is at 90 degrees: <a href='http://www.atkinsopht.com/row/forcpeak.htm' target='_blank'>Peak Force Management.</a> You don't need to be a rocket scientist to realize that this makes intuitive sense.<br /><br />The gumdrop-shaped force curves you've cut and pasted in your posts may well represent optimum force management for OTW rowers. But my point is that on an erg, where you don't have a changing blade angle complicating the application of force via the oar, the theoretically perfect force curve would look something like this:<br /> ________<br />|######|<br />|######|<br /><br />That is, instantaneous catch, even application of power through the stroke, and instantaneous disengagement at the finish.<br /><br />In the real world an optimum force curve for erging might well look like this:*<br />______________<br /> /##########\<br />/###########\ <br /><br />That is, less like a gumdrop than a mesa.<br /><br />* Excuse the crummy ASCII art.<br /><br />OTW this kind of force curve is inefficient for the reasons noted above. <br /><br />C2 does indeed recommend striving for "gumdrop" curves on the erg, presumably as a compromise with OTW rowing. But in the next breath they talk about making them "flatter and broader" along with "broad and arching." And if the arch of the gumdrop is too broad and flattened, I don't think your stroke will move a boat very well. <br /><br />Note that C2 alludes to the complexities of rowing styles by advising OTW rowers to "ask [your coach] what he or she thinks your curve should look like."

[[old] John Rupp]

The RowPerfect curves were developed from World and Olympic Champion class rowers.<br /><br />Even so, it looks to me that what Concept2 and Stephens are saying is exactly the same as the RowPerfect graphs.<br /><br />No one said that peak force is not at a 90 percent angle, or near to the center of the drive, though it looks slightly in front of that.<br /><br />The point is that having a broad and flatter arched profile, that has more area under the curve -- especially from the area of peak force to the finish -- is more important than having a higher peak force.