Power Output Compared To 500m Splits

[old] John Rupp · Post by **[old] John Rupp** » August 17th, 2005, 2:13 pm

I just now did Pete's experiment, going to the finish position with my feet straped in on the foot plates, and then seeing how long it took for the bungee and railing to bring me back to the catch.<br /><br />Perhaps I didn't wait long enough.<br /><br />According to the clock on the wall, I sat there for 30 seconds and still nothing happened.<br /><br />I was still sitting there at the finish position.<br /><br />The railing slope and bungee are not strong enough to overcome the inertia of my body, legs being down etc. It would certainly take more force than the bungee and slope just to lift up my legs.

[old] Mel Harbour · Post by **[old] Mel Harbour** » August 18th, 2005, 4:03 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(PaulS @ Aug 17 2005, 11:41 AM)</b></div></td></tr><tr><td class='quote'>Only if you include portions of the stroke when the system is deccelerating, as being "drive". (A very strange thing to do, IMO.)<br /> </td></tr></table><br /><br />We've been through that before - even if you redefine drive and recovery to be what you want them to be, you don't come out with the ratio you claim.<br /><br /><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'>And since "racing" is about 1/1000th of the time we spend rowing/erging, I'd say that you were hedging just a bit much on that answer.<br /> </td></tr></table><br /><br />I wasn't hedging anything on that.<br /><br />As it happens, the acceleration is also not great enough for when you're rowing at lower rates as well...

[old] PaulS · Post by **[old] PaulS** » August 18th, 2005, 8:02 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(JimR @ Aug 17 2005, 09:12 AM)</b></div></td></tr><tr><td class='quote'>This isn't the first thread I have read on the topic of the "physics of rowing". Since two very learned coaches are participating in this discussion I do have a question ...<br /><br />How does understanding the rowing stroke on an erg with the precision math allows translate into an improvement in 2K performance?<br /><br />JimR <br /> </td></tr></table><br /><br />Regarding 2k Erg performance: I doubt that it helps at all, it's just fun to have the debates. <br /><br />It could help if it promoted an understanding of how to accomplish some behaviors on the recovery efficiently, but I have my doubts regarding how many even want to understand that. That said, it's also important to recognize that it is important to train efficiently so that when racing (and efficiency is not a primary thought) some of the habits stay in place under stress, to help avoid the "fly and die".<br /><br />On the water it will make a lot of difference if it ever does get understood.

[old] PaulS · Post by **[old] PaulS** » August 18th, 2005, 12:53 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(neilb @ Aug 17 2005, 10:10 AM)</b></div></td></tr><tr><td class='quote'><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(PaulS @ Aug 17 2005, 11:07 AM)</b></div></td></tr><tr><td class='quote'>Okay GW, I'll kick it off with a riddle....<br /><br />Why, in the rowing stroke, do we spend more time on the recovery than the drive?<br /><br />I'll give the answer after others offer up some ideas. <br /> </td></tr></table><br /><br />Paul,<br /><br />Fairly new to erging and even newer to rowing but I will hazard a guess (and then duck).<br /><br />The drive starts/keeps the boat moving whilst during the recovery phase drag means the boat is slowing down.<br /><br />It seems right to match the recovery to the speed the boat is moving underneath you, rather than being faster/slower and as drag means this is slower than on the drive so the recovery time is slower. <br /> </td></tr></table><br /><br />"From the mouths of babes!"<br /><br />Indeed, the system is slowing during the entire recovery, and accelerating during nearly the entire Drive (if the drive is executed well). It is desireable to have the boat travel a bit farther on the recovery than on the drive, and in fact the distance covered on the drive is nearly fixed.<br /><br />Very good!<br /><br />Holm88, <br /><br />To get to 10mps is not a bad guess, but it's more than just slowing down the recovery to let distance pass. On the water we would be looking to keep the instantaneous hull speed to a minimum fluctuation about the mean system speed. This would be accomplished by maintaining a particular (and very difficult to determine) ratio of Drive to recovery, as well as how fast the body is being "packed up" into the catch position.<br /><br />My answer: Because we need more practice on the recovery than the Drive.<br /><br />Obviously contrary to my cohorts view that the drive is far more in need of practice, however without a proper recovery a good drive is going to be nearly impossible to execute anyway. In this "chicken and egg" argument, the "recovery" comes first, it also includes the parts of the stroke referred to as the "catch" and "release", though some would like to include those in the "Drive", for reasons that I do not understand.<br /><br />The C2 is not the source of the "difference in feeling" around the catch that Mel mentions, it's the recovery technique which causes the difference. The difference will show up in comparing Force profiles on and off slides, and also in performances on and off slides. Those that are considerably faster when on slides have technical faults which not only slow them down when off slides, but would also make for non-optimal boat moving skills.<br /><br />Finally, onward goes the "perfect search for the endless stroke".

[old] ranger · Post by **[old] ranger** » August 18th, 2005, 3:59 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'>Obviously contrary to my cohorts view that the drive is far more in need of practice, however without a proper recovery a good drive is going to be nearly impossible to execute anyway. In this "chicken and egg" argument, the "recovery" comes first, it also includes the parts of the stroke referred to as the "catch" and "release", though some would like to include those in the "Drive", for reasons that I do not understand. </td></tr></table><br /><br />Sage advice.<br /><br />In training, I now row longer distances at just about _twice_ the stroking power that I used to, 14.8 SPI (e.g., 1:54 at 16 spm) as opposed to 7.4 SPI (1:54 at 32 spm). The difference is due to various factors, but one of the most important is the recovery and therefore stroke ratio. As Paul explains, the recovery sets up the energies that are applied at the catch. In rowing, nothing is more important than this "preparation." Very early on in my rowing, it repeatedly struck me that rowing is like karate (etc.). Most of the art is not in the _application_ of force, but in the _preparation_ for this application.<br /><br />Re the energies expended in the recovery, I would say that most of this is a matter of habituation. We do easily what we are used to doing. Straight-line Newtonian physics doesn't have much to do with habituation, I think. What matters in habituation is doing the same thing--a lot, over and over, ad nauseum. Then it's easy. What you do awkwardly and tensely is always "difficult" (i.e., a large expenditure of energy). <br /><br />ranger<br /><br />

[old] John Rupp · Post by **[old] John Rupp** » August 18th, 2005, 4:54 pm

Rich,<br /><br />Good for you improving your power to a 1:54 pace.<br /><br />What pace were you doing before?

[old] John Rupp · Post by **[old] John Rupp** » August 18th, 2005, 4:57 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(ranger @ Aug 18 2005, 12:59 PM)</b></div></td></tr><tr><td class='quote'>I now row longer distances at just about _twice_ the stroking power that I used to ... e.g., 1:54 <br /> </td></tr></table><br /><br />Ah twice the stroking power that you used to.<br /><br />1:54 pace is 236.2 watts<br /><br />1/2 of 236.2 is 118.1 watts... which is 2:24 pace.<br /><br />That's a nice improvement.<br /><br />I really wonder though, if you're using the same effort at 1:54 pace now, as you used before at 2:24 pace.

[old] John Rupp · Post by **[old] John Rupp** » August 18th, 2005, 5:01 pm

A good way to find out would be to row some longer distance time trials, and to see if indeed you are rowing them at twice the watts power output that you used to.<br /><br />This will be very interesting to see your results!

[old] ranger · Post by **[old] ranger** » August 18th, 2005, 5:48 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(John Rupp @ Aug 18 2005, 03:54 PM)</b></div></td></tr><tr><td class='quote'>Rich,<br /><br />Good for you improving your power to a 1:54 pace.<br /><br />What pace were you doing before? <br /> </td></tr></table><br /><br />John--<br /><br />My _stroking_ power has doubled. I haven't said or done anything yet about my overall power. <br /><br />Yes, I would need to do some trials to check how my overall power has improved. My guess is that when I get fully trained with this new technique, I will do 1:50 pace for the marathon. If so, this would be a very nice improvement in efficiency. I haven't made any improvements in CV-fitness. In fact, on this, given then I am getting older, I have undoubtedly declined. <br /><br />I think I would now race a marathon at about 22 spm and 12 SPI. That's 1:50 pace. <br /><br />My pb for the maraton is 1:54 pace.<br /><br />ranger <br />

[old] John Rupp · Post by **[old] John Rupp** » August 18th, 2005, 6:07 pm

Hi Rich,<br /><br />Well improving your stroking power from 2:24 to 1:54 pace is excellent.<br /><br />I'm interested to hear of your marathon results when you do one!

[old] PaulS · Post by **[old] PaulS** » August 18th, 2005, 7:00 pm

Since Gary doesn't like any confrontation regarding this innanity (or did I forget the 's'), I suggest you sternly disagree, and get yourself "igged" ASAP. <br /><br />But if you do choose to play "banterball" for a while, I'm inclined to believe that it will be good fun.

[old] R S T · Post by **[old] R S T** » August 18th, 2005, 7:05 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(ranger @ Aug 18 2005, 09:48 PM)</b></div></td></tr><tr><td class='quote'><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(John Rupp @ Aug 18 2005, 03:54 PM)</b></div></td></tr><tr><td class='quote'>Rich,<br /><br />Good for you improving your power to a 1:54 pace.<br /><br />What pace were you doing before? <br /> </td></tr></table><br /><br />John--<br /><br />My _stroking_ power has doubled. I haven't said or done anything yet about my overall power. <br /><br />Yes, I would need to do some trials to check how my overall power has improved. My guess is that when I get fully trained with this new technique, I will do 1:50 pace for the marathon. If so, this would be a very nice improvement in efficiency. I haven't made any improvements in CV-fitness. In fact, on this, given then I am getting older, I have undoubtedly declined. <br /><br />I think I would now race a marathon at about 22 spm and 12 SPI. That's 1:50 pace. <br /><br />My pb for the maraton is 1:54 pace.<br /><br />ranger <br /> </td></tr></table><br /><br /><br />Ranger<br /><br />Good to see you contributing to the forum after a bit of an absence - I have these images of you locking yourself away doing lots and lots of UT1 high SPI rowing of late... <br /><br />A little bit off topic/thread, but hopefully you can shed some light on your expectations on a 2k. Assuming you achieve the significant improvements on your marathon PB, what would you say is a realistic revised 2k time for you, and when do you expect to be able to achieve it? Also, would this be achieved as a lightwieght or heavyweight?<br /><br />Cheers<br />RichardT

[old] gw1 · Post by **[old] gw1** » August 19th, 2005, 10:05 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE</b></div></td></tr><tr><td class='quote'>Since Gary doesn't like any confrontation regarding this innanity (or did I forget the 's'), I suggest you sternly disagree, and get yourself "igged" ASAP. <br /><br />But if you do choose to play "banterball" for a while, I'm inclined to believe that it will be good fun. </td></tr></table><br /><br />Paul,<br /><br />My reason for using the C2 are different to most, i'm not interested in the long base CV training. All my stuff is intervals, fartlek and the occasional neg split pieces. Mostly done strapless @ 20spm. Therefore my help to others is fairly limited. <br />I much prefer spend my time on the water, than online bantering. As i think i mentioned to you before however, bantering over a few beers is a whole different thing! <br />By the way i was in your neck of the woods a couple of weeks ago, flew into Seattle and drove up to Bellingham, stayed right on the water, then took the ferry out to Orcis Is, what a great place, i'd recommend any one take a trip up there at this time of year!<br /><br />Cheers<br />GW<br />

[old] c2workout · Post by **[old] c2workout** » August 19th, 2005, 11:27 pm

Here's a rough calculation of how much energy is lost by the ergometer rower having to accelerate/decelerate their bodyweight each stroke. If the rating is R (strokes/minute), then the time t [s] for each stroke is: <br />(12.1) t = 60 / R<br /><br />Assuming the rower moves up or down the slide a distance s, at the same constant speed in the stroke as well as the recovery, and changes direction instantaneously (!) at each end, the speed v will be <br />(12.2) v = 2s/t =2sR/60<br /><br />For a rower of mass m, the Kinetic Energy associated with this motion is: <br />(12.3) U = (1/2)mv^2 = 2m(sR/60)^2<br /><br />Assuming `inelastic' ends of the stroke (i.e. no `bounce' at the catch), then the rower, mass m, must supply sufficient work to recreate the kinetic energy U each time they change direction, twice every stroke, requiring a work rate (= power) of <br />(12.4) P = 2U.(R/60) = 4m.s^2.(R/60)^3<br /><br />Trying some numbers: for m=75 kg, s=1 m, R=30 str/min, this gives <br />(12.5) P = 4 x 75 x (1)^2 x (30/60)^3 = 37.5 W<br /><br />(Note that this is the same answer as Eq. 11.4, which is in fact derived for the same conditions). So the above rower is spending 37.5 W just moving up and down the slide at rate 30 (even without holding on to the handle). <br />Note that the rate appears as a cube term: changing the rate from 30 to 36 (a factor 1.2) results in a factor (1.2)^3 = 1.7 increase in power loss. Similarly, rating 24 rather than 30 consumes (0.8)^3 = 0.5 - only about half as much power is lost. <br /><br />Also, note the appearance of the stroke-length term s^2 - taller athletes are going to suffer a lot more at higher rates than shorter athletes. <br />This was found in: Chapter 12 FAQ: The Physics of Ergometers <br />Prepared by Dr. A. Dudhia, Dept. Atmospheric Physics, Oxford University, an ARA <br /><br />Cheers<br /><br />Stephen

[old] jamesg · Post by **[old] jamesg** » August 20th, 2005, 2:50 am

When D wrote s=1m I think he was just guessing. I move my cg about 60-70cm on the erg (188 height). This means my ke losses are about 50-60% less than D's estimate.<br /><br />A more complete treatment would include the pull/recovery time ratio; but this is of interest only at low ratings, when losses are in any case insignificant. It's all work done so training anyway. <br /><br />A quick catch, so that the real pull length (chain under tension) is as near as possible the overall handle travel, is probably worth more in ensuring the work we do actually gets to the flywheel (or moves the boat). A good crew gets the blade in so fast I can't even see it happen.<br /><br />If we spend the first 30-40cm of the stroke catching up with the flywheel, because the DF is too low and the rating too high, or we are slow off the stretcher, then the power losses are a direct result of bad technique, and can be reduced.

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Power Output Compared To 500m Splits

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