Pm3 Force Curve

[old] Steve G · Post by **[old] Steve G** » May 29th, 2004, 10:07 am

Interesting the thread were somebody improved their 500, by just observing the force curve display, and using the info to point in the right direction. As a D user at my local gym, what should I look for on the display, anybody have screen dumps of good and bad ?? Thanks Steve

[old] mraRower · Post by **[old] mraRower** » May 29th, 2004, 1:23 pm

I believe you want a jump at the catch, keep it flat, and than the drop off at the finish

[old] Rogus · Post by **[old] Rogus** » May 29th, 2004, 1:38 pm

What does the force curve actually measure? Is it the amount of power being applied or the speed of the flywheel? The optimum force curve would be a bit different depending on what is being measured. I heard that the ideal force curve should look like a gum drop. Before I would agree I'd need to know what is actually being measured. Does anyone know?

[old] Mike Niezgoda · Post by **[old] Mike Niezgoda** » May 29th, 2004, 8:45 pm

The PM3 is plotting the torque applied to the cog which is equal to the force applied to the handle. The calculation of the plotted torque is made up of the torque required to overcome the inertia of the flywheel plus the torque required to overcome the resistance of the fan. I don't recall seeing units on the PM3 display, but a unit of force is Newton meters (Nm) and a typical measurement of Nm for a 2:00 pace is around 9 Nm peak force and around 17 Nm peak force for a 1:40 pace. For those of us that are used to other standard measures (17.5 N = 126 kg = 277 lbs). Note that I said, "peak force." In general you want as much area under the curve as possible. Therefore, the most efficient plot is one where the shape is as rectangular as possible - gumdrop works for me. I've also referred to the shape as a left leaning haystack. To achieve a rectangular shape a strong controlled drive with the legs is required with a strong transition to the back with a strong finish with the arms. You can see another view of a rower generated force plot at <a href='http://www.ps-sport.net' target='_blank'>ErgMonitor</a>. - Mike

[old] Steve G · Post by **[old] Steve G** » May 30th, 2004, 9:28 am

Thanks for replies, just been looking at erg monitor info from Paul Smith, and have copied the following from the manual. "Use the Power Plot View and try to get a “haystack” shaped curve, the flatter the top of the haystack the more efficient your stroke is. By observing the shape of the curve and the Displayed pace, it will soon become apparent that sometimes what “feels” hard is not necessarily getting you a better pace". Mine looks similar to the link from Mikes previous post, the top does not flatten like in the picture, but curves. When it says flattens, is this a straight line at the top of the curve ? Thanks for info Steve

[old] Steve G · Post by **[old] Steve G** » May 30th, 2004, 9:37 am

Mike Apologies, I didn't realise you were involved with Paul at PS Sports !! Just had a browse around and noticed Cheers Steve

[old] Rogus · Post by **[old] Rogus** » May 30th, 2004, 5:07 pm

Mike, Thanks for the info. Do you or anybody else know if the ideal force curve on the erg would be the ideal force curve for on water rowing? Also, if you're trying to get a team to make a boat faster, wouldn't you ideally want the force curve of each rower to be identical?

[old] Mike Niezgoda · Post by **[old] Mike Niezgoda** » May 30th, 2004, 8:59 pm

Rogus, You've no doubt heard the saying that "Ergs don't float"? Boats penalize bad technique while an erg does not penalize the same things at all. You can do some pretty bad things on an erg, things that would stop a boat, and generate pretty good erg scores. That said, an ideal application of force for an on water rower would 'move' an erg pretty well. And, an efficient stroke on an erg is probably an efficient stroke on a boat as well. <a href='http://www.ps-sport.net' target='_blank'>ErgMonitor</a> gives you realtime feedback on the Erg speed calculation, so you can learn to game the C2 PMx monitors for Erg scores - or conversely learn to really apply force correctly so that you don't have to game the PMx monitor. Things that the Erg rewards (or does not penalize) that a boat does not reward: - Rushed recoveries - Excessively high stroke rates - Flailing - Slamming into the stops at the catch - Excessively long drives - Unreallistically high drag factors - Using your back to take up the chain slack at the catch There have been some experiments and data collected that gives me a pretty strong impression that the more matched the rowers in a boat for force application, the faster the boat will go. Paul Smith has done some interesting experiments based on data from <a href='http://www.ps-sport.net' target='_blank'>ErgMonitor</a>. Paul noticed that one of his rowers had a pretty similar plot to Paul's when the rower was going all out and Paul was rowing pretty easy. The two of them got in a 2x together and tried out different things. They were fastest when Paul rowed easy and his rower rowed hard - faster by a good margin than when both of them were going all out. I believe Paul is in the middle of an experiment with a college team in Washington. Paul collected data from the rowers early in the season and based on the <a href='http://www.ps-sport.net' target='_blank'>ErgMonitor</a> data put together what he thought was the best team - and held onto this information. He wanted to see what the coaches put together based on traditional methods such as seat racing and Erg scores. He would then compare the team the coaches put together to the team he put together to see if they got the same results. The second part of the experiment would be to check the <a href='http://www.ps-sport.net' target='_blank'>ErgMonitor</a> data from the team to see if their force plots became more similar after rowing together. Hopefully he'll weigh in with the results. - Mike

[old] eurofoot13 · Post by **[old] eurofoot13** » June 1st, 2004, 6:10 pm

That would be really interesting to see.... I'd like to think that they could replace seat racing.

[old] tomhz · Post by **[old] tomhz** » June 2nd, 2004, 6:38 am

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (Mike Niezgoda @ May 31 2004, 12:59 AM)</td></tr><tr><td class='quote'> Things that the Erg rewards (or does not penalize) that a boat does not reward: - Rushed recoveries - Excessively high stroke rates - Flailing - Slamming into the stops at the catch - Excessively long drives - Unreallistically high drag factors - Using your back to take up the chain slack at the catch  </td></tr></table> Mike, thanks for this explanation of differences between rowing and erging techniques. 2 questions: what is the meaning of flailing? Can you be a little more specific about your last item: "Using the back to take up the chain slack at the catch" ? Why doesn't the Erg penalize this? I am particularly interested in this error because I videoed myself on the erg and found out I use my back (opening up) too early in the stroke, compared to my legs. In my opinion this is bad in rowing and erging because you need to hold back full leg power to be able to open up in this stage of the stroke. What do you think? Tom a satisfied user of Ergmonitor

[old] Mel Harbour · Post by **[old] Mel Harbour** » June 2nd, 2004, 12:30 pm

The PM3 display shows a graph of force (y axis) against time (x axis). This has the rather significant disadvantage that as the rate rises, the graph 'squashes itself' against the left hand side. It makes it extremely difficult to use the graph to synchronise the power application of the rowers. The low resolution of the display also doesn't help matters! Force against distance is much more useful. We aim to get the rowers in sync on this display (btw we use Rowperfects). If you can match stroke length, that obviously helps as well, but we can account for some issues there by altering the gearing on the blades or setting them up in the boat so that the taller athletes row slightly within themselves. Depends on the relative sizes of the rowers. I'm a firm believer (both through practical experience and a certain amount of theory), that the optimal technique on an ergo is not the same as that in a boat (doesn't matter if the ergo is a Rowperfect or a C2). If you watch Eskild Ebbeson row on the water, he uses a different technique to that which he uses on the ergo. Mel

[old] PaulS · Post by **[old] PaulS** » June 2nd, 2004, 1:24 pm

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (Mel Harbour @ Jun 2 2004, 04:30 PM)</td></tr><tr><td class='quote'>It makes it extremely difficult to use the graph to synchronise the power application of the rowers. The low resolution of the display also doesn't help matters! Force against distance is much more useful. We aim to get the rowers in sync on this display (btw we use Rowperfects). If you can match stroke length, that obviously helps as well, but we can account for some issues there by altering the gearing on the blades or setting them up in the boat so that the taller athletes row slightly within themselves. Depends on the relative sizes of the rowers. If you watch Eskild Ebbeson row on the water, he uses a different technique to that which he uses on the ergo. Mel </td></tr></table> I'd differ on this, of course. Force Vs Length is a good first comparison, however the Force Vs Time is much more critical in matching rowers precisely (not that that guarantees anything). The time element is important to consider, because as a boat increases in speed, the rower must be able to "catch the boat" before applying force, and "Long but slow" forces, even if high, will not be utilised. I'd be willing to wager that Eskild does a number of things in an Ergo Race that he rarely (if ever) practices in training, simply to get an improved Ergo Score; it happens all the time with top level rowers. Some refuse to do the normal 'cheats' and are usually known for kicking the butts of everyone else on the water, in spite of "not so hot" Ergo scores. (Their force profiles would tell you why they are good on the water though.) Since the "Ergs Don't Float" cliche has been mentioned, I thought it might be appropriate to recognize that Pavel Shurmei just won a Gold Medal in the M4x at the World Cup. Maybe we'll see him in Athens too. - Paul Smith

[old] Mike Niezgoda · Post by **[old] Mike Niezgoda** » June 2nd, 2004, 11:19 pm

</div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td class='genmed'>QUOTE (tomhz @ Jun 2 2004, 10:38 AM)</td></tr><tr><td class='quote'> 2 questions: what is the meaning of flailing? Can you be a little more specific about your last item: "Using the back to take up the chain slack at the catch" ? Why doesn't the Erg penalize this? I am particularly interested in this error because I videoed myself on the erg and found out I use my back (opening up) too early in the stroke, compared to my legs. In my opinion this is bad in rowing and erging because you need to hold back full leg power to be able to open up in this stage of the stroke. What do you think? Tom a satisfied user of Ergmonitor </td></tr></table> Flailing to me is uncontrolled movements of the body - I've seen it mainly in the arms. In one case I was demo'ing ErgMonitor for a team and one rower had this up and down movement to his hands during the drive. The coach was watching the monitor and not the rower and asked me if was sound interference causing the gatorback force curve. I told him to look at his rower and tell me what he thought. The reply was an, "Oh, I see." Tom - you are correct. Both and erg and a boat will penalize the rower for the lost power. Opening back too early be seen in ErgMonitor.... If after the 1st third of the force curve, there is a convex dip in the curve (transition from legs to back) it can often be corrected by focusing on not opening the back up too early. - Mike

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