Power Output Compared To 500m Splits

[old] Mel Harbour · Post by **[old] Mel Harbour** » August 17th, 2005, 7:14 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Pete Marston @ Aug 16 2005, 09:32 AM)</b></div></td></tr><tr><td class='quote'>Sorry GW, I'd forgotten I hadn't replied to you on this.<br /><br />If you go back to what I said to ajspook some days ago to try, sitting at the finish with the handle in your hands and see what happens if you take your feet off the footplates, also doing the same without the handle in your hands. Both times you slide down to the front. Did you have to expend energy doing this? No, the slide is sloped down to the front end, and the bungees want to bring the handle back too.<br /><br />If your technique is good this is what takes you back down the slide. Ok, so of course you do expend a little energy on the recovery, but I believe it is (or should be) negligible. You start off by straightening your arms - the bungees assist you in this. Then your rock forward from the hips - the bungees assist you in this. Then you allow your knees to bend, and the bungees and slope of the slide let you effortlessly return to the front of the slide ready for the next catch.<br /><br />Maths and physics can be used to show a lot of things that aren't really true in practice. Like the example someone mentioned already - how much work is done holding a heavy weight stationary? It's zero because you're not moving it anywhere, but you're still having to expend energy. <br /> </td></tr></table><br /><br />Sorry if you're about to get both barrels, Pete, but things like this really wind me up.<br /><br />Firstly about the recovery. Gravity and the bungee do not provide enough force to cause an acceleration at a fast enough rate to complete the recovery in the required time. Unsurprisingly therefore, strain gauges attached to footplates record that oarsmen pull on the footplate for most of the recovery.<br /><br />Now the second bit (and the bit that really gets to me). Maths isn't showing anything that isn't really true in the situation you describe. With respect, you just don't understand what it <i>is</i> showing. They are using the terms in a rather more precise way than you are, and are also dealing with one part of a system. In the example you quote, it is true both in theory and practise that there is no work done by you on the weight you are supporting. The problem you are encountering is because of you not understanding what they mean by the term 'work done', which despite using everyday words, is a precise mathematical term.<br /><br />In layman's terms, work is the energy transferred to a moving object by a force (for the technically minded, it is defined as the line integral of the force applied along the line the object moves in with respect to the position vector).<br /><br />You then get this muddled up with the energy your body expends to create the force, which is something different. They are both energies, but they are energy transfers occuring at different points in the system.<br /><br />Mel

[old] Pete Marston · Post by **[old] Pete Marston** » August 17th, 2005, 8:08 am

What is a fast enough rate? Gravity and the bungees will get you back down to the catch. Yes you can pull on the foot straps and assist this, but you don't have to do that.<br /><br />Ok, my wording wasn't good, saying that the physics shows something that isn't true. My point was that the wording of the physics can lead someone to a different conclusion that what is really happening in practice. Yes 'work done' is a technical term that has a meaning, but to the non-physicist you are having to work to hold a weight above you head, even though there is no 'work done' in doing so.<br /><br />Con't....

[old] Pete Marston · Post by **[old] Pete Marston** » August 17th, 2005, 8:08 am

The point I was trying to make really is that in your normal erging stroke, the amount of energy you use on the recovery is negligible compared to that used on the drive. If you use more energy and rush down the slide, this is shown on the performance monitor anyway, because for the same force applied on the drive, the power reading will be higher, as the total stroke time is less. So the extra force done on the recovery, over that shown on the PM, is still pretty much zero, imo. Row with a certain force applied each drive, and keep this the same every stroke. Try to do no work, and have a very slow recovery letting only gravity and the bungees take you back for the next catch. Say the power is 203watts (2:00 pace). Now keeping the power on the drive the same, use some energy on the recovery to assist yourself back down. What happens? The power is shown on the monitor, and the watts increases.

[old] Mel Harbour · Post by **[old] Mel Harbour** » August 17th, 2005, 8:20 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Pete Marston @ Aug 17 2005, 07:08 AM)</b></div></td></tr><tr><td class='quote'>What is a fast enough rate? Gravity and the bungees will get you back down to the catch. Yes you can pull on the foot straps and assist this, but you don't have to do that. <br /> </td></tr></table><br /><br />A fast enough rate is the optimum combination of rate/force application for the maximum speed over your race distance.<br /><br />As John's so keen on pointing out, at elite level this means rating higher than you can just using gravity/bungee.<br /><br />Mel

[old] PaulS · Post by **[old] PaulS** » August 17th, 2005, 8:52 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Mel Harbour @ Aug 17 2005, 05:20 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(Pete Marston @ Aug 17 2005, 07:08 AM)</b></div></td></tr><tr><td class='quote'>What is a fast enough rate? Gravity and the bungees will get you back down to the catch. Yes you can pull on the foot straps and assist this, but you don't have to do that. <br /> </td></tr></table><br /><br />A fast enough rate is the optimum combination of rate/force application for the maximum speed over your race distance.<br /><br />As John's so keen on pointing out, at elite level this means rating higher than you can just using gravity/bungee.<br /><br />Mel <br /> </td></tr></table><br /><br /><br />Mel citing John? Now that's something!

[old] Mel Harbour · Post by **[old] Mel Harbour** » August 17th, 2005, 9:59 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(PaulS @ Aug 17 2005, 07:52 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(Mel Harbour @ Aug 17 2005, 05:20 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(Pete Marston @ Aug 17 2005, 07:08 AM)</b></div></td></tr><tr><td class='quote'>What is a fast enough rate? Gravity and the bungees will get you back down to the catch. Yes you can pull on the foot straps and assist this, but you don't have to do that. <br /> </td></tr></table><br /><br />A fast enough rate is the optimum combination of rate/force application for the maximum speed over your race distance.<br /><br />As John's so keen on pointing out, at elite level this means rating higher than you can just using gravity/bungee.<br /><br />Mel <br /> </td></tr></table><br /><br /><br />Mel citing John? Now that's something! <br /> </td></tr></table><br /><br />Whoda thunk it?!<br /><br />The biggest difference being that both you and I know the difference between training and racing...<br />

[old] PaulS · Post by **[old] PaulS** » August 17th, 2005, 10:23 am

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Mel Harbour @ Aug 17 2005, 06:59 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, 07:52 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(Mel Harbour @ Aug 17 2005, 05:20 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(Pete Marston @ Aug 17 2005, 07:08 AM)</b></div></td></tr><tr><td class='quote'>What is a fast enough rate? Gravity and the bungees will get you back down to the catch. Yes you can pull on the foot straps and assist this, but you don't have to do that. <br /> </td></tr></table><br /><br />A fast enough rate is the optimum combination of rate/force application for the maximum speed over your race distance.<br /><br />As John's so keen on pointing out, at elite level this means rating higher than you can just using gravity/bungee.<br /><br />Mel <br /> </td></tr></table><br /><br /><br />Mel citing John? Now that's something! <br /> </td></tr></table><br /><br />Whoda thunk it?!<br /><br />The biggest difference being that both you and I know the difference between training and racing... <br /> </td></tr></table><br /><br />Well, yes, but John does not make such a distinction in his voluminous, though monotonous musings.

[old] gw1 · Post by **[old] gw1** » August 17th, 2005, 11:37 am

Guys<br /><br />Lets hold off on the JR banter, i think better understanding the recovery will help alot of people.<br /><br />I've always found that my best training and time trials are done when I feel in control of my stroke recovery. I think that the stroke recovery phase of the total stroke is just as important as the drive.<br /><br />I see many gym ergers jump out of the back of their stroke, pulling back on the foot straps, only to be in a less than optimal position (bad posture) for the next catch. <br /><br />GW

[old] PaulS · Post by **[old] PaulS** » August 17th, 2005, 12:07 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(gw1 @ Aug 17 2005, 08:37 AM)</b></div></td></tr><tr><td class='quote'>Guys<br /><br />Lets hold off on the JR banter, i think better understanding the recovery will help alot of people.<br /><br />I've always found that my best training and time trials are done when I feel in control of my stroke recovery. I think that the stroke recovery phase of the total stroke is just as important as the drive.<br /><br />I see many gym ergers jump out of the back of their stroke, pulling back on the foot straps, only to be in a less than optimal position (bad posture) for the next catch. <br /><br />GW <br /> </td></tr></table><br /><br />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.

[old] JimR · Post by **[old] JimR** » August 17th, 2005, 12:12 pm

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

[old] Mel Harbour · Post by **[old] Mel Harbour** » August 17th, 2005, 12:19 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(gw1 @ Aug 17 2005, 10:37 AM)</b></div></td></tr><tr><td class='quote'>Guys<br /><br />Lets hold off on the JR banter, i think better understanding the recovery will help alot of people.<br /><br />I've always found that my best training and time trials are done when I feel in control of my stroke recovery. I think that the stroke recovery phase of the total stroke is just as important as the drive.<br /><br />I see many gym ergers jump out of the back of their stroke, pulling back on the foot straps, only to be in a less than optimal position (bad posture) for the next catch. <br /><br />GW <br /> </td></tr></table><br /><br />Well, you have to remember I come at this very much as an on-water coach.<br /><br />Very little frustrates me as much as watching novice rowers recieve lots of coaching about how to move on the recovery when they haven't even got to the point of pulling anywhere near correctly during the drive. It's by far more important than the recovery for most people.<br /><br />The recovery is an area where the C2 creates a very different feeling to a dynamic ergo or a boat. On a C2, there is more of an impulse at the start of the recovery to get your bodyweight moving, then a substantial force on the footplate as you start to change direction at the front end. On a dynamic ergo/boat the force is more like a gradual draw of the footplate in towards your body. You have to keep drawing all the way through the recovery, albeit at a controlled rate. The important thing is that just because you're pulling on something, doesn't mean you have to pull it in quickly. If I hold onto a shopping back with a straight arm and then lift it, it's my <i>choice</i> whether I lift it quickly or slowly.<br /><br />Mel

[old] Mel Harbour · Post by **[old] Mel Harbour** » August 17th, 2005, 12:20 pm

<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'>Why, in the rowing stroke, do we spend more time on the recovery than the drive? <br /> </td></tr></table><br /><br />We don't.<br /><br />Or rather, internationals racing don't.

[old] PaulS · Post by **[old] PaulS** » August 17th, 2005, 12:41 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(Mel Harbour @ Aug 17 2005, 09:20 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'>Why, in the rowing stroke, do we spend more time on the recovery than the drive? <br /> </td></tr></table><br /><br />We don't.<br /><br />Or rather, internationals racing don't. <br /> </td></tr></table><br /><br />Only if you include portions of the stroke when the system is deccelerating, as being "drive". (A very strange thing to do, IMO.)<br /><br />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 /><br />Anyone else?

[old] neilb · Post by **[old] neilb** » August 17th, 2005, 1:10 pm

<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 /><br />

[old] holm188 · Post by **[old] holm188** » August 17th, 2005, 1:34 pm

<table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td><div class='genmed'><b>QUOTE(PaulS @ Aug 17 2005, 11:07 PM)</b></div></td></tr><tr><td class='quote'><br />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 />to be able to row at 10 mps?

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