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Leg drive

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12 years 2 weeks ago - 12 years 2 weeks ago #11823 by Kocho
Replied by Kocho on topic Re: Leg drive
Greg S., I read through some of the web site (did not see any illustrations or videos, just text). On first reading, I'm confused by his writings somewhat... Partly, because of his somewhat convoluted language, partly because I think his explanations make sense to me at one level but don't quite make sense on another.

Specifically about the lean of the boat towards the blade in the water during the power phase. If this is what he is saying, then I have the following thoughts, only related to the "wall of water" part of the explanation and ignoring other possible aspects.

- The pull on the blade on the right side translates into forces that propell the kayak forward and turn it left. No question there. Not much to discuss, at least for now.

- Edging the kayak to the right (towards the blade in the water) alters the in-water hull profile. So that if we were going straight but not paddling (just gliding) the kayak will eventually turn left. That part (edging right) does not make sense to me - why would one want to do that? The paddle is already trying to make the kayak turn left so by leaning left we accentuate that tendency even further. It would make more sense to edge away from the paddle so that the edging conteracts the turning forces.

Look at this video: the kayaker edges away from the paddle:



.



To understand the turning forces and the concept of "wall of water" I think one needs to look at the shape of the hull under water and how it interacts with the water dynamically.
- The pivot point (for the rotational forces due to the paddle) is near the paddler/center of the boat.
- But because the boat is moving, the actual pivot point around which the boat turns is further forward (the faster the boat moves, the further forward that pivot point moves). This is why the rear of the boats usually sway left to right (especially well seen on the Hiki that Szolt is paddling).
- To lock the stern, one uses the rudder or the shape of the hull or both. In a ski, the rear is pretty lose by design, so the ski can zigzag using the rudder. So, edging a ski towards the paddle will not lock it agains water. And if anything, it might further release the stern as the rudder will tend to be at a climbing angle being pushed sideways...
- The bow of the kayak has nearly vertical sides on the racing kayaks and is very well planted. I do not see an immediate benefit of edging as far as the bow is concerned, because the pivot point is so far forward that side to side most motion occurs at the stern, not the bow.

So, what do you say? Despite what that paper says, it seems to me edging is not needed due to any "wall of water" dynamics. It won't hurt much to edge either, whether done towards or away from the paddle... And the only reason one might be edging is that it somehow allows them better ergonomics during the stroke - and that apparently seems to be very personal, with some top athletes edging towards and other away from the paddle...
Last edit: 12 years 2 weeks ago by Kocho.

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12 years 2 weeks ago - 12 years 2 weeks ago #11824 by gstamer
Replied by gstamer on topic Re: Leg drive

Kocho wrote: So, what do you say? Despite what that paper says, it seems to me edging is not needed due to any "wall of water" dynamics. It won't hurt much to edge either, whether done towards or away from the paddle... And the only reason one might be edging is that it somehow allows them better ergonomics during the stroke - and that apparently seems to be very personal, with some top athletes edging towards and other away from the paddle...


First off, while I teach sea kayaking, I’m not a K1 coach. I'm not "married" to any of these concepts.

My understanding is that the lean is to exploit technique to create a more powerful stroke, such as pushing with the heel on the side of the stroke, while allowing your torso to swing slightly away from the paddle (pendulum style, while it rotates). A good video and explanation of the "torso swing" is at web.me.com/m_g_robinson/SprintStuff/page2/page2.html .

Note that Kemecsey is not saying that edging the kayak, "locks it" in the water. His belief is that if you press (not edge) the kayak against the "water wall" (water pressure) on the non-stroke side, combined with the paddle thrust on the other side, that the kayak will shoot forward (like squeezing a bar of soap) and will run straighter.

His view is that too many kayakers focus on the paddle alone, and this leads to “dragging the boat" -- paddling hard but still achieving poor results/speeds.

I recently replaced my old-style "winged" ICF K1, with a modern epic Legacy K1. Even though I'm pleasantly surprised that the primary stability is better, a K1 is still a twitchy beast as compared to a V12. That makes a K1 great for technique work, because your stroke mechanics are not masked by a stable platform. A stroke in a K1 feels like a dance; you feel every nuance, even minor body movements affect kayak trim and balance.

While the goal, even in a K1, is to keep the kayak running flat and smooth (look at some footage of Greg Barton), the kayak will respond to a big stroke/torso rotation, so for most kayakers, it's not about edging or not edging, but which way you will allow the kayak to lean, and how that affects technique.

You can find examples of kayakers who lean toward, or away from the paddle, so not all coaches agree. In the quote below, Kemecsey is asked a question similar to your comment/video about a paddler who is leaning away from the paddle:
"Top athletes lean the boat to the pulling side gradually starting on the recovery of the stroke on the opposite side. This is because the athlete is twisting and swinging the body from the pulling side towards the opposite side. This movement increases power on the blade locked in the water. The same movement compresses the other side of the boat into the water wall. (This produces the "wet-soap" effect.) Also this boat position gives a firm support on which the athlete can apply a powerful technique. The heel is pressing the hull down on the pulling side. At the same time the opposite leg is relaxed and the knee is rising up".

Some of the concepts that Kemecsey teaches are very interesting. That said, Kemecsey is the first to say that these methods are not scientifically proven (e.g. wet soap effect) -- rather they are what the kayaker *FEELS* to produce top results.

You can’t digest Kemecsey in one sitting. It took me months to really dig into this. Even if you disagree with Kemecsey, I found that thinking through each phase of the stroke, and doing drills to support the movements, helped me to achieve a much better understanding of my stroke.

BTW, you can find additional links on the web, some with images of his “power circles”.

Greg Stamer
Last edit: 12 years 2 weeks ago by gstamer.
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12 years 2 weeks ago #11825 by Kayaker Greg
Replied by Kayaker Greg on topic Re: Leg drive
Is it just me or does the paddler in the last video have a bad catch? But what do I know. :S

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12 years 2 weeks ago #11826 by Kayaker Greg
Replied by Kayaker Greg on topic Re: Leg drive
Thanks for the links Greg, there is great reading there and it makes perfect sense to me. In fact it brings memory's of my skateboarding days where we used to propel our boards with hip and torso rotation and used the frorce of the wheels against the pavement to move forward, same principles as discussed with powering the kayak forward against the wall of water. Its so much more than just the paddle moving the kayak forward, a real light bulb moment for me.

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12 years 2 weeks ago - 12 years 2 weeks ago #11827 by Kocho
Replied by Kocho on topic Re: Leg drive
OK. Thanks for the clarifications, Gregs ;) I think the skating or propelling by twisting and pushing sideways analogy makes sense, at least conceptually. The wind surfing and especially waterskiing analogy in the article did not make that clear for me. Wave surfing, skating, skateboarding, skiing yes, one uses gravity and inertia against the curve of the turn to generate speed in the desired direction of travel by leaning into the turn and pushing against the curve...

Not sure what's the best use of my rather limited power (compared to these top athletes) and whether I can get any direct benefit, but thinking abot the stroke and being conscious of the various phases is a good benefit too. Still can't quite wrap my mind about the application of this concept in forward paddling though... I've been experimenting with something a bit different: during the power phase, as the paddle slices out, trying to find the optimal angle to pull the shaft: it is not straight bak, it is somewhat towards the boat (even though the paddle is slicing out, one needs to counter that with a pull in to generate forward propulsion in an efficient way). So finding the best angle to apply that force for various levels of effort seems like an interesting optimization too. For me, to pull inwards requires a nice twist of the torso and shifting my back away from the paddle, thus possibly a bit of a body lean away from the paddle. If I were to do the pulling while leaning towards the paddle, i'd be using more of my side back muscles rather than utilizing more body rotation... I'm sure there is a balance somewhere there ... ;)
Last edit: 12 years 2 weeks ago by Kocho.

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12 years 2 weeks ago #11828 by Rightarmbad
Replied by Rightarmbad on topic Re: Leg drive
Just a real cursory glance at the videos, I mean real quick, the ones that lean away from the paddling side all seem to me to have long paddles compared to their body.
Maybe they are simply leaning away to try to get the paddle at the most powerful angle of pull to the body.
Maybe that is why there is such a craving to get higher in the boat?

Maybe when you get the length/angle to match your musculature, you stay relatively flat?
As long as the paddle length then matches your speed/cadence equation.

Maybe it is a function of the stability curve of the boat?

Follow the path of the independent thinker. Expose your ideas to the dangers of controversy. Speak your mind and fear less the label of 'crackpot' than the stigma of conformity. And on issues that are important to you, stand up and be counted at any cost.--- Thomas J. Watson

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12 years 2 weeks ago #11830 by gstamer
Replied by gstamer on topic Re: Leg drive

Rightarmbad wrote: Just a real cursory glance at the videos, I mean real quick, the ones that lean away from the paddling side all seem to me to have long paddles compared to their body.
Maybe they are simply leaning away to try to get the paddle at the most powerful angle of pull to the body.
Maybe that is why there is such a craving to get higher in the boat?


Regarding "leaning away", Kemecsey says, "This swinging motion sends more power to the blade than trunk rotation which is produced by abdominal muscle power".

My understanding is that Olympic sprint kayakers use very stiff shafts and fairly long paddles. A study done in 2005, "Equipment Set-up among Olympic Sprint and Slalom Kayak Paddlers", found that for the sprint paddlers tested the paddle lengths ranged from 216.5cm - 223.cm. The mean paddle length was 220.2cm. The mean weight of the male athletes was 84.8kg (186.95 lbs) with a height of 1.845m (6.03 feet). This data is getting old, I wonder if the paddle lengths have started to decline.

As far as seat height goes, it's all about leverage.
In "the Barton Mold", it's stated: "There is a basic trade-off concerning seat height. Generally, the higher the seat, the more leverage, and the "better the attack" (catch) on the water, but the lower the seat, the more stable the boat is". According to this text, Barton's K1 seat is 7cm (2.76") off the bottom and he uses a 1/2" (1.27 cm) foam pad.

Greg Stamer

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12 years 2 weeks ago #11835 by Rightarmbad
Replied by Rightarmbad on topic Re: Leg drive
But how high does a K1 actually sit in relation to the water level?
A K1 sits deeper in the water, it is shorter, skinnier and more rounded profile than ski, so it must sit lower in the water for the same paddler.
So how high does a K1 paddler really sit compared to a surfski?
7cm above the bottom starts out at a deeper level than a surfski.

If I paddle like everybody else, ie look the same with a more 'textbook' stroke, then 223cm works for me, but that's just silly to use in a surf ski.
That's why I simply threw away anything 'normal' and went searching for what worked for me.

Follow the path of the independent thinker. Expose your ideas to the dangers of controversy. Speak your mind and fear less the label of 'crackpot' than the stigma of conformity. And on issues that are important to you, stand up and be counted at any cost.--- Thomas J. Watson

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12 years 2 weeks ago #11836 by Rightarmbad
Replied by Rightarmbad on topic Re: Leg drive
If getting your bum higher than your feet is really so important, why don't manufacturers make an elevated seat option?

Much better than wobbling about on top of a squishy pad because you maintain contact with the bucket.

Can a hull be designed around a deeper foot profile without serious compromises to handling/drag?

Follow the path of the independent thinker. Expose your ideas to the dangers of controversy. Speak your mind and fear less the label of 'crackpot' than the stigma of conformity. And on issues that are important to you, stand up and be counted at any cost.--- Thomas J. Watson

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12 years 2 weeks ago #11837 by Rightarmbad
Replied by Rightarmbad on topic Re: Leg drive
Leverage?

Where is the lever?
How are the forces applied?
Where is the origin point?

That's just an airy fairy statement, which is strange coming from somebody I assume has a good engineering understanding or the boat he designed and I paddle would be shite.


I suspect that the real answer is that nobody really has a great handle on paddling motions as the subject is so extremely complex.

A bit like trying to model a surfski in open water conditions, just too many variables.


Surfski, a past time that can keep you wondering and learning for a lifetime or two.

Follow the path of the independent thinker. Expose your ideas to the dangers of controversy. Speak your mind and fear less the label of 'crackpot' than the stigma of conformity. And on issues that are important to you, stand up and be counted at any cost.--- Thomas J. Watson

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12 years 2 weeks ago #11838 by zachhandler
Replied by zachhandler on topic Re: Leg drive
RAB - would you please go paddling and stay away from your computer for a while. This is all getting a bit tiring. Just because you don't understand something about paddling, you shouldn't come to the conclusion that Greg Barton is wrong in his understanding of kayaking. Likewise you shouldn't conclude that just because you don't understand something, the problem must be too complex for any human to understand. Please I am sick of this. This whole site is turning into your own personal blog. I don't think that is the purpose of the site. You have overstepped your bounds, and you are detracting from the quality of the site. So please, paddle more and post less.

Current Skis: Epic v10 g3, NK 670 double, NK exrcize, Kai Wa’a Vega, Carbonology Feather, Think Jet, Knysna Sonic X
Former Skis: Epic V12 g2, Epic V12 g1, Epic v10 double, Nelo 550 g2, Fenn Elite S, Custom Kayaks Synergy
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12 years 2 weeks ago #11839 by isotopez
Replied by isotopez on topic Re: Leg drive
I think the point is this... the topic is leg drive. If you have any comments that can contribute to the OP's question in reference to leg drive, then post.

It seems like every thread on this forum gets derailed.

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12 years 2 weeks ago #11840 by Kocho
Replied by Kocho on topic Re: Leg drive
OK, Leg Drive observation (back on topic) ;)

Just came back from a quick paddle (about 10 miles) where I tried to work on leg drive. Boy that thing works! And works you out too :woohoo: Whatever these muscles on the sides of my butt are, now the hurt pretty good...

When focusing on driving well with the legs, pushing solidly with the driving leg, raising the knee on the free leg, rotating my butt, it all seems to come together pretty good when the arms are out and high with a good form.

Also, seems that some tilt towards the paddle feels more powerful than tilt away from it. But being relatively flat (no tilting) feels good too... I did not feel any "wet soap" effect, but just the body ergonomics seem to align a bit better for me when flat or with a bit of a tilt to the paddle (especially towards the end of the stroke).

Good thread, thanks for starting it and the videos and reading materials linked!
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12 years 2 weeks ago #11841 by Kayaker Greg
Replied by Kayaker Greg on topic Re: Leg drive
Kocho, the tilt is actually pretty subtle, but should be towards rather than away from the paddle, that's what I was told and is my understanding anyway. And you likely only really get the wet soap effect when really putting the power on. Your probably not going to get it on the first try, or even perhaps with months of trying, its something to aim towards, be aware of and get the circles working for you, much like a beginner can not be expected to understand or get the skateboard moving with no other means but body movement.

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12 years 2 weeks ago #11842 by owenw
Replied by owenw on topic Re: Leg drive
I'm an old (ancient?)seakayaker, who got into flat water racing a couple of years ago and now race a TK2 with my wife or my ski solo. I've had a couple of stroke lessons from a couple of good coaches (ex Olympians) who emphasised proper rotation and full leg drive. It was not until I looked at some photos of me "at work" did I realise that I'm an "away" leaner (see avatar photo) - not a conscious effort, it just came naturally.

Life truly lived is full of risk; to fence out risk is to fence out life itself

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12 years 2 weeks ago #11843 by Kayaker Greg
Replied by Kayaker Greg on topic Re: Leg drive
I think most are until coached to lean on the paddle and lean into it.

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12 years 2 weeks ago #11844 by Physio
Replied by Physio on topic Re: Leg drive

Kocho wrote: OK, Leg Drive observation (back on topic) ;)

:woohoo: Whatever these muscles on the sides of my butt are, now the hurt pretty good...

piriformus

I have been finding the better a paddler is the more knots, trigger points they get in the piriformus and glute med and min. I found this by accident when I was looking for a reason my multisport athletes were getting calf pain/injuries when running after paddling or especially when really good paddlers tried to transition into events with running in.

But how the hip controlling muscles work is as complex as picking the right length hull and shape of a ski for all wave conditions.As they can either externally or internally rotate the leg dependent on the angle of the hip.

I initially suspected the muscle tightness was due to the need to alter hip position as the core rotated , however I am leaning towards it being from a strong leg drive(I dont get it and have a weak leg drive), and if all kocho changed during yr paddle was the drive and are getting pain/tiredness in this region it would support this theory.

If anyone else is out working on leg drive cld they report back what is more tired than usual :) .

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12 years 2 weeks ago #11845 by AR_convert
Replied by AR_convert on topic Re: Leg drive

Physio wrote:

Kocho wrote:

I have been finding the better a paddler is the more knots, trigger points they get in the piriformus and glute med and min.
If anyone else is out working on leg drive cld they report back what is more tired than usual :) .


I will start another thread on paddling related injuries because this could well overtake the leg drive question.


Always looking for the next boat :)

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12 years 2 weeks ago #11847 by Physio
Replied by Physio on topic Re: Leg drive
[/quote]I will start another thread on paddling related injuries because this could well overtake the leg drive question.[/quote]

good call.
i was trying to keep it on topic, but i'm sure everyone has injuries to share. :(

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12 years 2 weeks ago - 12 years 2 weeks ago #11848 by Kocho
Replied by Kocho on topic Re: Leg drive
Well, what I meant was that I had tired in that area more than usual. The pain was not "bad", just good workout result. But you are right - when I got to shore I could feel it strongly when walking or when bending my knees. So, good leg drive and body rotation definitely result in stretching the tissues in that area. Not necessarily a bad thing, but definitely something to work on to build-up strength and flexibility.

On the other hand, my arms did not tire nearly as much as normal after that paddling - the only muscles that really tire are the ones lifting the paddle up. Biceps did not get tired much as I kept my arms well straightened during the power phase. My wrists also did not hurt (sometimes they do when I have poor technique). A good rotation helps with many things ;)

I also had to move my foot place one notch closer to me from where I normally have it - that allowed me to get better stretch of my pushing leg (by the way, that does not result in pushing my butt against the rear of the seat, if you are doing pushing back, that's wasted effort)
Last edit: 12 years 2 weeks ago by Kocho.

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