Help! My SDK is Horrible!

[Chris Stevenson]

Thanks Chris and Fritz, sound explanations.

Chris, there's indeed scientific data available on this topic, I'll spend the next week reading what's available.

Here's a short example where they found out what we already knew: downward beat is far more propulsive than upward beat.
http://www.ncbi.nlm.nih.gov/pubmed/1...m&ordinalpos=1

Thanks for the reference. Here is another I found:

http://www.me.jhu.edu/fsag/Publicati...Afred-JBME.pdf

(Hopefully it works for you; on my work network I have access to a number of journals through institutional subscription and since I'm at work right now, I can't tell right now if that link works for everyone.) I particularly like fig 2. I also found it interesting that efficiency for the SDK was stated to be significantly better than freestyle.

I think there are two main reasons the downbeat is more effective: you engage the powerful quadriceps, and the flex in the ankles means more of the force goes to forward movement. That's why ankle flexibility is SO crucial: I think just a little increase in flexibility can dramatically increase your forward propulsion. If you look at underwater video of Phelps doing SDK, his feet are like a pair of flippers. (Sigh...maybe even more than height, I've always wished to have bigger feet than my puny little 9 1/2s.)

I injured my knee recently (slipped on ice) and for a couple days it hurt to hyperextend. What that emphasized to me was how much I depend on that in my SDK. When I was just cruising it was not a big deal, but when I really tried to kick fast, my knee hurt a lot during the less powerful "upbeat" portion (which is actually a downbeat on backstroke, but whatever).

It made me think about the role of the upbeat in my SDK. Maybe it is important not so much for its propulsion but for kick frequency: I was emphasizing it just to get my legs/feet back for the powerful downbeat part of the kick.

Fritz, I think you are absolutely right about the advantage of being able to see the water on backstroke SDK. It really allows you to time your breakouts better (I switch to flutter kick just before the breakout, for instance). I also think I make subconscious alterations in hands/body to keep in deeper (faster) water based on visual feedback.

One other issue that I think is really important is head position. Ande mentioned this elsewhere, about a "head break." A lot of coaches teach to have your hands in a tight streamline BEHIND the head, but I think that is incorrect. I was playing around in a 50m pool with fins, trying different head positions: the advantage of doing this with fins is that you are going so fast you can really feel the difference when your head is acting as a brake. The most efficient position for me was having your head between the arms, which were maybe JUST behind the ears.

I also think it is important to hold the arms very rigid in the streamline, not just for hydrodynamics but because it gives your kick more leverage.

What all of this brings home to me is the importance of practicing SDK for technique, speed and endurance. And having a race plan -- how many kicks off each wall -- that you train toward. It really is a 5th stroke. (Or, in my case with my lousy breastsroke, a 4th stroke.)

[SolarEnergy]

Thanks for the reference. Here is another I found:

http://www.me.jhu.edu/fsag/Publicati...Afred-JBME.pdf

Thanks Chris, it works beautifully. I will need little time to read and digest all that but at first glance, they seem very serious in their approach. They could measure(?) as opposed to estimate power generated by using special fluids(?).

I think there are two main reasons the downbeat is more effective: you engage the powerful quadriceps, and the flex in the ankles means more of the force goes to forward movement. That's why ankle flexibility is SO crucial: I think just a little increase in flexibility can dramatically increase your forward propulsion.

In total agreement here.

This raises an interesting point though. I'm tired of hearing some coaches asking me to keep my legs together during the whole dolphin kick action. My ankles/feet are built in a way that at the peak of hyper extension, my feet both point toward the inside. There's nothing I can do about it. Therefore, instinctively, to get more extension my legs are not *tied* together on the downbeat.

It made me think about the role of the upbeat in my SDK. Maybe it is important not so much for its propulsion but for kick frequency: I was emphasizing it just to get my legs/feet back for the powerful downbeat part of the kick.

Here I really can't help.

Maglischo clearly says that in his opinion, the upbeat isn't propuslive. That, as of 2003, had not been demonstrated by science yet.

Me? I'm confuse. I feel some propulsion resulting from the upbeat. That is, if I go hard on the upbeat, it seems that it's getting me to move faster. But like you say, it could be a momentum issue. Energy is accumulating during the upbeat and the drastic shift from up to down may create a wip effect.... I really don't know I'm confused.

I was playing around in a 50m pool with fins, trying different head positions: the advantage of doing this with fins is that you are going so fast you can really feel the difference when your head is acting as a brake. The most efficient position for me was having your head between the arms, which were maybe JUST behind the ears.

+1

What all of this brings home to me is the importance of practicing SDK for technique, speed and endurance. And having a race plan -- how many kicks off each wall -- that you train toward. It really is a 5th stroke. (Or, in my case with my lousy breastsroke, a 4th stroke.)

I agree there as well. That's why I'm so unhappy with my 200 at the moment. I have no SDK strategy. I give 1 kick and pull out immediately. I often ask my friends (I do most of my 200s outside squad training) to establish a pace at freestyle for me. Like I ask them to book 200 repeats in 3min then follow in their draft. If I get dropped (which is what happens 80% of the time), it is always after a turn. I just don't have the lungs to SDK hard and long enough to stay in their footsteps.

In other words, my turns suck, and with only 1 SDK * 7 turns, no wonder why my 200 is so bad.

[sjstuart]

Interesting article, Chris, thanks.

I also found it interesting that efficiency for the SDK was stated to be significantly better than freestyle.

Careful, that's apples & oranges. They claimed the "propulsive" efficiency of underwater dolphin kick is significantly better than the "total" efficiency of freestyle. The only number they gave for propulsive efficiency of freestyle is 58% for "quasifreestyle".

What impressed me is how low the efficiency is. The inefficient "male 1", who is nonetheless an Olympic-level swimmer, has to generate 640 W of power to generate 72 W of useful power. I know from playing around with powermeters on a bike that 640 W is working pretty hard -- especially when you're not allowed to breathe!

It would be interesting to know who their models were, so we could compare videos of the SDKs with 11% vs 29% efficiency.

[ande]

"I'm tired of hearing some coaches asking me to keep my legs together during the whole dolphin kick action. My ankles/feet are built in a way that at the peak of hyper extension, my feet both point toward the inside."

Phelps' feet point inward, I think it improves the angle of the foot and increases surface area, think it's a mistake to rigidly point your feet straight

"Maglischo clearly says that in his opinion, the upbeat isn't propuslive."

I think Maglischo is WRONG, I'll stand barefoot on his coffee table and tell him that FAST SDKers get propulsion from the backsweep part of their SDK. I can feel it in mine. I'm sure it's not as much as the down beat, but it helps, it contributes something."

Develop an SDK strategy for all your races, but it can't be a surprise day of the meet decision, you have to know your numbers and do them in training.

You CAN IMPROVE your 200, a faster SDK may be part of your solution, better conditioning definitely is.

Ande

[SolarEnergy]

Ande, I like your last post (as usual). The fear of running out of air during a 200 BF isn't particularly fun, but I am going to have to do something about this.

Yesterday night, same story. That time I tried to get better squats off the wall to see but that wasn't enough. I'm stuck.

As for ankle/feet angles that point inward, it is very true.

Maglischo is the number 1 authority in stroke analysis. However, he has often been wrong over the last 3 decades, correcting himself at every new edition of the book. On the aspect of propulsion generated (or not) during the upbeat of the flutter kick/dolphin kick (he places these two in the same category), he mentions that they are probably not propulsive.

1. I don't think we should confuse dolphin kick with flutter kick. These are two different animals (sharing some common elements)
2. I have a hard time explaining how one could be faster SDKing than swimming full stroke just by relying on the downbeat of the kick as only propulsion

Note that it would be fairly easy to throw his arguments on the floor because of point#1. All he'd (or any other scientist) have to do would be to take a Butterfly/Free Style specialist and ask them to perform a full blown 25y SDK, whilst comparing this with a full blown 25y underwater flutter kick.

[Stevepowell]

[QUOTE=Chris Stevenson;205601]Thanks for the reference. Here is another I found:

http://www.me.jhu.edu/fsag/Publicati...Afred-JBME.pdf

(Hopefully it works for you; on my work network I have access to a number of journals through institutional subscription and since I'm at work right now, I can't tell right now if that link works for everyone.) I particularly like fig 2. I also found it interesting that efficiency for the SDK was stated to be significantly better than freestyle.

Chris, thanks it works for me. Are all the results simulations?

[shane]

if anybody knows about propulsion from the SDK upbeat it should be these guys http://www.swimetrics.com/swimproto.html since they measure this stuff.

maybe somebody here that has been tested could comment.

[Stevepowell]

How do you get the full text for this:?

http://www.ncbi.nlm.nih.gov/pubmed/1...m&ordinalpos=1

[Chris Stevenson]

How do you get the full text for this:?

http://www.ncbi.nlm.nih.gov/pubmed/1...m&ordinalpos=1

Here are direct links to the original articles:

PDF: http://pdfserve.informaworld.com/436041__908689178.pdf

HTML: http://www.informaworld.com/smpp/sec...text=713240928

Again, I may have institutional access thru my university. Hopefully the links also work for you.

Steve, the results from BOTH papers are simulations.

[Stevepowell]

Thanks Chris, Hopefully, now that they have a somewhat accurate model, some trial and error experiments will predict the fastest way to kick. (insert 17 caveats here).

This conclusion was interesting:

"By computing the forces produced by the various segments of the body, we find that most of the active drag during the dolphin kick is produced by the chest, abdomen, and hips, whereas most of the propulsive force is produced by a small portion of the legs extending from just above the ankle to the toes. Thus, a focus on foot motion and ankle flexibility could have a large impact on dolphin kick performance."

[SolarEnergy]

if anybody knows about propulsion from the SDK upbeat it should be these guys http://www.swimetrics.com/swimproto.html since they measure this stuff.

Not sure though that their device could detect velocity changes (if any) that occur during the SDK execution though, otherwise, folks like Maglischo would probably be in a better position to issue a solid statement about this topic.

[shane]

the website claims a sample rate of 60hz for both velocity and force. the stroke rate for SDK is maybe 2 or 3hz, so that should be enough to answer the question.

i am curious about this issue because although i feel my feet pushing water on the upbeat, i can't really say that i feel myself accelerating forward during that phase. of course i could be doing it wrong. i can say that i definitely feel the propulsion from upbeat when using fins. maybe for me without fins there is force created during upbeat but not enough to overcome the opposing drag force.

a while back i was experimenting with this and got the idea to try doing just one upbeat without the downbeat first. like a breaststroke pulldown except use an upbeat instead of downbeat. it was funny and i went absolutely nowhere. on the other hand i can do one downbeat from a dead stop in the water and get a pretty good forward movement. not saying this was an answer but it did give me the feeling that if there is propulsion it must be pretty small compared to downbeat.

[Atlantic]

Maybe it might help to kick on your back for most of your SDKs in freestyle? Then rotate over just before the breakout. I believe Mike Ross does this in his freestyle races. It takes some getting used to; and you do 1-2 kicks during the rotation part, so you need to start to rotate a bit before you really need to surface.

Did this in practice this morning - and I loved it. Taking baby steps here, only did 4 (sometimes 5) SDK's... but my turns felt pretty fierce. I felt quicker and definitely more streamlined off the walls. Thanks so much for your advice!!!

[ande]

let's get back on track, I created this thread to help swimmers focus on their SDK & improve it.


+ Test your SDK speed
+ TRAIN
+ See how much you can improve
+ Report your results in this thread


Anyone game?
Get started.

here's the original post to this thread

SDK stands for Streamlined Dolphin Kick
some people call them "underwaters"

Swimmers use SDK in sprints, 50's, 100's & 200's
free, fly, back and IMs

for several years we've had the

"Help my flutter kick is horrible" thread

It's time for a thread to help people improve their SDK


This is the thread for people who want to improve their SDKs

here's what excellent SDK technique looks like

crocker 100 fl [ame="http://www.youtube.com/watch?v=Ym_ks0aHkCE"]YouTube- Phelps Rallies Past Crocker in 100-fly[/ame]

phelps 200 fl [ame="http://www.youtube.com/watch?v=XlXuJP_9DjA&NR"]YouTube- Phelps Shatters 200-meter Butterfly World Record[/ame]

phelps 200 fr [nomedia="http://www.youtube.com/watch?v=fxKwi341UAs"]YouTube- Broadcast Yourself.[/nomedia]
[ame="http://www.youtube.com/watch?v=r4BYPrO8aG0"]YouTube- Phelps 26-28-30-29 strokes per length[/ame]

phelps 200 IM WR Underwater POV [nomedia="http://www.youtube.com/watch?v=y0cWLZ2bsOc&NR=1"]YouTube- Broadcast Yourself.[/nomedia]

Lochte 200 bk [nomedia="http://www.youtube.com/watch?v=xETC2p461o8"]YouTube- Broadcast Yourself.[/nomedia]

2004 olympics 100 bk [nomedia="http://www.youtube.com/watch?v=NhPYeVfBfKk"]YouTube- Broadcast Yourself.[/nomedia]

coughlin 100 free [ame="http://www.youtube.com/watch?v=ARxQg4NUn4s"]YouTube- Coughlin finishes strongly in 100-meter freestyle[/ame]

coughlin 100 fl [ame="http://www.youtube.com/watch?v=u3cXB2JpFAE"]YouTube- Coughlin wins another gold in the 100-meter butterfly[/ame]

50 back worlds [ame="http://www.youtube.com/watch?v=YrsVG1r6N0E"]YouTube- Vaziri Breaks Women's Backstroke Record[/ame]

100 bk scm lockte WR [ame="http://www.youtube.com/watch?v=ytawE099E8U"]YouTube- Lochte's 100back at short course world championship[/ame]

Klim [ame="http://www.youtube.com/watch?v=q_wbOGDdJGo"]YouTube- Free - Klim[/ame]

thorpe [ame="http://www.youtube.com/watch?v=TbOb6ApepqU"]YouTube- Free - Thorpe4[/ame]


Here's how you improve your SDK

1) test your SDK and find out where you are
get timed for
+ 15 meters or yards from a dive
+ 25 Y/M from a dive and
+ 50 Y/M from a dive
report your results here

2) Experiment to figure out which SDK feels best for you
back, belly or side

3) Experiment to figure out how many SDK's you should take off your starts and turns in races for free, back, & fly

4) train to perfect your SDK technique
streamline and kicking motion

5) train to perfect your conditioning and mental toughness
do very fast SDKs for speed
do 25's 50, 75, 100, 150, & 200 kicks wher eyou improve conditioning

6) train to increase your strenth and power
legs and core work, weight training pilates exercises

7) train to increase flexiblity
streamline and ankles

8) be consistent and patient, stick with it for at least 3 or 6 months

9) retest and track your improvement,
REPORT YOUR RESULTS IN THIS THREAD

10) do the experiment again
as your SDK improves you can take more SDKs in your races

11) remember to keep up your SDK speed training as you taper and prepare to race


good luck
hope you SDK Faster Faster
Please report your progress
contribute and encourage

Ande

[letsrace]

To Chris' point about shallow pools, there is no doubt shallow pools make doing SDK more complicated and I would argue less effective. I no longer even expect to have fast times in shallow pools because it messes with my trajectory. Could this be improved by kicking on one's side? Yes, but I still don't think it is as fast as on back.

Chris makes the point about putting the head back in the arms in the underwater kick. I wholeheartedly agree. Drag is the main reason, the other reason relates to flexibility. When I watch swimmers who kick under water by pulling their head out of their arms, meaning arms squeezed tight behind their head, I think they look less comfortable kicking. To me, "less comfortable" equates to less power.

Regarding the effectiveness of an upbeat (or downbeat from my perspective). This is simply anecdotal, but I was taught 20 years ago that it is not important and I have seldom considered it in my kicking since then. I recognize that this is a very small sample size. Perhaps, the effectiveness of the upbeat kick is based on the structure of one's legs. I will say that I have room in my "philosophies" to believe that I could improve by focusing on the upbeat.

On toes pointing in and hyper-extension of the knees. I maintain that if I was going to pick out fast kickers walking along the street, I would choose pigeon-toed individuals who could lock out their legs with their knees hyper-extended. I have witnessed a lot of fast kickers who were structured this way.

SolarEnergy brings up two points:

1. I don't think we should confuse dolphin kick with flutter kick. These are two different animals (sharing some common elements)

Absolutely. Flutter kick is not two legs doing dolphin kick independently. Each leg is limited by the counter movement of the other so that the body can't get involved at the same level as in dolphin kicking.

2. I have a hard time explaining how one could be faster SDKing than swimming full stroke just by relying on the downbeat of the kick as only propulsion

On the second point, I am not as mystified. Just because the SDK might be missing a downbeat does not necessarily mean that it should be slower than a full stroke. As someone else pointed out to make another argument, it is "apples to oranges". The SDK can generate more power because of greater resistance and can be more efficient than swimming on the surface. Missing the downbeat only means that the SDK could, in theory, have more power.

[SolarEnergy]

9) retest and track your improvement,
REPORT YOUR RESULTS IN THIS THREAD

All right coach. I will do.

Sorry for the distraction, I always talk too much. Blame it on passion.

I'll start assessing the 25m fast SDK as early as tonight.

[SolarEnergy]

On the second point, I am not as mystified.

I'll quickly tell you why I am still wondering about all this.

Take fins. Perform SDK. You get this feeling that every beat is helping forward propulsion right? You clearly experiment the feeling and it's not only a feeling. It's a fact.

I get the same feeling even without fins. That's why I'm still confuse...

The opponents (those who state that upbeat isn't propulsive) as the same explain that the efficiency of the downbeat is caused by the angle of attack the feet have (thanks to ankle flexibility). To me, it's much easier to get a very sharp angle of attack on the upbeat since the feet naturally flex this way. So I plan to remain confuse until I read solid scientific evidence on the matter.

[fritznh]

I'll quickly tell you why I am still wondering about all this.

Take fins. Perform SDK. You get this feeling that every beat is helping forward propulsion right? You clearly experiment the feeling and it's not only a feeling. It's a fact.

I get the same feeling even without fins. That's why I'm still confuse...

The opponents (those who state that upbeat isn't propulsive) as the same explain that the efficiency of the downbeat is caused by the angle of attack the feet have (thanks to ankle flexibility). To me, it's much easier to get a very sharp angle of attack on the upbeat since the feet naturally flex this way. So I plan to remain confuse until I read solid scientific evidence on the matter.

When I use fins and do SDK, I find that the thrust is more even on the up and down beat. I still get something on the downbeat without fins, however it is not as much as the upbeat. You can engage a lot of big muscles during SDK (core, quads) and the more streamlined you are, the more you can take advantage of the thrust. I'd think that is the main reason that underwater SDK can be faster than swimming on the surface.

One reason for improved thrust from the up kick is that when you begin the kick your knees are bent so that the feet can be nearly perpendicular to the direction of motion, producing much improved thrust, like a fan or propeller blade. On the down sweep, you don't get the same leverage. But I'd maintain that you get something.

The paper from von Loebbecke was interesting, though the analysis was done such that the boundaries would have no effect. Still, to me it shows that there is a lot of improvement to be had with technique. Interaction with boundaries is not covered, mostly because it is far more difficult than lift and drag around a moving body. Free surface modeling in a CFD sense is extremely difficult to do accurately, because you don't know where the surface will be apriori and it is part of the solution. That would tell you how deep you need to be to minimize drag, but nobody's done it yet.

[SolarEnergy]

When I use fins and do SDK, I find that the thrust is more even on the up and down beat. I still get something on the downbeat without fins, however it is not as much as the upbeat. You can engage a lot of big muscles during SDK (core, quads) and the more streamlined you are, the more you can take advantage of the thrust. I'd think that is the main reason that underwater SDK can be faster than swimming on the surface.

My favorite kick at butterfly is this one here
[ame="http://www.youtube.com/watch?v=-p15jmC95ZI"]YouTube- Fly DrillSide[/ame]

Tonight, having Ande's thread in mind, I tried few hundreds. First one, usual energy, did 1:55. Wasn't pleased at all.

Then one with 4 to 5 counts of hard sdk on my side (shallow pool) and more power (especially downbeat as usual) did 1:47. Quite better I thought.

Then I did one hard sdk on my side (4 to 5) and I went all out on upbeat as well as on downbeat (of course) did 1:33. That is what I used to do before.

That said though. Chris may be dead right on the fact that going hard on upbeat may simply give your downbeat more power. And it certainly helps getting the rate going too. Logically, if you go hard on upbeat it gives your SDK more amplitude at equal rate or faster rate same amplitude.

So we all may be right, no matter the point of view. It may not be propulsive but it gets you to move faster.

[ande]

Are you working to improve your SDK?
What are you doing?

How's it going?

Just taking 12 minutes out of each practice to do

8 x 25 SDK ALL OUT for time on 1:30
can help you improve

Here's something that might inspire you

The Morning Swim Show, April 6, 2010:
Tom Shields Analyzes Debut at NCAA Championships
Tom Shields has an outstanding SDK. He won the 100 fl at Mens NCAAs

1 Shields, Thomas CAL
44.91P
r:+0.81 9.57
20.83 (11.26)
32.45 (11.62)
44.91 (12.46)

As a high school freshman tom Shields saw Michael Phelps SDK at a Grand Prix meet at Long Beach and thought to himself:

"I want to be really good at that."

Then he practiced and became great.