Friday, December 14, 2012

The Data On Stroke Rate And Efficiency

We know that quite a few of you like a bit of science behind your swimming, so lets take a look at an important piece of research conducted by Southwestern University, Texas [1]. Even if you're not a numbers person bear with this - it's not too complicated!

Scott McLean and his team asked ten college swimmers of a range of abilities to swim in a flume tank (an endless pool). The flume was fixed to a speed of 1:40 /100m so no matter what, the swimmers had to maintain that speed, they couldn't slow down or speed up.

As a starting point, the study recorded the swimmer's natural stroke rate - i.e. how many strokes they take per minute (SPM) at 1:40 /100m. If you own a Tempo Trainer Pro or Wetronome you will have a good idea of what yours is, most age group swimmers are in the range 50 to 65 SPM.

Each swimmer was then asked to swim at 10% below their natural stroke rate and 20% below it, controlled by a Tempo Trainer beeping the timing to them. Since the actual swimming speed was fixed at 1:40/100m, as they slowed their stroke cadence they had to lengthen their stroke to maintain their speed.

For each swimmer they also sped up their stroke rate to 10% and 20% above their natural stroke rate. To keep the same speed, the swimmer had to shorten their stroke.

For each test oxygen uptake, heart rate and perceived exertion (how hard it felt to the swimmer) where recorded to give an indication of economy. They also recorded the kick rate (kicks per stroke cycle) and to keep the study fair the order of the tests was randomised.

OK that's the technicalities, what did the results say? First lets look at what happened as the swimmers lengthened out their strokes at a lower stroke rate. If you believe that a longer stroke is more efficient, then we'd expect the swimmers to become more economical:

The fascinating result was that as the stroke lengthened, oxygen uptake, heart rate and perceived exertion all rose significantly. The kick rate also increased significantly, suggesting the swimmer had to start kicking harder to maintain speed in the dead-spot created between strokes. All of these things are strongly suggesting that trying to maximise stroke length makes you less efficient, not more efficient.

Now let's add the data onto the right side of the graph as stroke rate increases:

Heart rate, oxygen uptake and perceived exertion all dropped slightly at a 10% increase in stroke rate and then rose a little at a 20% increase. When you get into the maths, the increases at 20% above natural stroke rate are not statistically significant but the mean does rise.

Our Conclusions

1) Swimmers tend to naturally select the slowest stroke rate from the range that is economical for them.

2) Don't overly lengthen your stroke below that point by trying to over-glide, it actually makes you less efficient, not more.

3) You are likely to be able to lift your stroke rate by 10% without losing any efficiency and for some swimmers as much as 20%. In open water the ability to swim at a higher stroke rate is a huge advantage as it helps you punch through wake and chop created by other swimmers. Try and overly lengthen your stroke in open water and you can literally be stopped dead in the gap between your strokes and you will slip to the back of the field despite working hard.

4) The increase in kick rate with longer strokes correlates well with what we see in the elite swimming world where Smooth swim types with a long stroke style (e.g. Ian Thorpe, Michael Phelps, Ross Davenport) use very powerful kicks to help power them through any gaps in propulsion. The thing you don't want to attempt is a long over-gliding stroke with a two beat kick as you simply decelerate far too much between strokes.

Swim Smooth!

[1] McLean SP, Palmer D, Ice G, Truijens M, Smith JC. (2010). Oxygen uptake response to stroke rate manipulation in freestyle swimming. Med Sci Sports Exerc., 42(10):1909-13.

40 comments:

Paul D. Panaretos, S.J. said...

Thanks for a most helpful post! Amazing how tweaking can offer so much. I understand better the drawbacks of _glide_.

Guppie (Defunct Economist) said...

You article prior to this was about increasing your stroke rate. Now an article that states increasing stroke rate may not be efficient. I'm new to all this swimming data, so I am I missing something here.

Chesters said...

SS - you are becoming obsessed with high stroke rate. This is clearly in opposition to the perceived threat of the Long Stroke style propounded by TI.
I am sure fast, long strokes are best of all - it must be a matter of individual optimisation.
Gliding may not be correct racing but it does allow for a better feel of the water and sensation of bad drag etc that can be disguied by a frantic stroke rate.

Anonymous said...

I am both analystical and athletic with only a rudimentary understanding of swimming. I swim 2-3 times per week,usually going 1000-1500 yard within a 30 minutes. So this article tells me to shorten my strokes and kick harder?

Anonymous said...

I realize this may just be one exception, but how you do account for a swimmer like Sun Yang who has a long and slow stroke, and also doesn't kick hard?

Adam Young said...

Hi guys, it's an interesting study isn't it and one that capturing a lot of interest already!

Hi Guppie,

It's all about degrees. The study shows that the 10 swimmers could increase their stroke rate by 10% without losing efficiency (in fact the indication is they gained some efficiency). Last week on the blog we talked about raising your stroke rate by 5 strokes per minute and for most swimmers that's going to be in the 8-10% range.

The other thing we did on the blog last week was help you improve your catch technique before trying to lift stroke rate and that will help even further. The swimmers in this study weren't given any coaching like that.

Hi Chesters,

I don't know about TI but we had some interestingly discussion with them recently and I understand they don't teach an elongated glide any more. Whatever, it's certainly strong evidence against trying to swim with an overglide isn't it? The danger isn't doing it as a drill as you suggest but that the deadspot gets imprinted so the swimmer can't remove it, that is an experienced shared by most overgliders, timing changes like that are incredibly hard to shift once imprinted. And of course, we're not talking about getting frantic either - is just a matter of degrees, getting a rhythm into the stroke is a key ingredient for great freestyle.

Hi Anonymous1,

No definitely not, what it says is in the conclusions - predominantly be wary of overly lengthening the stroke as it will make you less efficient. And that most swimmers have some headroom to add a bit more rhythm without losing economy which is especially useful for open water swimming. How hard you should kick depends on the distances you are racing - sprinters and short distance athletes like those we mentioned do kick very hard but for most of us interested in fitness or distance swimming, we should kick more gently. Just don't combine a very gentle two beat kick with a gliding stroke, that's not efficient swimming and not what elite swimmers do.

Hi Anonymous2,

Sun Yang certainly is an exceptional athlete with super-long arms! When you see him swim (I have up close) he certainly looks like he's gliding by virtue of the sheer length of his stroke but when you study his footage he doesn't at all - there's only 0.15 second between one stroke finishing at the rear and the next starting.

With his kick, he does in fact kick very hard when racing over shorter distances just like thorpe and phelps: http://www.youtube.com/watch?v=nIlHQWPdBec

Cheers!

Adam

Anonymous said...

Something doesnt add up but there's not enough data to analyze.

Elite swimmers use 16-24 strokes per 50m or 32-48 per 100m. Speed = strokes * stroke time. If a swimmer takes 50 seconds and uses 40 strokes (just over world record pace for easy figuring) his stroke time is 50seconds/40strokes or 1.25 seconds per stroke and 60/1.25 = 48 strokes per minute. 100m/40 strokes = 2.5m stroke length.

The case of 65 spm = .92 sec/stroke. At 50 sec/100m with a rate of 65 spm 50/.92 = 54.35 strokes. 100m/54.35 gives 1.84 for stroke length. Its plasuible but thats a pretty high stroke rate and increasing it seems unlikely.

I swim a 100 in 1:40 using 40-44 strokes but my rate is 24-26 spm. i.e my stroke length is fine but I cant go faster because my stroke rate is low. when my rate goes up my length goes down and I actually swim slower. My trouble is Im weak in the upper body.

Sol said...

More great work guys. I've been working with a Swim Smooth coach on and off for 18 months now. Between September 2011 and April 2012 we took exactly 5 mins out of of my 1500m PB and one of the contributing factors was an increase in stroke rate of around 15%.

Anonymous said...

Really interesting study. Quick query. Decreasing stroke rate = increased time between breaths. Could a build up of CO2 / decrease in O2 in the blood (both of which would result in an increased HR and increased O2 uptake) be partly responsible? Were the swimmers bilateral breathing or breathing every two strokes?

Adam Young said...

Hi Anonymous3,

You're mixing your units. When we say 65 SPM we're counting both arms but when you say 16-24 strokes per 50m you're counting cycles, they actually take 32-48 strokes.

Hi Anonymous4,

My understanding is that the swimmers were breathing through a mouthpiece and tube for the VO2 rig so they could breathe whenever they wanted. So decreasing the stroke rate shouldn't change the breathing rate...

Anonymous said...

Anon3 here:
ahh, a case of the halves and halve nots... :-)

on another point, it's been my belief that instantaneous speed and distance per stroke builds (increases) throughout the length of the pool in a short course pool. Would you agree with that observation? I would assume in a long course pool maximum speed is reached at some point.

Adam Young said...

Good stuff Anon3. Fastest speed is at the push off and swimmers decelerate throughout the lap, stroke slightly shortening as they go... Sorry! :D

Anonymous said...

Anon3 again...
well... it certainly feels as though im going faster near the end of the length. I guess that points to some deficiencies in my 9month swimming career. I suspect I may be trasnitioning from pushoff to stroking a bit late. :-(
If only they allowed video recording at my pool I would halve solve this already. :-)

Senior Coach said...

This study is flawed.

The attempt to eliminate variables in individual's stroke by keeping swimming speed constant, actually introduces variables.

How can someone change their stroke rate and swim at the same speed without changing their stroke significantly?

You may read into the results and draw conclusions but they cannot be scientifically correct.

Please look at this study with interest but take the results with a pinch of salt.

Adam Young said...

Hi Senior Coach,

I guess we'll have to agree to disagree! Sure these studies are very hard to conduct perfectly but in my opinion there's some good conclusions that can be drawn from this one.

> How can someone change their stroke rate and swim at the same speed without changing their stroke significantly?

Yes indeed, and that's the point, the stroke changes and the economy of that is what we are looking at.

Many swimmers are told to slow things down and lengthen things out to the maximum. Of course they slow down when they do this normally, so it's hard to tell if they are more efficient as going slower is always going to feel easier. This study forces the swimmers to maintain their speed and therefore we get an insight into their economy.

The other point of interest here is that we recommend swimmers add a touch more rhythm in open water - and this study shows that when they do that they can maintain their economy perfectly well.

No study is perfect but this one is definitely useful!

Adam

Senior Coach said...

> Many swimmers are told to slow things down and lengthen things out to the maximum.

Hi Adam,

IMO, that is not swimming, that's drilling.
I'm sure you'll agree, it is a very useful drill to swim distance per stroke but in order to achieve the best efficiency one has to spend time in the pool swimming sets, looking at the clock, counting strokes, monitoring heart rate and developing a stroke. Developing a stroke.

A stroke cannot become efficient for an individual within a few minutes of changing it, in fact I would say it takes months or even longer to settle into a stroke after changes are made.

What I'm sure we can agree on is that there is no,'one stroke fits all'.

While you can apply trends to strokes it is misleading to suggest that one can gain efficiency by increasing stroke rate, just as it is misleading to suggest the same about decreasing it.

There are many schools of thought on swimming, it helps to look at as many as you can, try bits out, mix and match, find what works for you and develop your own style. Focus on your drills and let your swimming happen.

If you are serious about swimming fast, I believe it is best to look at those who are doing it and gain advice from those who coach them.

Regards
Mark

Ermie said...

Paul has increased my stroke rate in the last few years and we have compared the relative speed achieved with different stroke rates. I am swimming faster than I have for many years and feeling much better in the water. Less kicking means more endurance in longer swims.
Demonstrates that even at 60 there is room to improve!

Unknown said...
This comment has been removed by the author.
Unknown said...

I believe this study is completely irrelevant to the TI method. If I swim with tempo trainer at 140, I will have a certain stroke rate to maintain that speed. If I set tempo trainer to 130 (faster beeps), my stroke rate would go up. If I changed my stroke length at 140, I would be introducing inefficiencies, so of course I would use more energy. Also, many criticize TI method because they say the gliding causes a loss of forward momentum. Your gliding in a fluid and your stroke rate keeps you in a continuous glide. If your stroke rate is very slow, sure you will slow down and this is very inefficient. Watch dolphins, they move effortlessly though the water and they are constantly gliding.

Anonymous said...

This is an interesting study, but some important information seems to me missing, or maybe it's implied - but implied info makes the study very subjective and wide open to scrutiny as noted in many previous comments.

First what is an "over glide"; Is this constant, or something unique for each swimmer? And if unique, what and how much distance per stroke puts a swimmer into this over-glide category?

Second, not knowing whether these "college swimmers" have experienced slowing down stroke rate or slower tempo, what changes to their stroke cause the additional energy use and consumption of o2?

Third, swimmers that have never attempted to swim at slower rate, in drill or otherwise, tend to kick faster to make up for lack of balance at slower speeds, fast kick burns up a lot of o2. What was the swimmers kick - fast un-timed flutter, 2bk, 4bk, 6bk?

Lastly - are the "college swimmers" on the college swim team or college students that swim recreationally for fitness? How many swimmers in the test and swim level of each? What range did most subjects fall?

Unknown said...

Great questions Anonymous, hopefully there will be more studies that will help answer these questions.

Adam Young said...

Hi Senior Coach Mark,

OK, I think we're much more on the same page now. Yes, I would call that a drill too but unfortunately many don't and as I said earlier, the glide becomes heavily imprinted. We've seen it with 1000s of swimmers every year.

> A stroke cannot become efficient for an individual within a few minutes of changing it, in fact I would say it takes months or even longer to settle into a stroke after changes are made.

Yes of course, which is why it makes the slight increases in efficiency at a slightly higher stroke rate all the more impressive.

The problem with giving each swimmer some swim sessions to adjust is their fitness would change over the time-frames so we're in that situation where the perfect study is impossible but we can certainly see a lot that can be learnt from this one.


Hi Unknown,

> If I swim with tempo trainer at 140, I will have a certain stroke rate to maintain that speed.

Are you confusing stroke rate (strokes per minute) with stroke length (strokes per length)? The beeper is controlling your stroke rate so that's it. I'm not sure but perhaps this misunderstanding is confusing your reading of the blog post.


Hi Anonymous,

> First what is an "over glide"; Is this constant, or something unique for each swimmer? And if unique, what and how much distance per stroke puts a swimmer into this over-glide category?

We measure glide as the time between one stroke finishing at the rear and the next starting at the front. This is the time without propulsion in the stroke - or the glide time. Elite swimmers are in the -0.1 to 0.2 second range (negative being an overlap with the front stroke starting before the rear finishes).

A classic Overglider is in the region of 0.4 to 0.6 seconds of glide and an extreme Overglider 0.7 to 1 second or longer.

You can read more about it in our classic blog post here: http://www.feelforthewater.com/2012/03/overgliding-inefficiency-and.html

If you ask a swimmer to use a longer and longer stroke they are forced to add this inefficient glide into their strokes.

It doesn't have anything to do with the stroke length, some Overgliders actually have quite short strokes despite trying to really emphasise glide.

> Second, not knowing whether these "college swimmers" have experienced slowing down stroke rate or slower tempo, what changes to their stroke cause the additional energy use and consumption of o2?

It's the deceleration between strokes which means they have to re-accelerate on the next stroke which is very hard work. Or they have to kick hard to avoid the deceleration. Having a deadspot between strokes is inherently inefficient. The accel-decel style also creates a higher peak speed for the same average speed which means drag force is higher on average.

> Third, swimmers that have never attempted to swim at slower rate, in drill or otherwise, tend to kick faster to make up for lack of balance at slower speeds, fast kick burns up a lot of o2. What was the swimmers kick - fast un-timed flutter, 2bk, 4bk, 6bk?

They weren't at slower speed, they were at the same speed. No, the reason they kicked faster was to stop themselves slowing down in the gap between strokes. The swimmers kicked however they felt they wanted or needed to, no control in the study. This makes it closest to the real world situation of a swimmer experimenting and adjusting their stroke length.

> Lastly - are the "college swimmers" on the college swim team or college students that swim recreationally for fitness?

They are training with the university squads so potentially competitive swimmers although I understand they are a range of different ability levels within that. No, not recreational swimmers.

> How many swimmers in the test and swim level of each? What range did most subjects fall?

I can see your questions are going to keep coming so with all respect I think you're going to have to dig out the study and read it yourself. :)

Adam

Stefano D said...

Thanks for the excellent article and post. Single stroke efficiency (pool length left behind per single stroke) is despite all a key issue, right? Besides a technically good catch (for me this translates in early high elbow and vertical arm "pushing backwords" or holding the water for pushing the slightly rotated body beyond the holding arm) and an effective kick, what are the elements that make the difference? Looking at good swimmers in my pool (local competitive A-swimmers) they have at least the double speed at similar rhythm. This means, their stroke efficiency is much better than mine. Are their catch so much better and their kick so much more effective?

Unknown said...

Hi Stefano, I believe swimmers that swim faster at the same stroke rate is because they are swimming more efficiently. Their bodies may be more streamlined and have better rotation in their hips that allow for more energy transfer into the glide. Swimming technique is a complex subject. For myself, I'm interested in making my body as streamlined as possible, like a torpedo, and swim as relaxed as possible. I'm personally not interested from getting to the other side of the pool as quickly as possible. A sprinter would have a much different technique.

Unknown said...

Also, breathing technique is very important. Improper head movement when taking a breath can misaligned the body momentarily, causing one to lose propulsion. Some swimmers sink as they exhale which also causes loss of propulsion.

Anonymous said...

Adam wrote:
" No, the reason they kicked faster was to stop themselves slowing down in the gap between strokes. The swimmers kicked however they felt they wanted or needed to, no control in the study. This makes it closest to the real world situation of a swimmer experimenting and adjusting their stroke length."

I agree real world for swimmers that need to kick more at slower speeds due to lack of balance. And you missed the question, "what caused the the deceleration; just hanging out in a glide? But if you didn't monitor the kick where most o2 goes, how can this study be objective? Unable to answer what range most swimmers fall into. Where is the link or reference to the this study, not the generalized version on the SS web? Thanks.

Unknown said...

I did find the heart rate statistics interesting. I didn't now that the heart rate was that high while swimming. It would be interesting to monitor ones heart rate with ones stroke rate. One then can work on lowering their heart rate by swimming more efficiently.

Unknown said...
This comment has been removed by the author.
Unknown said...

To Adam Young,

Yes, I guess my statement was confusing, the tempo trainer defines the stroke rate. In my swimming I try to increase my stroke length by improving my technique. This is a life time quest. I believe that one benefit of this study is that most people seem to see it as flawed, so maybe the next study will be an improvement.

Adam Young said...

Hi Stefano D,

Yes, low drag and good propulsive technique are the keys to an efficient freestyle stroke. That might end up with a long stroke style or it might not, it depends on the individual swimmer - be very wary of equating stroke length to efficiency, it's actually a very poor measure of efficiency when you study it carefully. With those good swimmers in your pool, try counting their strokes per length and compare that to your count, it's worthwhile to know the actual difference, it might not be as dramatic as you think. Also if you can, compare their stroke rate (strokes per minute) with your own. My expectation is that their strokes are longer than yours and also faster stroke rate.

My suggestion for yourself is to focus on reducing your drag and improving your catch technique - don't try and focus too much on stroke length or this can actually harm your catch and propulsive technique. Aiming for a-long-stroke-at-all-costs causes swimmers a great deal of problems in practise.

Their kick technique might be better yes, although it's unlikely what you need is more propulsion from the kick - take a read of this article to see what I mean: www.swimsmooth.com/kick


Hi Unknown,

> For myself, I'm interested in making my body as streamlined as possible, like a torpedo, and swim as relaxed as possible. I'm personally not interested from getting to the other side of the pool as quickly as possible. A sprinter would have a much different technique.

Many swimmers do this, slow things right down and feel they are more efficient as a result. Are you sure you're more efficient though? Swimming slowly is always going to reduce drag power dramatically as it relates to the cube of speed and makes it feel easier for that reason. But that doesn't mean you're more efficient, it just means you're swimming slowly. The reason this study is interesting is that it forces the swimmer to sustain the same speed with different stroke style so we can a better look at efficiency.

> Some swimmers sink as they exhale which also causes loss of propulsion.

Sorry, could you take me through that one?


Hi Anonymous,

> I agree real world for swimmers that need to kick more at slower speeds due to lack of balance.

As I said before, the speed is the same, they didn't slow down.

> And you missed the question, "what caused the the deceleration; just hanging out in a glide?

I answered that one earlier in this thread. Yes.

> But if you didn't monitor the kick where most o2 goes, how can this study be objective? Unable to answer what range most swimmers fall into. Where is the link or reference to the this study, not the generalized version on the SS web? Thanks.

You didn't read the blog did you? The reference to the study is at the bottom where references always are and is referenced at the start of the blog.


Hi Unknown,

> I didn't now that the heart rate was that high while swimming. It would be interesting to monitor ones heart rate with ones stroke rate. One then can work on lowering their heart rate by swimming more efficiently.

Yes indeed but maintain your speed whilst doing so (as I said above, if you drop your stroke rate and swim slower, that doesn't really tell you anything about efficiency). I'm going to suggest how to do this to one of the other posters below.


Hi Unknown,

> I believe that one benefit of this study is that most people seem to see it as flawed, so maybe the next test will be an improvement.

Actually we've received a huge wave of positive feedback on this post so it's been very well received. It's received 14 shares on facebook, numerous retweets and over 150 of the blog emails have been opened over 20 times (which suggests it's been forwarded to a training group or squad). We're very happy with the reception to it.

Adam Young said...

EVERYONE,

If you feel this study is flawed then try it with your own swimming. Use a Wetronome or Tempo Trainer and swim at a middle-range stroke rate for you (say 60SPM) and record your time over 200m. Then lower your stroke rate by 10% and swim another 200m trying to match the time and then drop it by another 10% and match it again. How does it feel in terms of effort? Give yourself all the time in the world to adapt to any stroke rate and then repeat the whole experiment (including the original 200m).

As I said above, drag force is related to the square of speed which means that drag power (watts) is related to the cube. The drag power is what relates to your effort (HR/VO2 uptake etc) not the force. So effort is inherently very non-linear with speed and therefore by swimming slower things will always feel easier. You must sustain your speed to know if you're really more efficient or not.

Hope that helps!

Adam

Unknown said...
This comment has been removed by the author.
Unknown said...

Hi Adam,

"drag power (watts) is related to the cube"

I never thought of it that way, so lowering drag is the most important component to swimming faster and more efficiently. This is also what my coach has me work on, better technique to lower drag, not a longer or harder pull or faster stroke rate.

I consider myself an intermediate swimmer. One problem I have had and other beginning to intermediate swimmers have related to me is that after swimming some distance, they become tired and start breathing heavily. When I slow down because of fatigue and exhale, my hips and legs drops a little. I need to build up my endurance and core strength to keep a constant velocity.

Since lowering drag seems to be the most important factor in faster and more efficient swimming, changing ones stroke rate and stroke length while maintaining a constant velocity seem unnatural. The way I understand the study, if I increase my stroke rate by 20% I would have to decrease the length of my pull and/or decrease my pull speed to maintain the same velocity - is this not correct.

According to TI studies, which some may disagree with, there is a pull length that is optimal. A pull too long, some of the energy is wasted since some of the pull energy is not directed to the back wall. A pull too short, one is not taking advantage all the energy to push one forward.

Anonymous said...

Great post, love the technicals. BUT.... it occurs to me that I don't have to increase stroke length to maintain speed at a slower stroke rate. A change in body form to less resistance can do the same thing.
As I've been tinkering with all this over time, I'm now appreciating that most of us have marginal form in the water, or better said, most of us do not hold body form like elite swimmers. Recently, I've had some 'faster than expected' sets simply by changing form to more streamlined, while maintaining the same stroke method/rate. The hard part is learning and keeping the improved form.

Peter said...

Dear Adam,
I found the report to be very interesting and would not call it 'flawed', even if one of course must not draw too many or too large conclusions from such a small study.

There is however one issue that I have not quite straightened out. If I am to perform my usual stroke at a higher rate, this should in theory mean that my speed increases, and most definitely my percieved effort. This is of course not the case, not only based on the results from the study but also from my own experience and a wealth of information from elsewhere. If I try to increase my stroke rate slightly I find it easier to find a nice rythm and stroking does not feel tougher as it maybe would. I must therefore be introducing some kind of change to my stroke.

So my question would be: if I want to shorten my stroke, in what part of the stroke do I introduce changes? Should I rotate less? Stretch less? Catch sooner? Push back less?

This question is not really about _me_ and _my_ stroke mechanics, it is more suitable to a Mr Smooth type, who already has an optimized, slick, rhythmic stroke. What stroke changes would Mr Smooth have to introduce if he was forced to increase his stroke rate?

I am not a very proficient swimmer and I apologize if this question is off topic or outside the bounds of this very interesting conversation.

Peter said...

"...shorten my stroke..." in the third paragraph in my previous comment should be be read "increase my stroke rate", sorry for that.

Adam Young said...

Hi unknown,

> I never thought of it that way, so lowering drag is the most important component to swimming faster and more efficiently. This is also what my coach has me work on, better technique to lower drag, not a longer or harder pull or faster stroke rate.

OK, it's so easy to get the wrong end of the stick here. Of course, lowering drag is important in swimming but any swimmer, of any level, still has plenty of drag as there's diminishing returns to it. Your propulsive technique (not working hard but working better) is very important because it's easy for 90% of your effort to go to waste and for it not to contribute to pushing you forwards. This is a huge inefficiency and working on improving your catch and feel for the water is very important for all swimmers, not just advanced ones.

The reason I mentioned the cube drag power relationship is that by adding a pause-and-glide into your stroke you decelerate more between strokes. This means that to swim at the same average speed, you have a higher peak too - the stroke is a constant accel-decel-accel-decel. Unfortunately the higher peak speed of swimming with this style adds a hugely disproportionate amount of drag due to the cube relationship, making it less efficient overall - as show by the results of this study.

> The way I understand the study, if I increase my stroke rate by 20% I would have to decrease the length of my pull and/or decrease my pull speed to maintain the same velocity - is this not correct.

If you cut out the pause-and-glide then you don't have to do either, you can still use your full stroke length. And the bonus is that each arm pull can be easier because you don't have to re-accelerate yourself after slowing down during the glide which is very hard work. Plus you have a lower peak speed for the same average speed, which as I said above is another major factor in becoming more efficient.

> According to TI studies, which some may disagree with, there is a pull length that is optimal. A pull too long, some of the energy is wasted since some of the pull energy is not directed to the back wall. A pull too short, one is not taking advantage all the energy to push one forward.

I'm not sure that TI have ever published a study but please do link to it if they have. We're not advocating shortening the arm pull, just removing the glide.

Adam Young said...

Hi Peter,

> If I am to perform my usual stroke at a higher rate, this should in theory mean that my speed increases, and most definitely my percieved effort. This is of course not the case, not only based on the results from the study but also from my own experience and a wealth of information from elsewhere. If I try to increase my stroke rate slightly I find it easier to find a nice rythm and stroking does not feel tougher as it maybe would. I must therefore be introducing some kind of change to my stroke.

It's possible you are changing your stroke but you actually don't have to. Just by keeping the same stroke you can become more efficient because you develop a better attachment to the water during the catch (less slipping) and also decelerate less between strokes, which also makes you more efficient.

> So my question would be: if I want to shorten my stroke, in what part of the stroke do I introduce changes? Should I rotate less? Stretch less? Catch sooner? Push back less?

Catch sooner but still extend fully before you do, the important thing is not to pause-and-glide when at full extension. Think about keeping your lead hand constantly in motion, either extending forwards, tipping downwards, catching the water or pressing backwards. You don't have to hurry to do this, quite the opposite you have more time because adding a pause in means you have to then hurry the catch, which slips water.

Also, work on improving your catch technique. A poor catch presses the water downwards, which takes some time because water is so dense, this inherently slows down your stroke. A good catch presses the water backwards and this takes less time because you are in a sense just helping the water on it's way and so your stroke rate and rhythm inherently increase with a better catch technique.

> This question is not really about _me_ and _my_ stroke mechanics, it is more suitable to a Mr Smooth type, who already has an optimized, slick, rhythmic stroke. What stroke changes would Mr Smooth have to introduce if he was forced to increase his stroke rate?

I did actually answer it for a swimmer like yourself but let's talk a true-Smooth swim type then. If these guys are looking to change their stroke rate at the same swim-speed then they will vary the amount of glide in their strokes. When swimming 'long' a smooth will be around 75 SPM. By reducing their already small glide from 0.15 to 0 seconds will increase their stroke rate from 75 SPM up to 83 SPM. That's a big increase for someone who's already swimming with a lot of rhythm in 'long' mode. It's amazing how a very small change in glide - 0.15 second is less than the blink of an eye - will make quite a large change to stroke rate which will be very noticeable to them. If we're working with a swimmer who's got a lovely smooth pool stroke this is the sort of adaptation we'd coach them through so they can perform at their best in open water where the lumpy conditions make a stroke with more rhythm essential.

> I am not a very proficient swimmer and I apologize if this question is off topic or outside the bounds of this very interesting conversation.

No Peter I think your questions were absolutely spot-on and we very much wrote this blog post with guys such as yourself in mind.

Cheers!

Adam

Unknown said...

Hi Adam,

I watched the TI videos by Terry Laughlin which are on youtube. In one of the videos he claims they have done extensive studies on the efficiency of the catch and pull. I have not seen the studies but Terry basically says what you have stated in the previous post. I'll go on their site and see if I can find any studies.

I don't remember Terri addressing the length of the glide which I guess is at issue here. I do know that according to my coach, any pause in the pull and the recovery is a no no -it should be a continuous flow. When I worked out with the masters, which was very exhausting because of my level, the coach would have us keep the spear hand/arm out until the recovery arm have completely speared. So both arms are out in front of the head. I asked the coach what is the purpose of this drill and I believe she said it was to improve body alignment and have a patient spear hand. My Ti coach disagrees with this drill.

When I watch the Mr. Smooth animation, it looks as if the spear hand/arm is in the catch phase as the other arm is recovering. In the video, it looks like the pull doesn't actually happen until the recovery hand almost enters the water. As you said in the previous post the catch is important immediately after the spear hand extension and this is what I need to work on and is perhaps why my glide maybe too long. But, its fun to glide never the less.

Peter said...

Thank you for your reply, Adam, it was most helpful and definitely makes sense from my humble experience on this point. If I increase my stroke rate only slightly, I do get the feeling that I can get sooner to my catch. It should not come as a surprise I guess, as I am catching water while moving with a slightly higher speed - not in total, just during my catch, since I am making better use of inertia. The point you made on pressing water down and delaying the catch is especially valid for me.

I guess that the graphs above show that there might be an _extended_ sweet spot for stroke length at a fixed speed, not a single number. At the far end, there is the benefit of a micro pause for muscle relaxation. At the near end, the pause is gone but inertia is maintained in a better way so that each arm movement feels slightly easier as the mechanical work needed is smaller. The kick is also a factor, of course.

I suspect that the sweet spot can be extended even more in "real" swimming as a higher stroke rate enables one to come to breath more often.