Friday, August 26, 2011

Hand Exiting The Water IN FRONT Of The Entry Point?

There's a common story that circulates among swimmers and coaches that legendary swimmers such as Alex Popov have such long efficient strokes that their hands exit at the back of the stroke ahead of where they entered the water at the front!

On the face of it this sounds amazing but is it true? Let's have a look at Jono Van Hazel's stroke, Olympian from the Athens games and owner of an extremely smooth efficient technique. Here's some stills of Jono's stroke taken from our Catch Masterclass DVD, he's swimming here at a steady pace of 1:10 /100m and 34 strokes per 50m.

Here's Jono's left hand entering the water:


And on the same stroke exiting at the rear:


His exit point is definitely in front of his entry point, highlighted by the red line which we've added at a fixed point relative to the lane rope. That looks very impressive but here's the twist - you might also be doing this in your own stroke.

A quick trawl through the vast Swim Smooth video archives here in Perth shows that at least half of 'normal' swimmers we've filmed enter ahead of their exit point. Here's Mike, a classic Arnie swimming around 1:55 / 100m and 48 strokes per 50m:

 

Jane, a fast developing Bambino swimming here around 2:00 / 100m and 51 strokes per 50m:

 

And Natalia, swimming here around 1:35/100m and 52 strokes per 50m:

 

All three swimmers are exiting in front of their entry points. How can this be true? And what does it mean? Let's look at Jono's full sequence of frames :


Take a close look what happens between frames 1 and 2 where the left hand is extending forwards and the right hand is finishing its stroke. The hand extends forward underwater nearly a meter before starting the stroke, driven by the propulsion of right arm and hand. Of course, the exact same thing is true for our more modest swimmers which explains how they also exit the water in front of their entry point as well.

OK, so exiting in front of entry is not such an extraordinary achievement as we were lead to believe. Jono has a fantastically efficient freestyle stroke capable of swimming 100m in sub 50 seconds but in this regard he's not outperforming our 'normal' swimmers significantly. There doesn't seem to be anything magical or mystical about his stroke length.

Jono could artificially lengthen his stroke further if he wished by introducing a glide - if he did that we'd see in frame 3 above that his left arm would still be stretched out gliding rather than catching the water. He'd certainly exit the water even further in front then. However, he does not do this as not only would it slow him down but he'd become less efficient as he has to work hard to re-accelerate himself again on the next stroke.

Here at Swim Smooth we call overly lengthening the freestyle stroke 'overgliding'. Overgliders tend to drop their elbows and wrist as they try and lengthen forwards as much as is physically possible:


Showing the palm forwards like this adds drag ("putting on the brakes") and greatly harms your catch on the water and so your propulsion. When Overgliders tidy up their strokes and remove the deadspot introduced by gliding, they generate much more propulsion and their sense of rhythm and timing returns. The result: they move closer to Jono's stroke style and swim much faster swimming for the same level of effort.

Use our Catch Masterclass DVD and/or Overglider Swim Type Guide to fix these aspects of your stroke.

Swim Smooth!

11 comments:

Anonymous said...

I've never understood the obsession with having the hand leave in front of where it entered.
The thinking seems to be that it shows how much power a verticle forearm delivers. I guess that could be true, but as you point out momentum plays an important role in that particular metric.
A more powerful kick comes into play, too.

Frank said...

Hi Paul,

Regarding the stroke timing, the common story you are talking about, is the technique of propulsion overlap. Swimspeed and propulsion measurements show, that this phenomenon is optimizing the propulsion efficiency and is limiting the maximum force needed during the propulsion.

Dutch olympic swimmer and medallist Wieger Mensonides wrote a nice articel on this topic earlyer this year. It shows differences in efficiency of a 50m sprint of VDH, swam with different overlaps... I reckon this is why Popov and VDH were outperforming the rest..;-)

link to the article, it's in dutch buth the numbers are in english too:
http://www.zwemsporttrainers.nl/index.php/artikelen/39-zwem-artikelen/186-slagfrequentie.html

Mojo365 Adrienne said...

Hmmm, thinking out loud..... If the strength of the catch by Jono achieves a DPS of 34/50m this would have to be because of his arm length right?
If a ratio was worked out with your other swimmers heights (arm lengths) would this be worked out as the same? I've assumed that the underwater catch technique & strength is what gets the distance per stroke?
So does Jono have a continuing glide whilst the leading arm is out the front to achieve more distance per stroke? Without his speed slowing down because of his strength in the pull being able to continue the speed, versus a normal swimmer who slows down if they glide because of the lack in under water strength?

Was that double dutch?
Mojo365
Adrienne (Darwin)

Frank W said...

The Dutch article looks interesting, anyone care to translate it?

JamesBoH said...

Translation (though not a very easy to read one)...
http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=auto&tl=en&u=http%3A%2F%2Fwww.zwemsporttrainers.nl%2Findex.php%2Fartikelen%2F39-zwem-artikelen%2F186-slagfrequentie.html&act=url

or just look at it in Google Chrome.

zackme said...

You explained well that swimmers with similar stroke lengths may not reach the same speed, because some overglide more than others. Ok.
But how come that the swimmers pictured, with similar (long) stroke lengths need to achieve such a wide range of strokes (34 to 50 in your sample) to swim the same 50m ? shouldn t they need a similar number of strokes?

zackme said...

You explained well that swimmers with similar stroke lengths may not reach the same speed, because some overglide more than others. Ok.
But how come that the swimmers pictured, with similar (long) stroke lengths need to achieve such a wide range of strokes (34 to 50 in your sample) to swim the same 50m ? shouldn t they need a similar number of strokes?

Adam Young said...

Hi zackme,

They have such a wide range mostly because of differences in their height and arm lengths. Also hand size plays a big part - men have much bigger hands and so generate more propulsion per stroke if all else is equal. An individual approach is so important in swimming it can't be overlooked.

The timing of the catch has a role too - some prefer to get a little quicker into their catch than others. Within a range these are all efficient.

You also see this difference in strokes per length in elite swimming, anywhere between 32 and 52 is common to see. In this light strokes per length can't be that important and it's certainly not worth compromising your swimming by chasing an artificially low number for you.

Hope that explains!

zackme said...

Thank you for the reply. In my case I believe the stroke length matters: I am 1.88m tall with rather long arms, quite large hands, thin, probably above average muscled, aged 40, and still I need 50-52 strokes for 50m. I take it that something(s) important must be improved. As I extensively watched and read about technics, and have the feeling to reproduce what I learnt rather fairly, I guess I need someone to watch me swim and tell me what I am doing wrong. By the way, your website explains better than any other ones I know, so well done and thank you. I intend to share it extensively around me.

Adam Young said...

Hi zackme, what sort of pace are you swimming?

zackme said...

50 secs for 50m.