Top throwers wanted!


Almost by accident, I’ve managed to get access to a state-of-the-art lab at the Institute of Motion Analysis & Research at the University of Dundee, and the help of the experienced technicians who run it, for something like 10 full days this summer. This is going to be fun…

Frisbee

We’re going to get some data on throwing techniques for a whole bunch of people, and we’d really love to have some top throwers – male and female – come and join us. We’re looking at variations in technique and the effect these have on the ability to generate power and spin. Obviously we’d love to study some people who can throw it 80 yards – but we’d also be very interested in people who can throw it 60-70 yards despite not being able to bench-press a boiled egg. People who throw well with particularly short or long arms. People who have a reputation for throwing particularly well in wind. People who do something a bit weird but still get results.

The brief version – we’re going to get 40-50 people into a laboratory over the coming months, where we’ll do motion-capture of a bunch of throws, and then we’ll look for correlations between the way people do it and the results they get. Hopefully, we’ll get some really top throwers, and some intermediate ones, and we’ll look at the differences. Nothing quite like this has been done before, to my knowledge (shout if you know of anything!).

One paper (Hummel thesis, chapter 4) studied one thrower in similar detail, but was unable to compare the technique of that one player with others, and hence does not offer a more rounded view of where power is generated or what effect different styles have or any of those things. In short, we stand to learn an awful lot, and then we’ll write it all up as an academic paper – and some blog posts too!

Here’s the geeky (but to me, vastly interesting) version. Skip to the end now if detail isn’t your thing.

The thrower and the disc are dotted with about 30 reflective markers, on all the joints (wrists, knees, shoulders etc.) and other places of interest. These markers are then picked up in real time by around 15 cameras working at 400 frames/second. For every marker, for every frame, we get the position (accurate to around half a millimetre in 3 dimensions), and also the velocity and the acceleration. The distance between any two markers, or the angle between two or more, can also be automatically calculated.

[To give you a clue about the accuracy of this stuff – looking at the marker in the dead centre of the disc, our test-runs pick up a tiny repeated oscillation in the z-axis (up and down) after release. As far as we can tell, this seems to be caused by the flexing of the disc – it deforms slightly when you pull on it, and after you let go it flexes back and forth for a while… If that isn’t cool, then you’re reading the wrong blog.]

We get information such as how fast or how many degrees the wrist snaps, how many degrees the shoulders turn, the amount of bend in the elbow at release, how much the hand is accelerating at release; pretty much anything we want, at 400 frames/second. We also get ‘result’ information – the velocity and spin of the disc after release, and (across a number of trials) how consistently you throw it in the same direction. We’ll also measure things like the thrower’s lever-length and basic strength, in case we need to adjust for these factors.

Then we look for qualitative patterns and for quantitative correlations between all the things we’ve measured and the results we get. How much of the velocity of the disc comes from the arm-speed, and how much from snapping the wrist? Do you get more spin by consciously flicking the wrist, or by keeping the wrist fairly stiff and letting the disc flick off the fingers? Does whipping a forehand from the elbow result in more spin or power than a less whippy motion? You might think you have an answer to all these already – but wouldn’t it be great to know?

Clearly, we need to be careful with our stats. If we look at a lot of things that we think might influence results, then there’s a goodish chance that some of them will correlate just by chance. Perhaps more research will be needed on the things that appear to be flagged up by this research. We don’t know yet how noisy our results will be. But it’ll be fun finding out – and we may just come close to answering some interesting questions of technique.

And for those who are reading this and thinking we could never measure anything game-like – people’s ability to vary their throws, their accuracy at hitting a moving target, their decision making – well, of course you’re right. All we plan to do is to ask people to throw a bunch of flattish backhands and forehands, at the comfortable limit of their power (so not over-throwing) and see what sort of biomechanics lead to what result. It won’t define what makes a good thrower. But it just might give us some clues about how we create spin or power or consistency that will help us to coach or to learn.

And since we’re already in the lab, and the time-consuming bit is to cover the body in markers, we’ll also get a ton of other data which we might not have chance to fully analyse any time soon. Recording extra throws is extremely quick and painless. So we’ll get people to over-throw the disc, to try too hard, and see what if anything is different when it goes wrong. We’ll maybe get people to throw deliberately with extra I/O or skip curve and see precisely how they achieve that. If someone really wants a stick-man video of themselves throwing a scoober, we can do that too. And if someone comments below with a good idea, we’ll add that in.

So – if you’re going to be in Scotland any time between now and September, get in touch and get tested. It’s going to be awesome.

Fill in the form below if you want to join in, or drop me a message through the facebook page if you want to recommend a particular player I should get in touch with, or for any other queries.

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24 Responses to Top throwers wanted!

  1. Felix says:

    If the motion-capture could be saved and imprinted onto players in a future ultimate computer game, that would be ace.

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  2. Peps says:

    Love the idea guys, I’m shocked this hasn’t been done in the states in some detail already!! As someone with a sports biomechanics background and a fair bit of motion capture experience (PhD at Loughborough with England Cricket looking at a very similar project using the same tech – in fact you could probably replace ultimate with cricket in your article and I could submit it 😛 ) it is really interesting!! Would love to spend a bit of time at T1 chatting about it and might even be able to add something, I’m playing for JR but you might recognise me as having been Haze captain this year just gone… Will try to come over to find Glasgow but if you see any pink shorts wandering around nearby looking lost just ask for Peps! Until Saturday…

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  3. the_penfool says:

    Maybe get some complete beginners, get them to throw on the first day, then make them practise like a bitch with a coach for 2 weeks and get them to come back and see how their throwing has changed….

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    • Good plan – you got access to 20 beginners with 2 weeks to spare? 😉

      More seriously, it’d be fun to do something like that, but seems to me that’s likely to be a funding issue – complete beginners who are sufficiently obsessed with frisbee to volunteer for this are pretty thin on the ground… we’d need to pay ’em. We can get fairly similar results by comparing beginner with experienced rather than the same person at two different times. And someone’s done something like that – http://www.ncbi.nlm.nih.gov/pubmed/18972880 (thanks to Alan Carter for pointing me to that paper!)

      Like

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  5. Alex says:

    It may be outside the scope of what you can do with the markers and capture, but it would be interesting to study the manner of grip as it relates to the different throwing motions and resultant throws. Most people accept the general principal that the “split finger” grip does not generate quite as much spin/distance as a “power” grip, but there is also the placement and the angle of the fingers to be considered. With your fingers placed on the rim of the disc, your wrist snap is more of a back to front motion, or involves a twist of the wrist from vertical to flat. With the fingers flat on the bottom of the disc, the wrist motion is side-to-side, and the hand remains flat through release. Is one better than the other? The spare fingers can have some effects as well. Do people throw better while curling them in towards the palm, or with them extended against the outside of the rim (vulcan style).

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    • Would be really interesting to measure all that stuff in detail – but it might need to be another project. The real-time pressure sensors we have access to would be too bulky to fit to the inside of a disc without distorting other data – and probably too delicate to throw around! We could make a note of whether someone uses one particular grip or another, but we couldn’t get access to the real detailed info of what they do with that grip – which I suspect may actually be more important than where they think they put their fingers.

      But we will certainly be looking at whether the wrist is moving back to front or side to side – and we’ll take a note of what grip people use and see whether anything interesting shows up. Thanks!

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  7. Martin says:

    Hello,
    I just finished my bachelor studies at the Slovak Technical University of Technology in Bratislava .. and guess..my final thesis was right on this issue. Of course I did not have the high technology like you. all measurements were done in “home conditions”. The camera was not special (to 2 days before state tests I found out about a friend who has a high-speed cameras). At work, I focus only on hand. Evaluation of data I was doing in the program Matlab. In my work was a lot of weaknesses. But I want to work on it in my next master studies!

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  8. Rob Barchard says:

    I know when I’m teaching consistent flat forehands I talk a lot about external rotation and cue lifting the medial epicondial process. It might useful to use markers on both the lateral and medial aspects of the elbow and wrist to get more detail in the rotational aspects of the limbs while going through the throwing motion.
    Different throwers use different body mechanics to change IO / OI aspects of the disc. Looking into what aspects allow for, for example, consistent IO forehands would be very cool. Should the angles be generated more from shoulder adduction, elbow extension, wrist supination / external arm rotation ?
    Very excited to see what results you can produce. Is there a way I can get on a email list for when updates / results / cool videos become available?

    Like

    • Hi Rob,
      We should get pretty good detail on the rotation of the arm and wrist – I can’t recall off the top of my head where all the markers are placed, but the technicians in the lab are pretty experienced and using a fairly standard set-up which should capture all the motions. There’s definitely more than one on each of the elbow and wrist.
      Any news we get will be published here, and I suspect Charlie from Ultiworld will pick it up too – he was pretty excited about this project…

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  9. Guest says:

    It will certainly be interesting to get a detailed look at the mechanics of the throwing arm. I would be most interested in the throwers use of core and hip muscles in generating torque.

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  12. chodiepalmer says:

    Hey! I was wondering if the results of this have been published yet? I’m doing research for a potential study of my own and would really like to have a look at what this project found out!

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    • They haven’t I’m afraid – but I did hear back for the lab just yesterday that they’ve extracted a bunch of data finally. I thought they’d forgotten! But things are apparently moving. Basically, there is an unreal amount of work to tag all the various markers for each throw; the techs have been very busy; and I can’t do it as it can only be done on their software in the lab. But now we have something resembling hope again!

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      • Anonymous says:

        Hey there! Just another bump. The work you’ve done for this looks so interesting and I would love to see the outcomes!

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      • Adam says:

        Bump again. Also I just got a job at a motion capture company and will have access to motion capture software. It’s not Vicon like you show in your picture, but perhaps it’s possible for me to work with the data to give this project some new life?

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        • I can try again – haven’t heard from them in absolutely ages! But it’s very doubtful that they could send the data elsewhere – it’s a medical facility, so their data protection stuff is watertight and the release forms signed by participants only allow that one lab to access the data.

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