I read a nice thesis about long throw technique

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I read a nice thesis about long throw technique

Postby JR » Thu Aug 09, 2007 7:36 am

This post has been edited a bit after I first posted this.

It is here: http://home.no.net/fgg/hovedoppgave.pdf Thanks to Man_Utenbart for pointing it out.

This account of the paper tries not to be exact and scientific and I haven't verified all the things I'm relating. Too lazy :-P

I don't speak Norwegian but I do speak Swedish and they were the same language until about 850 AD. I understood almost all of it. It is a final paper but nowhere was stated for what type of education. I wouldn't be surprised if this was a master's thesis.

The paper is useful for those that don't speak Norwegian too. The graphs and tables need a little background information to be understandable. If there is interest I can translate the important bits of the tables and graphs into English. Ask about a table or graph by the number so that I don't have to do the whole paper :-) You don't need to understand statistics or measurement technology and measurement manipulation to get the gist of this paper. I do understand at least most of it if not all except I've forgotten a bit about statistics. So I wouldn't want to scrutinize the methods and the theories that were used. That would get too lengthy to write. Those that have commented about my novel length posts hopefully get that I really do mean it would get loooong. And boring.

The main points under investigation were the speed at which the disc was thrown and the RPMs of the disc. The test setup assumed a planar throw that is the disc has flat angles. The test disc was a Teebird. Legwork isn't studied.

To me the paper doesn't hold any new major revelations that I'd consider to be beneficial. Off the top of my head and skimming parts of the paper I don't think that anything was said that hasn't been mentioned on this board before.

The 5 test throwers have personal distance records of 550'-600'+. One of them is the European Champion of 2003.

One surprising thing for me that the graphs showed was that the throwers tended to release the disc before the shoulders came to be in the same line as they are at normal standing position relative to the chest. Another odd thing from my perspective is that the chests pointed over 30 degrees to the left of the target at the rip. The third surprising thing was that the cameras took 240 pictures per second and still the pictures weren't perfectly sharp. There was a bit of motion blurr in the latter half of the throw. That worries me because I've wanted to eventually take a video clip of my drives with my friend's camera that can take 100 pictures per second for three seconds. That seems too slow now.

What I found most useful in this paper were the measurement results. The measurements analyzed the period of the plant foot(last step of the x step with the right leg for right hand backhand throw) and the disc ripping out of the hand. One interesting piece of data was that the time for the disc leaving the hand and the plant step hitting the ground was between 0.17 and 0.23 seconds on average of five throws selected for analysis by each thrower. The best throws weren't included in the analysis out of the ten throws that were made. The data didn't change with omission of half of the throws said the author. The best speed of the disc was a bit over 30 meters/second. The discs rotated around their center axis over 20 times per second.

Another interesting part was that it takes about 0.03 seconds for the wrist to be bent backwards from acceleration by mainly the elbow extension (my own deduction not one from the author IIRC) until the disc leaves the hand.

The conclusions of the paper were for example that one should train the muscles turning the hip. My conjecture is that because the author concluded that the torque of the hips turning higher body parts incerases distances then turning with the legs would also help a lot. This fact wasn't studied but that was what the author said that he presumes as well. Elbow chopping is also very important to be done as quickly as possible. The author found a statistically relevant positive correlation between the range of motion that the back is turned to the speed and RPM of the disc. The more the players turned their back (hips in this test) the faster and with more rotation the discs flew.

The author put a stop to a discussion that has been going on in the boards at the PDGA about height and build affecting the distance of the throws. The longer the arms the farther the disc will fly said the author and presented some data to support his conclusion.
Last edited by JR on Thu Aug 09, 2007 3:09 pm, edited 1 time in total.
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Postby black udder » Thu Aug 09, 2007 9:48 am

I only understood the pictures of the guy throwing. Everything else was gibberish.

Looks really interesting though, your summation made me wish I could read it.
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Postby JR » Thu Aug 09, 2007 3:14 pm

black udder wrote:I only understood the pictures of the guy throwing. Everything else was gibberish.

Looks really interesting though, your summation made me wish I could read it.


When I get the time I try to give an explanation of what the graphs are. I didn't explain nearly all of the tests and results in the paper in my initial post. Judging by current information I have the throwers might not have perfect form at the time of the test or maybe they had so much variance in their throws that the results were muddled. I don't believe that the author is so ignorant. He's a player and should realize which throws to disregard.

Regarding gibberish. Can you imagine how nice it is to read a scientific paper in a language I don't speak? In two days :-) Well less than that actually but divided over a two day period.
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Postby JR » Fri Aug 10, 2007 1:32 am

Tabell 3.1=table 3.1 Norwegian is easy ain't it? :-) Utover= thrower. I don't have that letter I replaced with an o in my keyboard and am too lazy to copy paste :-) Alder means age. Hoyde height of the thrower. Vekt=weight and the last column is the record throw of the player(achieevd before this test). On the second lowest row gj.snitt is short form for average. On the last row std.av. means standard deviation. For those that don't know it it is statistics and I'm not gonna detail what that is. A mathematically inclined person may have the motivation not I. It's not required to understand it for purposes of understanding what is in the graphs.

Figur 3.5 -or figure 3.5 easy like I said :-) only handles signal manipulation and measurement and doesn't tell anything that interesting with regards to torwing so ignore that.

Where things get interesting after showing principles in previous pictures is table 4.1Utg.hastighet means the speed at which the disc flies right after the rip in meters per second. Beside the speed is the standard deviation. The numbers come from five throws and are an average of those. Utg.rotasjonshast. is the rotational speed of the disc around it's center in degrees per second. Tillopshastighet means the speed at which the thrower is moving. Varighet kastfase means the time that it the throw takes in the period under scrutiny in this paper. That period is the time when the plant foot lands to the rip. I don't understand how Fotavstand or the lenght of the the step between the right leg and the left leg is arrived at measured ankle to ankle. I didn't understand/find the definitions here to be exact enough nor did I get anything like the numbers mentioned in the results. Armlengde means arm lenght. Again I don't understand how these results were arrived at.

Table 4.2 shows a statistically meaningful negative correlation between the speed at which the thrower is moivng relative to the rotational speed of the disc with a confidence level of 95 % if my memory serves me right about statistics.

Figur 4.1 is the first interesting graph of the results made with the measurement system. Zero degrees is where the target lies 90 degrees to the right of the throwers line of sight in the beginning. If the thrower raised his right arm parallel to the ground straight to his right it would point at the basket or target at this study. The degrees to the right of the sight line of the thrower (up in the graph because it is a top down view) are positive and to the left of the thrower negative. The vertical axis describes the angle in degrees of the twisting of body parts which are the hip represented by the blue line and the upper body rotation (under the pecs) represented by the red line. Horizontal axis shows the time passed. The vertical line on the left in the graph is when the right step plants and the right vertical line shows where the rip occurs. The graphs are for each thrower again named Utover 1 etc.

Figure 4.2 shows measurements of more moving parts. Only the hip and upper body rotations are absolute measurements compared to the global x axis of the measurement system. The other measurement are relative angles. Justwhat that means exactly I'm not 100 % sure of. The body parts represented by different lines (of too similar colors IMO) are in order from top down: Right shoulder extension, right shoulder turning back away from the target, shoulder rotation, elbow extension, elbow what? and the extension of the hand from wrist down in the end of the throw increasing the spin on the disc tremendously(the coveted big snap's end result resulting in the disc leaving the hand faster and fading later thus retaining altitude longer thus increasing the time and speed the disc stays in the air giving big D).

Table 4.3 shows hip rotation in degrees. Minimumsvinkel shows the amount of reach back from the hip in degrees with standard deviations beside the degree number. Slippunktsvinkel means the rotation of the hip at the time of the rip. Bev. utslag shows the amount of total rotation that the hip achieved.

Table 4.4 shows upper body rotation(from under the pecs), 4.5 shows horizontal shoulder movements and 4.6 elbow motions. 4.7 shows how the wrist moves.

Table 4.8 shows that there is a statistically meaningful positive correltaion between the amount of degrees that the hips turn relative to the speed and RPMs of the disc with a confidence level of 95 %.

Figure 4.3 shows the amount of degrees that different parts turn per second. The parts are in desceding order: Hip rotation, upper body rotation, right shoulder extension, elbow extension, wrist turning with negative numbers meaning turning back and positive number meaning going forward compared to the direction of movement of the player.

Figure 4.4 shows also the dis relative to the hand.

Table 4.11 shows that there is a positive correlation yada yada between the maximum turning speed of the wrist forward and the RPM that the disc achieevs. So remember to chop the elboe quickly. And do remember that correlation doesn't automatically mean causality :-) More later when you've had the time to digest this and if there is demand. Please say if you'd like me to continue. I wouldn't want to do work that has no benefit to anyone.
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Postby JerryS » Fri Aug 10, 2007 2:55 pm

This is great info, please continue.

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Postby JR » Sat Aug 11, 2007 6:00 am

The tables and figures follow the same logic as in previous explanations so I won't give details of the previously mentioned information and presentation details here.

Figure 4.5 shows the speed of the estimated center of the measured parts of the body. The curves are in descending order disc, hand, wrist, elbow, shoulder and hip. I presume that the marker is the right hip marker. Table 4.12 shows the maximum speed of the measured parts. Table 4.13 shows when the maximum speed for those parts happen in percentage of the time spent between the right foot planting at 0 % and the disc ripping at 100 %.

Table 4.14 shows the maximum speed of measured parts moving towards the target. The body parts are from left to right back, shoulder, elbow, wrist, hand and the center of the disc. Table 4.15 shows when the maximum speed occurs.

See if you remember the names of the body parts in figure 4.6 :-)

Figure 4.7 is interesting. It shows the photos taken by the measurement system. I think without calculating that it is indeed possible that the pictures are consecutive and each picture is shown. You decide :-) Each showed picture of the position of the markers are connected by lines. The pictures start from the plant and end three pictures after the disc has ripped. The higher picture per thrower shows the throws from the side and the lower shows the throw from above. The markers are in descending order left shoulder, right shoulder, elbow, wrist, hand and the disc.

Figure 5.1 shows what the author said before that in the text that the small number of throwers influence correlation calculations significantly and therefore one shouldn't make far reaching conclusions about the correlation figures. A test with more throwers is needed for valid numbers. The figure has the speed of the disc on the y axis and the maximum rotaional speed of the hip.

Of note is that I've translated the word bekken all the time as hip even though it means back. My assumption has been that the way to make the marker at the back turn is by rotating the hips. Right or false so take this into account. The reason I deduced that the back is actually the hip in these occasions is that in some measurements there are back and upper body markers that measure turning and the turning happens at the hip for the back marker and below the pecs for the upper body. Shoulder markers are mentioned sequentially next after the upper body marker so I hope my assumptions are correct.

Figure 5.4 shows the position of the hand at one point in time before the rip in a. In b speed components for different body parts are shown as directions of the motion of the body part. C shows the resulting speed components together from shoulder to the wrist with the black dashed vector and the center of the disc with the red dashed vector. The amounts of force are not shown in real amounts.

Figure 5.5 isn't interesting IMO and only shows the same thing as 5.4 with little more detail.

There's several pages worth of discussion and conclusions in the end of the paper but much of it can be deduced just by looking at the measurements with thought. There was nothing revelational in there anyway.
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Postby JR » Sat Aug 11, 2007 9:59 am

Oh boy did I make a nasty mistake in my previous thinking and in the posts. Language troubles... Adjust your thinking accordingly.

Bakken is not back but behind. The actual location of the markers seen from the picture in the paper is just under the pants of the guy. These markers are visible both from hehind and front.
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