What a biomechanics should know before work on javelin throw!

by Carlos M D Cunha

1- Blocking from a high C. Mass position will provoke much stress to L5…L3 because the energy go down an most of if stay’s in the thrower.
2- A short angle at shoulder will stress too much that join when it have to rotate at fast speed.
3- Besides the release angle, high and speed the application of the Torricelli Equation shows the importance of delivery length witch can be measure starting where right hand is at the block moment until the position javelin leave the hand above left foot contact position. Also the direction of this length should be align to the deliver angle. This shows the importance of shoulders positioning before the block.

4- The time in between right and left foot only matters if point 3 is maximized.

5- The muscles have a timing to be effectively activated so to create a effective block all the left side should act as once and that includes foot. Landing with the foot by the heel creates a delay on the effectiveness of block that can no longer support the kinetic energy of the run-up so it should land all foot at once. This will let time to all muscles from left side back and lower limb activate and support one each other.
6- Lastly you should been almost full stretch to use the stretch-reflex. Because at the time the block take place the right hip is launch forward and every single muscle from hip to right hand will stretch to maximum creating the “PULL” at the javelin. As all should know at that time what is not fully stretched and relaxed will slow-down the entire system because they will be stretched by the strengths involved on that time by the side block.

7- (Since only a few uses the “warp” this point is for those). Bringing the hip rotation to the block will booster the block because the mechanic issue of changing the center of rotational momentum will have a greater effect on stretching the right side because the rotational momentum is twice or even 3 times allowing the hip to advance those 5-10 cm in a shorter time provoking a faster groin pull.
Note all this speech is made for a right hand thrower.
By studding engineering we learn that errors do propagate and also any effect had one cause. Using engineering to build bio-mechanic models we can predict and avoid injuries, we can save time correcting the source and not the effect of the error. We can also figure what limitations are pushing you to the error or to the low performance. Bio-engineer would help you to solve difficulties, lack of performance, build strength where you have weakness. Design exercises and machines. The “working angle” of your levers and muscles through adaptation is so important like intensity and volume on workouts like rest and recover, like diet for a good balanced training. Amplitude is a must when we look for performance because of power application.

Example: Some will experience difficulties to plant for block. It could be because of anxiety at upper body and lack of relaxing waist area or could be a parasite effect of shoulders back movement during penultimate (transition) which creates the front foot to rise in the air taking more time to land or even a misconception of back leg and hip move direction. Bio-engineer will solve the parasite effect by defining exercises to get your shoulders back before the transition step and not during the step. For the anxiety we try to keep the athlete on a general state of relax and focus only on the active sequence to gather the technique correctly. For misconception we create bio-mechanic model with levers, joins, forces and application points over time to rebuild the model find what go first to keep on a good sequence tracks. We follow the logic.

Barbora Spotakova in the javelin at the IAAF Diamond League meeting in Eugene

Bio-mechanic now shows what you are doing and what you should do but not showing how or why you aren’t doing the right way. The coach will always must find what we can do and build the “way” to do it and also posing the “question: ”And if the athlete can’t do it all?”. ”What he can do to keep in the tracks?”. “From the sequence parts he can do which are the ones that give him the best performance keeping in mind that he will overcome those lacks or weakness?” An example is the use of warp or not. Everyone knows warping can add more 4-6m (because gets a faster stretch reflex) but is a hell difficult to do at high speed and sure difficult to manager rotation with the rectilinear run-up direction, so many big throwers +1.90 prefer use his height advantage and not try a more coordination on a rectilinear + rotational technique. It is all about read how you use power, amplitude and coordination that make the coach a good coach and how he overcome those lacks keeping athlete’s integrity!

Note all this speech is made for a right hand thrower.


Carlos M D Cunha “- I forced myself to relax! It is not enough to be relaxed you have to force yourself!” That is a lesson I did learn! For a strong man throwing 800 gm is so difficult to use all your strength that relaxing is a must to stretch and get amplitude… use the levers on powerful zone and with all the range you can get.


Coach is a master related with adaptation. He knows how the brain acquire movements, how coordination works, how muscles work and how are stimulate, how they develop, relation between muscles and tendons, what ligaments are for how bones and joins interact, myostatic stretch reflex and intrinsic tissues resistance. Knows basic sport diet. Knows stretching for different proposes. And knows what is stress, frustration, ethic and a lot of things but one thing he must know, his own limitations and where to find help.

Implications / Height matters! 9 cm in height increase, from 177cm to 186cm could mean 5-6% increase in body height to the result. Following this calculation a 2m height thrower may result in an over 100 m throw. The calculation of a javelin throw follows a far more variable containing equitation than adding percentages of body height: technique, specific strength, flexibility, speed, dynamics of throw, alignments, etc.

Using Torricelli equation to understand javelin technique. How training changes fit in Torricelli equation (taking also consideration flexibility, mobility and speed)
Example: Reduce of velocity run-up to rise the delivery length and what it could mean in distance from 88,5 to 96,6. Run-up 7=>6 m/s, keep the same strength applied 243,1 Newton and rise delivery length from 1,4 m to 1,7 m.

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