Throwing Javelin is a full body workout. All of your body parts interact to propel that Javelin further. Of all your body parts though, the role of your hip is fundamental.
Why?
Thrust, thrust and more thrust! As you start to throw the javelin turning on your toes creates momentum which transfers through your hip. Forcing your hip forward while holding your throwing arm back creates a bow-like tension and allows all of the force created from your toes to your hip travel through to your throwing arm. The effectiveness of this tension depends on how fast and how far forward your hip goes while you maintain your straight throwing arm. Bringing your arm through to throw from this position releasing the tension creates ‘snap’ in your throwing and the javelin will zip out!
If your hip comes through at the same time as your arm you lose out on all of this momentum and force.
If your arm comes through before your hip you will literally be throwing with your arm.
Also, the whole point of taking a run up is to create momentum. The momentum comes from your legs but if this does not transfer through your hip you may as well be taking a standing throw.
This hip thrust technique takes lots of practice to get right. What I recommend is the following:
Stand sideways to your throwing direction with arms up (throwing arm straight back, blocking arm straight towards the throwing direction). Step out with your planting foot and as it lands push off the toes of your other foot. Twist on your ankle, your knee will follow and then force that back hip through and stop. This is an extremely quick movement. Start off slowly so that you can see what is happening but as you get comfortable force it through at speed. Try to maintain your upper body position i.e. facing sideways and there is no need to have the javelin in hand. Then REPEAT, REPEAT, REPEAT!!!
If you find it difficult to keep your upper body facing sideways try the following:
Find your nearest pole or end of a wall, etc. Grab it with your throwing hand at around head height. Turn your body away from the wall until you can feel a slight stretch across your pecs/shoulder. Put your blocking arm straight out in front of you. Step out with your planting leg, rotate on your other foot and push your hip forward beyond the position of your shoulder. You should really feel the tension through your hip, up your side to your shoulder.
