This page is still in preparation so it will change quite rapidly.
Throwing the javelin is quite simply about speed of delivery. All other things being equal, the distance it travels is proportional to the square of the velocity at which it leaves the athlete's hand. In other words, for a thrower to increase from 50m. to a rather more eye-catching 100m. requires only around 40% more velocity. Needless to say, it isn't easy to acquire. However moving from 50m to 60m. requires only 10% more velocity.
Javelin training is therefore about increasing the velocity of the arm at the point of delivery. We can immediately see that bulk muscle is not terribly helpful because Force = Mass x Acceleration so if the mass of the limb increases proportionate with the force which it can apply, the acceleration of the arm stays the same and so does the terminal velocity. Similarly, if the javelin thrower has a long pull on the javelin, he or she has a greater chance of continuing the acceleration for a longer period leading to a faster final delivery. So its all about long, rapidly acclerating movements of limbs not weighed down by bulk muscle.
As well as the usual running and jumping exercises, the javelin thrower can progress well with surprisingly crude training equipment. For example, tying together three inner tubes and attaching them to something strong allows the thrower to practice long rangy movements with increasing tension over the full throwing range.
Medicine balls are a must. They should not be too heavy with a range of perhaps 1kg - 3kg. Repetitive throwing against walls with various throwing techniques, (both hands over head), both hands rotating over right hip for a right-handed thrower, single handed throwing of the lighter balls as well as sitting throws are all very useful.
Throwing balls with weights comparable to a javelin are easily obtained quite cheaply and are excellent for warming up.
Good shoes with heel spikes are also a must. Modern tartan run-ups can become very slippy in the wet and shoes with no spikes or spikes in the sole only are simply dangerous.
Javelin throwing puts unusual stresses on the body. If the rhythm of the throw is slightly wrong, this can transfer additional stress to the body. One of the most common areas this occurs in is around the lower part of the elbow. A good strength training exercise apart from such things as pull-overs is to do wrist rolling. In its simplest form, just attach a weight on a string and wrap it around it metal bar. Then roll the weight up and down. Using an asymmetric piece of scaffolding or something is even better as the stresses are then variable. This will strengthen the arms around the elbow area.