There are many kinds of run up that are just as good, as long as you can handle the speed. I started learning the javelin at age 55 and went from 22 to 35 meters as a W55. My run up exists of 6 simple steps, 6 steps with the spear back and then the the last 'soft' step (that is a hard block with left and a soft downward action of right). It went better when I started to count the steps in my head. The first six are normal running, the second with a lowered c.g. Etcetera etcetera, this most likely is not an answer but I like the javelin, heigh! Do you know the javelin discussion forum? You maybe can make a video and ask them for help, they are very willing to help.
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