Fu-Kwun Hang, thank you for creating the animated gif.
I realise now that the static images I provided were not taken at equal time intervals, hence the rather jerky animation. It's a pity - my athlete would really benefit from a longer, richer sequence that we can slow down and study (which would probably require a hundred or more images in the sequence). The videos I find on YouTube tend to be very grainy and shot at too few 'frames per second' to really see the detail, especially at the moment of the strike. Does anyone out there know of a good quality slow-motion sequence of a world-class javelin thrower?