Javelin throw is a competition that dispenses the stadium. Do you need to train and only there? No. If we have a forest, park, beaches -let's use of these sites. I am a supporter of varied training in different places. Training speed, jumping can do almost anywhere where there is grass and level ground. Training on the beach further strengthens the ankles. We are working on stabilization and motor coordination. The forest is a great place to do cross-country forces. In regular grass can improve technique elements of projective thinking, of course, to other people. Maybe the side it will look weird but you should not be interested. Focus on getting the job done training and have a lot of satisfaction from that.