Thanks for that information MatMT, that was the sort of information that I was really asking about originally.
Although in many countries "organisers" of events have tried to limit their liability by similar clauses only to find out that in the case of someone sustaining "personal injury", that any clause trying to delegating responsibility away from the organisers in that way doesn't stand up under the law and they have been found to be responsible even with that entry clause/condition signed by the competitor.