With your high jump example, you also have to take into account changes in the rules and equipment available for the event. The reason that the straddle jump was used was because they used to land into a sand pit, not a foam cushion. If you tried to do the fosbury in those conditions you would break your neck.
And swimming - well technology has played a big part there.
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Behold, I see my father and mother.
I see all my dead relatives seated.
I see my master seated in Paradise and Paradise is beautiful and green; with him are men and boy servants.
He calls me. Take me to him.