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Patterns of temporal change in speeds for (a) elite race winners since 1997, (b) elite race finishers since 1997, (c) all race winners since 1997, (d) all race finishers since 1997. Circles, squares and triangles represent average speed (relative to 1997 mean) predicted from model 2 at 6, 10 and 17 furlongs, respectively (bars indicate ±1 s.e.).
