I've read that the most efficient way to run a race is a negative split. Does this only apply to longer distances, or is this still effective for a 5k? How much faster should the second half be than the first? : running

I've read that the most efficient way to run a race is a negative split. Does this only apply to longer distances, or is this still effective for a 5k? How much faster should the second half be than the first? : running:

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