Imagine swimming across lac St-Jean in Quebec, Canada and another swimmer starts to push the pace.

With over 10 km to go, you are tired but know that you have to start giving it your all. When do you continue to feed? Do you keep your own feeding schedule or do you modify your schedule to match your competitor? If they slow down, do you? If they speed up, do you? Do you pick up your kick or your arm tempo? Do you keep the same navigational line as your competitor or do you take a chance at a different line?

These are the different types of questions and issues that go through the minds of the professional marathon swimmers all the time on the FINA Open Water Swimming Grand Prix circuit. Mallory Mead and Lexie Kelly are shown above in the Traversée internationale du lac St-Jean.

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