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It's important to warm up properly before a good workout.

A good warm-up includes enough swimming, kicking and pulling so that you have stretched your muscles and gotten your heart rate up to an exercise level.

Think of it like starting a car engine on a cold morning -- for maximum performance, you need to warm up the engine so the oil is circulating to all of the engine's parts and they are ready to work.

The heart is your engine that needs to warm up enough to circulate blood to all of the working muscles so they are ready to work.