The cross connection ensures the same thing in water that you do on land. If a swimmer has correct timing between their arms/legs in the pool—they will have a more efficient stroke
When a swimmer is swimming Freestyle, making sure they have the correct connection (or timing) between the arms and legs is super important. Just like when we walk or run, we have a certain gait—well, it’s the same for when we swim.
It’s important to note that when you are walking and running, you have a cross-connection happening within your body that allows your body to take a LONGER step (or a further stride) than without this cross-connection. To avoid going into further detail what is good about this cross-connection from an anatomical and physiological connection—just know you fire more muscle fibers within a more correct firing pattern than without it.