Whereas in the previous front crawl drill, Under Switch, the focus was on the synergy between arm stroke movements and body roll, in Zipper Switch the focus is on achieving a compact and efficient arm recovery:
Achieving a compact recovery allows you to decrease drag and save energy, as explained in Swimming Mistakes: Wide Arm Recovery.
Drill Instructions
This drill starts exactly like Under Switch:
You are floating half on your back and half on your side.
You use a supple flutter kick for moving forward.
TopSync
Your top arm rests on your side, your bottom arm is extended forward under water.
Your face is turned toward the ceiling.
Once you are balanced, rotate your head in a downward position:
Your body rolls into a position where it is at a 90° angle with the water surface.
Your face is turned toward the bottom.
Your arms have kept their respective positions.
Take a few moments to rebalance, then start the recovery forward of your top arm:
Sweep your hand forward past your hip, rib cage and shoulder, as if pulling up a zipper.
Lead the recovery with a high elbow and let your forearm dangle down from the elbow.
Let your hand drag in the water. The pressure of the water against the hand will ensure that you lead the recovery with your elbow.
Enter the water with your hand once it has moved past your head.
Extend your arm forward under water into the overhead position.
As the recovering arm enters the water, the other arm starts to sweep backward and to push against the water for propulsion.
Simultaneously roll on your other side and continue the arm movements until one arm is completely extended in the overhead position and the other arm rests on your top side.
You are now back into the initial position but floating on the other side. Take a few moments to catch your breath, then start the cycle again toward the other side, and so on.
BottomSync
Swimming Drill Tips
Practice the drill until your recovery feels compact and efficient and you can maintain your balance throughout the whole cycle.
Once you have mastered simple switches you can practice double and triple switches like you did in Under Switch. Multiple switches teach you the rhythm you will use while swimming the full crawl stroke.
Previous Drill – Under Switch
Next Drill – Over Switch