Among a lot of other things, the catch-up drill can help you work on body alignment - long and straight, from the tip of the out-stretched, extended arm down through your shoulder and side all the way to your feet. Catch-up can help with breath timing and help with learning how to delay starting the pulling until the body is in a good position.
The catch-up drill is done by assuming a prone position in the water and extending your arms forward; the arms should be just a bit under the surface of the water, pointing at your destination. One arm then performs a regular freestyle pull, starting from that extension, through the catch and finish, then it recovers to an extension, pointing at your destination, back to where it started. The other arm is still, just keep it pointing forward. You should feel like you body is very long or extended, and you may feel pulses or instants of power as you pull, then pulses of gliding as one arm recovers but the other arm has not yet started pulling.
The swimming arm catches up to the arm that is still extended, pointing forward. One arm is pulling, the other is not. One arm is working, the other is waiting for its turn to work. Once the arm that was pulling completes the pull, exits the water and recovers or returns to the starting position, then it is the other arm's turn. It pulls and recovers while the other arm (the one that took the first pull) is still, waiting for its turn to pull again. Key point: you will always have one arm pointing forward toward your destination.
- Start with both arms pointing forward.
- Arm #1 swims (catch, pull, exit, recover, enter).
- Arm #2 stays out in front, pointing toward the destination.
- When arm #1 returns to the starting position, pointing forward, toward the destination, arm #2 swims.
- When arm #2 returns to the starting position, pointing forward, toward the destination, arm #1 swims.
- Each arm takes its turn swimming or maintaining the pointing forward position.
- Each hand could tag the other as it reaches the pointing position, as in one arm telling the other "OK, I have caught up to you, I am pointing forward now, your turn to swim!"
- Legs: Keep a steady, smooth, relaxed kick.
- Head: Keep your nose pointing toward the bottom of the pool, eyes looking down, the top of your head pointing in the direction of travel, a good posture from the top of your head through your neck and down your spine. When you need to breath, rotate along that posture line, eyes looking sideways as the swimming arm exits the water and recovers, on the same side as that arm. Get the eyes looking down again before that hand enters the water.
- Body: Keep a good, long posture position, top of the head through the spine, with a line drawn from the base of the spine through the top of the head pointing toward the destination. Think of that as an axis. Just before an arm starts to pull, that side of the body should already be rotated closer to the bottom of the pool. As the arm pulls, that side of the body rotates from a low/bottom of the pool position to a high/ceiling or sky position (while the other side of the body does the opposite). Visualize it - hold one hand in front of you, fingers extended, palm down. Twist the hand thumb-side up, pinkie-side down and the reverse, with the axis of the twist along a line through your middle finger.