Swim with one arm only keeping your other arm stretched out in front of you without moving.
This will allow you to focus on your extension and your ability to keep your arm still and stretched out in front of you throughout the entire stroke.
- Focus on the catch phase, underwater pull and recovery of the performing the stroke.
- Breathe on the side of the arm that is moving.
If you like, you can perform the same drill but with your stationery arm extended along your side (only in this case breathe on the side of your stationery arm!).