Butterfly using one arm only
Sometimes your technique can suffer after swimming just a few strokes of butterfly because of the exertion involved. Performing this drill regularly will allow you to improve your technique and swim properly even when you are tired. Begin by swimming with your legs only, keeping your arms extended out in front. Swim butterfly with one arm only. Focus on the catch phase, underwater pull (your hand should emerge from the water as it passes your thigh) and arm recovery. Remember to focus on all the other parts of your swim stroke: try and make your leg kick rapid and move your arms and legs as smoothly as possible.