An Anonymous Reader Writes:
One armed butterfly is a swimming drill that helps your butterfly stroke because it is easier and isn’t as tiring as the full stroke, so you can do it for a longer time.
To practice this drill, you just do the butterfly technique using one arm. Your other arm is either kept at your side or extended overhead. You could, for example, do 25 meters of the drill using your left arm then 25 meters using your right arm.
When you do regular butterfly it’s hard to do it for anything but a short time so you end up not being able to practice as much. If you do it with just one arm it is easier and you can do it without getting tired. Also, you can get the stroke perfect.
Once you think you get how to do this drill you can try doing a few laps of proper butterfly stroke.
This is indeed a nice drill. We practiced it regularly when I took swimming lessons a few years ago. To practice this drill we used short swim fins.
This drill allows you to get the feel of the butterfly stroke, and especially the movements of the body dolphin. It also lets you practice the correct timing of the arm stroke without getting tired quickly, as described above by our anonymous reader.
Thanks for posting this!