That's similar to what the open water long distance butterfly competitors do. Believe it or not, they do 5km butterfly "races" in open water, so they must maximize momentum over time to conserve energy. There's no law saying "thou shalt do full intensity Butterfly strokes". You do what you enjoy! I do full intensity for short distances and a slower graceful Butterfly just for endurance.
Hi, thanks for drop by here. I google translate your comment. And my answer is you can make it butterfly by step by step drills with fins(if its hard for you) even you are a heavy weights Your comment: Digioenㆍ2hours ago (edited) What would it mean to go 5 kilos like that?