肩甲骨がこのくらいカパッとズレるように動くと良く進むんだろうな
一番下がありがちなオッサンばちゃふらい
https://i.pinimg.com/originals/2c/23/1c/2c231c97138a45349f6114bccd5a9774.jpg
http://data.whicdn.com/images/92414009/large.jpg
http://blog.doheny.com/wp-content/uploads/2011/06/butterfly-stroke-swim-technique.jpg
http://d1s9j44aio5gjs.cloudfront.net/2014/11/woman_swimming_butterfly_technique_tips.jpg
https://img.haikudeck.com/mg/147e7791a9_1453912902523.jpg?rasterSignature=ea8be554f336212f9336825902c9849b&;theme=Clean&imageFilter=true
https://i.ytimg.com/vi/9g9maSiKMcM/maxresdefault.jpg