http://loveskate.info/upload/skate/rollerblade-twister-231.jpg
つまりこうすれば足首を痛めずサブ3.5余裕って事やな？
サンダル最強説も根強い昨今いかがお過ごしでしょうか

Mexican Tarahumara woman wins 50km race wearing only sandals
http://leaders.ng/sports-mexican-tarahumara-woman-wins-50km-race-wearing-sandals/
https://i2.wp.com/ichef.bbci.co.uk/news/660/cpsprodpb/16E0/production/_96165850_e67350e3-2385-4aea-83c5-4f6cfead0f99.jpg