During the Sweeping the Hall Leg 掃堂腿 sǎo táng tuǐ, the body leg connections are explained here
body stay side, head back..
application shows why do that way
more explanations, keep the connection line
more application of it
HeJingHan BaguaQuan, Baguazhang Teaching Taipei.
See more videos at Youtube playlists
some materials could be added from HeJingHan book:
Bagua Quan Foundation Training