The angle of falling is measured from ball of foot to hip, at the end of the fall when the swing foot passes the support leg. There ideally shouldn’t be any angle at mid-stance.
This is a so called 'new material' record. When all athletes use these new kind of springed shoes, then we're talking, so do not talk about running technique here ok. World records are falling like rain these days. Look at Kelvin Kiptum's running technique with his awful swinging from left to right
