Hip Mobility and rotation of your hips is essential to sprinting.
Genetics play a role certainly as we are born with certain traits and attachment points of the muscles esp. glutes and hamstrings …,
" Would you like to gain a free meter in the 100meters"…
" The rotation of the hip towards the center line in the full upright position allows the hip to turn a total of 3 inches ( forward and backward) producing a stride length gain of 1.5 inches over a hip locked position with no additional effort. A top sprinter takes about 29 steps in the full upright position in the 100m where full rotation can occur. ( 29.1.5" = 45.5" or 1.1m. ( Note : this blurb is at the bottom of one of the graghs created with Charlie’s ideas and are based on actual silhouettes of World Class sprinters in action).
( I am in the process of locating the product where this slide and illustration can be viewed. In the interim I will scan this and post it when I make time 