Check out the start of the men’s 1500 at worlds this year:
https://youtu.be/uga45jtFAbo?t=32
Every single runner immediately picks up their leading foot. Engels seems to do a bit of a side step and generates a lot of power off this. Jakob instead basically steps backwards and then starts running.
Kipchoge’s start at INEOS last weekend looked similarly awkward.
What is ‘optimal?’ Are you supposed to keep the lead foot planted and “roll” your weight over it?