Counting reps in hollow body rocks

Apologies in advance if this has been asked previously; I searched but did not find...

 

When doing the various hollow body rocks in the FL progression, how are you supposed to count? Is it one count every time the legs dip towards the ground, or is it one count when the legs dip AND one count when the head dips? I have been going with the former, but reading the guidelines makes me wonder...

 

 

One complete rock is forward and then back. So if you start with your legs down and your back up, you would count up by one each time your legs dip towards ground.

 

Or more succinctly, the harder one 

Thank goodness I have been doing these correctly .