I'm not sure if this used to be a bug, but the line used to mean that for people hp 31+, if they had 50 stamina, do nothing, if they less stamina make them advance faster.

Stamina is supposed to make you gain hps faster, no?

But taking this to numbers:
HP 31:
-1550 -((50+50)*50)=-6550
yeah, okay, I messed this one up bigtime...