Franco (or his ghostwriter) said "a simple up and down movement is all it takes".
a lot of these champs wrote stuff like that, Mentzer wrote that merely "squeezing" Dumbbells built his forearms No.. i think unless you´ve outstanding Genetics you have to train them with a few Heavy moves & some isolation work.https://www.performforlifesf.com/blog/enhancing-forearm-muscles-effective-training-techniques
Sergio simply lifts the barbell up and down just like Franco advices.
