Question about Range of Motion (ROM)

[YuanHao]

Hello coach how are you doing today?

I'm going to be brief.

In this video you said:

"We want a vertical forearm because that involves a greater range of motion and therefore trains more muscle mass."

And in this thread you said:

"ATG does not work less muscle mass; it works the same muscle mass with a longer ROM but lower weight. My point is that the amount of weight lifted must ultimately be a consideration, and as long as all the muscle mass is getting worked through it's functional ROM, you should not go deeper at the expense of lifting less weight."

Now, I perfectly understand the reason why it's not necessary to do ATG (ass to grass) squats. I never go ATG in real life or at any sport. It's not a very common or functional position/movement.

BUT I also thought that longer ROM = more muscle mass trained.

Those two statements seem to contradict each other, unless I'm missing something.

[Mark Rippetoe]

They could be construed to do so. Why might I regard this as a specious argument? It's right there in the quotes you pulled.