Abs hypertrophy question

[Kiceres]

Hi all!

In "abs hypertrophy" workout, are we supposed to lift our legs 90° during leg raises, or about 50-60°?

I tend to lift my lower back as well, sort of like a kick. Is this wrong/useless?

TIA

 

[Fremen]

In "abs hypertrophy" workout, are we supposed to lift our legs 90° during leg raises, or about 50-60°?

The higher you raise your legs, the more it works an upper part of the abs

I tend to lift my lower back as well, sort of like a kick. Is this wrong/useless?

Your back must always remain completely flat on the ground otherwise you will hurt yourself