Originally Posted by Brandon Oto
If glute-ham raises are so good for improving hip extension, why aren't we all doing leg extensions to develop beastly hip flexion and powerful quads?
Back to your original question, the leg extension does nothing for hip flexion training as the hips don't really move and there is no appreciable isometric load being imposed on them. The point of the leg extension is to attempt to remove the hips from the movement.
The leg extension does build powerful quads, but only in the "leg extension" format. Not very useful IMO--same might be said of the GHR movement. Problem with the leg extension is mainly the shearing force imposed on the ACL towards the top of the movement by the thigh pad. I'm not swayed much by the Cybex pro - leg extension article
, as I personally know a guy who says he re-tore his newly repaired ACL when his PT made him do leg extensions too heavy, too soon--he heard the POP during the leg extensions!
Cressey's article on Leg Extensions.
I'm not saying the GHR is a crucial part of any programming...I don't have one, and it would be about #200 on the list of things I'd like to get next for my gym (heck, it would take up half the floor space!).
I'm just saying that comparing a GHR for the posterior chain to the Leg Extension for the anterior chain is comparing apples and oranges.
EDIT: Just saw Brandon's last post.
I think the major differences are twofold:
- Moving the body around a fixed point is generally harder and tends to come with greater benefits IMO. Hence the difficulty with which men's gymnastics is regarded.
- The GHR and the movement I describe involve two major things--first is moving the body around the knee, second is maintaining the rest of the body isometrically through space. Much harder than sitting on one's arse.