[quote]maz20 wrote:
Is there such a thing as a lying “leg extension” machine?[/quote]
Not that I’ve ever seen, nope. Some kind of band setup would be the closest to it. But…
The quads weren’t meant to be isolated through that extreme range of motion. That is, the knee isn’t structurally designed to support the stress induced by that much ROM.
“Regular” leg extensions have a high amount of knee stress at the bottom position, further increasing that ROM would increase the knee stress without significantly increasing the muscular stress. The knee joint needs the support of the hams, glutes, and quads working in coordination.
Stick with “standard” leg extensions, deep front squats, the hack machine, sissy squats, or maybe those somersault squats posted above.
Those somersault squats, BTW, sort of remind me of a Smith machine Pierre Roy Squat (used for different purposes though). The Roy squat is less continuous tension and more hamstrings.