The seated leg extension isolates the...
sagittal plane
The rectus femoris becomes active in a leg extension because one of the actions of the rectus femoris is hip extension, as well as knee extension. The rectus femoris crosses both the hip and knee on the anterior side of the body. When the leg is extended it is one of the primary movers, whether it be straight leg extension, in which case it is the rectus femoris, illium and psoas muscles. In knee extension the rectus femoris works in conjunction with the other 3 quadriceps. However, in the case of a seated leg extension the rectus femois is less active, due to it already being shortened for the hip extension.
flexion
Leg extension exercises focus on quadriceps.
extension
Gluteus maximus
No
I like to do hamstring curls to work the lower part of my hamstrings which dead lifts don't really touch. But my gym is gay and only has those seated hamstring curl machines where you actually SIT on your hamstrings, the most stupid thing i have ever seen, yes sit on the muscle you are trying to work. Anyway I can do improvised curls on the leg extension machine, if I face the seat.
leg press leg extension running and sprints
Extension of the leg at the knee
The vastus medialis is involved in leg extensions.
Treadmill, elliptical, Lat Pulldowns, Low Row, Step up motion, Smith machince, Inclince press, Decline press, Calf Raise Machine, Shoulder Fly Machine, Shoulder Press Machine, Seated Dips, Hip Adduction, Hip Abduction, Leg Curl, Leg Extension, Leg Press Machine, Pec Deck,