What muscles do leg extension work?

A leg extension exercise tests how well someone is able to work against the resistance of the leg extension machine. In the process it works four muscles in the trainer's upper thighs that are called quadriceps. The muscles that make up the quadriceps are called: Rectus Femoris, Vastus Intermedius, Vastus Lateralis and finally, Vastus Medialis. This machine is great for anyone that wants to train for any type of race or just training to be better fit.