The leg extension exercise is performed to target the leg and quadriceps muscles. Beginners may take the help of a quad machine or even free weights to do this exercise in case the machine is not available. This exercise also works the thigh muscles besides working on legs. It is recommended that you avoid the leg extension exercise if you have knee problems.
Before grabbing the weight machines, workout for 10—15 minutes to warm-up your body by using a treadmill or by stretching. It will help your body to loosen, providing required flexibility.