Best quad building exercise for people with bad knees :)

Seated Straight Leg Raise

This exercise can be performed by people who are affected by joint problems. It helps to strengthen the quadriceps muscles. Here are the steps that need to be followed:

➞ Sit on the floor, with your legs extended straight, and your hands on the sides. You could sit against a wall for support.
➞ Bend your right knee, and bring your right foot closer to your body.
➞ Tighten the thigh muscles of the left leg.
➞ Lift your left leg about 6-7 inches off the ground.
➞ Stay in this position for five seconds. Slowly lower your leg to the start position.
➞ Repeat this 10 times with each leg. You can do 3 sets of 10 repetitions.