Hi, I'm Sarah Huggins with LIVESTRONG.COM, and I'm going to show you some exercises that'll isolate your quadriceps and help strengthen your knee. Isolate Quads to Strengthen the Knee. The first one that you're going to want to do is called the isometric side tensor. You're going to sit on the floor on a mat. Squeeze and hold your thighs for 10 to 15 seconds and then release. Squeeze and hold and then release. Repeat that 8 to 12 times. Lying Leg Lift. The next exercise is the lying leg lift. Lay back, keep one knee bent, lift your leg up a few inches off the ground and hold for 5 to 10 seconds. Your foot is flexed, you're squeezing your quads, bring your leg back down and repeat. Hold for 5, lower it back down, and keep repeating this for 8 to 12 repetitions. When you're finished with the right side, switch to the left. Seated Leg Extension. Now I would sit in a chair but since we're at the gym I'm sitting on a bench. You're going to straighten your leg out in front of you, squeeze the quad and hold this for 30 seconds to one minute. Take a short rest when you're done and then repeat up to 4 times. Eventually you're going to want to work up to hold both legs out in front of you for the required amount of time. 30 seconds to 1 minute. Take a short 30 second rest and repeat. And these are all great exercises to strengthen your quads and strengthen your knee. I'm Sarah Huggins for LIVESTRONG.COM.