Quad Isolation Exercises for the Knee

The knee joint is susceptible to injury from sudden turns, twists or overuse from contact sports, running or everyday activities. Strengthen the knee and increase protection with quad isolation exercises, which aim to support the sensitive knee structures. Quad isolation exercises focus predominantly on contracting the quadriceps, the large muscle on the front of the thigh. The quad muscle attaches to the knee or patella structures via muscle tendons. Add quad isolation exercises to your strength-training routine a few times a week.

Isolate the quadriceps muscles to strengthen the knees with an isometric quadriceps exercise. In an isometric contraction, you contract a muscle without lengthening it. Perform this exercise by lying on a mat on the floor with one knee bent and the other leg stretched out in front of you. Place a rolled-up towel underneath your knee so that the knee bends slightly and the heel of your foot lightly touches the ground. Squeeze or tighten the quad muscle at the front of the thigh, which will cause your heel to lift off the ground. Hold approximately three seconds before relaxing to start position; rest and repeat 10 times.

The squat is considered to be one of the best exercises for the quadriceps. Although the squat elicits a co-contraction with the hamstrings, a study in the "Journal of Strength and Conditioning Research" showed that the parallel squat had higher EMG activity in the major quadriceps muscles, the vastus lateralis and medialis muscles, versus the leg extension exercise. According to Peak Performance, this implies that the squat works the quadriceps the hardest. It is imperative to use correct form when doing squats, as improper form can compromise the knee joint due to extra pressure on the femur and tibia. Stand tall with feet hip-width apart, abdominal muscles engaged and arms down by your side. Slowly start to bend your knees and lower yourself into a squat position. Your knees should be in alignment over the ankles and never extend past your toes. Avoid undue pressure on the knees by sticking your buttocks out as you lower and keeping squats to less than 90 degrees. Repeat 10 times; rest and repeat.

Stepups isolate the quads to help strengthen and protect the knee joint. Perform stepups at home by placing a small block on the ground in front of you. Place a chair in front of the block with the back of the chair facing you to hold on to during the exercise if needed to steady your balance. Step up and place the left foot on the block, keeping your knee in alignment with the second toe. Step up with the right foot following the same form. Pause before stepping down with the left foot, followed by the right. Continue to slowly step up and down in this manner as you focus on contracting the quadriceps muscle with each motion. Repeat 20 times leading with the left foot, and 20 times with the right, for a total of three sets.

Wall slides are a challenging quad exercise to strengthen the knee joint. Observe caution when doing this exercise to avoid any deep knee bending that could aggravate the knee joint, particularly if there is an injury. Start by standing tall with your back against a wall and feet shoulder-width apart. Walk feet out in front of you approximately 18 to 20 inches. Slowly slide down the wall until you reach a 45- to 60-degree angle in your knees. The angle will depend on any injuries and the integrity of your knee joint. Hold at the bottom for five to 10 seconds before sliding back up the wall and resting. Repeat 10 times for a total of two sets.