Vivian Grisogono

The front-thigh muscles shorten in concentric contraction as you straighten the knee, and pay out in eccentric contraction as you bend the knee and control the reverse movement. Strength in the front-thigh muscles helps to protect the knees.
Position: Sit on an upright chair with a wedge or rolled towel under your knees.
Movement: Straighten one knee to lock it fully, keeping the foot up at right angles to the leg. Slowly bend the knee to lower your foot to the floor again. Relax completely.
Repetitions and frequency: 5-10 times on each leg in turn, 1-2 times a day.
Progression: When the exercise is easy, use an ankle weight or weights boot for resistance. Alternatively, use a knee extension machine and gradually increase the weight resistance.
Note: Avoid pain, and do not do this exercise if you can’t straighten your knee fully. Try to keep your head up and your back straight.
After injury: A late-stage exercise following knee and front-thigh muscle injuries. Also useful following calf, hamstring and hip injuries.