Question: what exercises can i do with a sprained mcl?
Answer: Sit with your affected leg straight and supported on the floor or a firm bed. Place a small, rolled-up towel under your knee. ... 
Tighten the thigh muscles of your affected leg by pressing the back of your knee down into the towel.
Hold for about 6 seconds, then rest for up to 10 seconds.
Repeat 8 to 12 times.