It is always recommended that you warm up and stretch prior to exercising or participating in sports. Stretching the quadriceps and hamstrings reduces tension on the tendons and may reduce irritation of the knee during activity.
For those individuals prone to irritation and/or inflammation of the plica, it is suggested that activities that repeatedly bend and straighten the knee - such as biking or use of a stair stepper machine – be avoided until you consult with your knee expert.