A Muscle Endurance Training for Knee Cap Pain (Patellofemoral Pain Syndrome)

Knee cap pain (patellofemoral pain syndrome)  is the most common cause of knee pain in runners.  (James, S.L., et al, 1978).  The patella is the proper term for the “knee cap”.  Overusing the knee can soften of the cartilage line on the under-surface of the patella and weaken the quadriceps muscle that move the patella over the knee joint. While recovering from such a condition, it is important to increase quadriceps and hamstrings muscle endurance of the affected leg.  Strengthening the last 30 degrees of knee straightening (extension) endurance in the quadriceps is especially important!

One of the major symptoms of patellofemoral pain syndrome (chondromalacia patellae)  is difficulty climbing or descending stairs, or walking down a hill (Malek & Malgine, 1981).   While stair-climbing may be difficult, due to pain, controlled retraining of the quadriceps muscle will help restore the full ability to climb and descend stairs, plus help stimulate the regeneration of normal cartilage on the patella (Palmoski, et al, 1980).  A training routine for increasing muscle endurance to the knee must be accomplished without provoking sharp pains, as this would negate any strengthening effect.   Traditionally knee muscle strengthening programs suggest using ankle weights to stress the quadriceps, the following program aims at using a more functional activity for increasing the endurance and, not necessarily the size or bulk of the muscles.  The following routine consists of doing isotonic concentric and eccentric step-up/step-down exercises for the knees. This activity also positively  stresses the hamstrings and buttock muscles.  Research by McKenzie, et al indicate that good foot alignment such as what foot orthotics provide, plus core stability training for the buttock muscles improves the effects of muscle endurance training programs.   Lower extremity kinematics of females with patellofemoral pain syndrome while stair stepping. J Orthop Sports Phys Ther. 2010 Oct;40(10):625-32.

To begin:

  1. Get a 4 to 6 inch (10–15 cm) thick block of wood (or other firm material, such as a phone book).  A taller person will require a thicker block, while a shorter person should use a thinner block.  The knee should be at an angle of 30 degrees or less when one foot is on the block while the other heel touches the floor.
  2. On the first day, do a continuous series of step-ups on both the normal and affected legs to determine the maximum number of step-ups you can accomplish per leg.  the Maximum number on the weaker leg will be called MAX.
  3. The PLAN is to do this exercise routine on ALTERNATE days.
  4. ENDURANCE = 60-80 % of MAX for any muscle tested.

The AIM of this particular program is to do three sets of 70% MAX per exercise session.  When starting program, completing three full sets of 70% may be difficult, therefore, do as many repetitions as are comfortable during any given set.

Because a muscle responds to strengthening based on the speed and the degree of joint bending/unbending, it is advisable to do each exercise set at a different speed (rate).

If there is increased discomfort upon completion of an exercise session, apply an ice pack over the knee, using a package of frozen peas, for no more than 10-15 minutes.


  1. Increase the routine to a daily session.
  2. Increase the block height, eventually using a standard stair height.
  3. Increase your 70% MAX, remembering that too many repetitions can lead to further overuse.


  1. 5-10 minutes of stationary bicycling at a constant speed.
  2. Rotational core training on pivoting disc using the Mastermoves Core Training Program (http://mastermoves.com/fred.html)
  3. Swimming with a paddleboard.
  4. Elliptical trainer in “Hill climbing” mode
  5. Physio Ball core stability exercises for the hips and pelvis.
  6. Variations on the yoga “plank” exercises for core training of the lower body.

Fred Samorodin, RPT

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