Vastus Medialis Obliquus Muscle (VMO) “Isolation” Exercises Fact or Myth?

At Elite Physical Therapy and Sports Performance we take pride in the fact the we are well ahead of the curve with out treatment techniques compared to the rest of the traditional PT world, but we also acknowledge that it is important to use evidence based treatment techniques.

Evidence based practice is the buzz word in PT circles but despite this strengthening/isolating the VMO continues to be utilized as a way to decrease knee pain and improve function.   PT’s and physicians alike continue to prescribe strengthening for the VMO muscle of the quadriceps group even though the research has proven this concept to be faulty and ineffective.

This short article was written by a couple PT friends of mine in New York (one of which is in the PT and Strength and Conditioning Halls of Fame!) showing once and for all that you can not isolate the VMO, nor should you bother trying when it comes to solving knee pain.

Enjoy!

Originally posted on SportsRehabExpert.com

Robert A. Panariello MS, PT, ATC, CSCS
Timothy J. Stump MS, PT, CSCS, USAW

Professional Physical Therapy
Professional Athletic Performance Center
New York, New York

Patellofemoral pathology is a fairly common condition observed in clinical setting. The treatment philosophy of some rehabilitation professionals to resolve this painful condition may include the prescription of exercises in the attempt to isolate the Vastus Medialis Obliquus muscle (VMO). Although this VMO exercise isolation “myth” has been negated at least 20 years ago (1, 2) it continues to presently endure.  During this attempt to isolate VMO activity, some designated exercises executed include but are not limited to the following:

  • Quad sets
  • Terminal open chain knee extension exercises
  • Straight leg raises (SLR) with external rotation of the lower extremity

These exercises may or may not be performed with the adjunct application of electric stimulation.

Although these exercises will enhance the strength of the quadriceps muscles, likely assisting in resolving the patient’s knee pathology, this is not due to isolation of the VMO. The case some clinicians formulate for the performance of SLR with external rotation is based on the false premise that by externally rotating the femur will result in further activation of the VMO.

The knee is a hinge joint and during the execution of a SLR, the force of gravity will act in a perpendicular manner between the knee and ground surface. The quadriceps mechanism will now be required to resist the resultant force attempting to flex the knee as this is the only contractile soft tissue structure that is capable of resisting that force.  The quadriceps mechanism like any other dynamic structure can only resist this external force via the neural activation of the muscle group.  The external rotation of the femur gives rise to the placement of stress on medial collateral ligament (MCL), a static stabilizer of the knee.  This treatment philosophy actually removes stress from the very muscle(s) the clinician is attempting to enhance.  As an example a patient with a diagnosis of polio, a condition affecting the anterior horn of the femoral nerve or a patient with a quadriceps tendon rupture can still perform a SLR when externally rotating their femur based on the static stabilizing properties of the MCL.  Therefore one may inquire why would a clinician who is attempting to activate and enhance the quadriceps muscle group perform the SLR exercise in external rotation.

The anatomy and neuroanatomy of the quadriceps muscle group

The quadriceps muscle group is comprised of the rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis. The vastus medialis (VM) is located at the medial aspect of this muscle group and has been reported to consist of two separate components, the proximal vastus medialis longus (VML) and the distal vastus medialis obliquus (VMO) (4). The neuroanatomy of the quadriceps muscle complex reveals an innervation from the femoral nerve.  The femoral nerve is comprised of large motor units that innervate all four heads of the quadriceps without individual fine motor unit innervation of the separate muscle heads.  Therefore, since the VMO does not have a distinct and separate nerve innervation, it is not possible to “isolate” this muscle from the other quadriceps muscles via a specific exercise performance. The most beneficial way to enhance the VMO is to incorporate the same exercise philosophy used to improve any other muscle or muscle group, the application of unaccustomed stress. The application of unaccustomed yet safe levels of stress is simply known as the “overload principle”. This may be accomplished in two ways; expose the patient to higher levels of unaccustomed resistance or overload them by increasing the velocity of the movement. Both methods will result in a positive adaption of the entire quadriceps muscle group.

Since stress transpires throughout the kinetic chain of the lower extremity during the performance of ADL’s as well as athletic endeavors, the activities prescribed for patellofemoral pathology should also include exercises for both the hip and ankle. “Critical thinking” is a requirement for the approach to the patient’s optimal exercise selection and treatment design. The health care professional’s obligation to provide optimal treatment does not include the application of myths during the patient’s plan of care.

References

1. Cerny K “Vastus medialis oblique/vastus lateralis muscle activity ratios for selected exercises in persons with and without patellofemoral pain syndrome”, Phys Ther (8):672-83, 1995
2. Malone T, Davies G, Walsh WM, “Muscular control of the patella” Clin Sports Med 21(3); 349-362, 2002.
3. Hubbard JK, Sampson HW, Elledge JR, “The Vastus Medialis Oblique Muscle and Its Relationship to Patellofemoral Joint Deterioration in Human Cadavers”, J Ortho Sports Phys Ther 28(6):384-391, 1998.
4. Weinstabl R, Scharf W, and Firbas W, “The extensor apparatus of the knee joint and its peripheral vasti: anatomic investigation and clinical relevance”, Surg and Radiological Anat  11(2): 17-22, 1989

Robert A. Panariello MS, PT, ATC, CSCS
Rob Panariello PicRob is a Founding Partner and Chief Clinical Officer with Professional Physical Therapy presently with 44 facilities in the New York and New Jersey Metro areas and the Professional Athletic Performance Center located in Garden City, New York. He has Bachelor Degrees in Physical Therapy and Physical Education/Athletic Training from Ithaca College in Ithaca, NY. He also holds his Master’s Degree in Exercise Physiology from Queens College in Queens, NY.

Rob has more than 30 years of experience in the related fields of Sports Physical Therapy, Athletic Training, and the Performance Training of Athletes. His experience includes the study of the Science of Strength and Conditioning of weightlifters and various sport athletes in Bulgaria, the former Soviet Union, and former East Germany. He previously held the positions as the Head Strength and Conditioning Coach at St. John’s University of New York (1986-1995), the World League of American Football NY/NJ Knights (1991), and the WUSA NY POWER Women’s Professional Soccer League (2001-2002). He continues to rehabilitate, athletic performance train, as well as serve as a consultant to many NFL, NBA, MLB, NHL, Collegiate and University teams, coaches, and players.

Rob has more than 60 peer reviewed Orthopedic and Sports Medicine Research, Sports Physical Therapy Research, and Strength and Conditioning Journal Articles and Book Chapter publications. He has also presented his research at the International World Confederation of Physical Therapy in Washington, D.C. He is nationally renowned and lectures throughout the country with regard to the related fields of Sports Physical Therapy and the Performance Training of Athletes.

Rob received the 2015 APTA Sports Physical Therapy Section Lynn Wallace Award for Excellence in Clinical Education, the prestigious National Strength and Conditioning Association’s Presidents Award in 1998 and was elected to the USA Strength and Conditioning Coaches Hall of Fame in 2003.

Tim StumpTimothy J. Stump is a partner with Professional Physical Therapy, and is also a founding partner with the Professional Athletic Performance Center. He  has more than 20 years of experience in the related fields of Orthopedic and Sports Physical Therapy, Strength & Conditioning, and Performance Training of Athletes of all levels of competition. Tim’s experience includes the successful participation as a nationally ranked competitive strength athlete in the sports of Powerlifting and Weightlifting from 1990-2010. He continues to actively participate in these sports as a coach and mentor to many athletes.

Tim has published several peer-reviewed original research articles and has presented his research at the APTA National Conference and at CSM. Tim was also awarded the Jacob & Valeria Langeloth Foundation research grant for studies on ACL functional outcomes while employed at the Hospital for Special Surgery. Tim was the 2012 recipient of Columbia University’s Award for “Leadership in Clinical Education” and co-chairs Professional’s Clinical Affiliation Program with over 64 school contracts providing PT, PTA, ATC and Exercise Physiology students with quality clinical affiliation experiences.