Are we still missing the boat?
In 1984, a study was published in the Archives of Physical Medicine & Rehabilitation by Spencer et al that took the fitness and rehabilitation worlds by storm. In this study, it was revealed that experimental knee joint effusion resulted in inhibition of the vastus medialis, rectus femoris, and vastus lateralis muscles of the quadriceps. Specifically, it was noted that a minimal threshold of only 20-30 mL of saline was necessary to cause inhibition of the vastus medialis as compared to the other two muscles studies. The results of this paper led to a strong emphasis by many professionals on the importance of vastus medialis obliquus (VMO) training in the presence of knee pain and / or injury.
Some of the exercises utilized to train the VMO included:
From the late 90's to the turn of the century however, anterior cruciate ligament, patellofemoral and iliotibial band injuries were being heavily researched, leading many professionals who were on top of their game down a different path. Thanks to biomechanical research investigating jump-landing mechanics, focus had shifted from the VMO toward the gluteus medius (GMED) and maximus (GMAX) musculature. Some of the common buzzwords associated with such research included dynamic valgus and valgus collapse, indicating that perhaps inefficient GMED and GMAX activation and contractions led to unwanted femoral adduction and internal rotation, and subsequently, abnormal stresses sustained by the knee. What was resulted was an increase in open-kinetic chain Jane Fonda type exercises both in rehabilitation clinics and commercial gyms alike.
With a little more critical thinking however, leading professionals were doubtful of the "benefits" of such open chain exercises. Strength and conditioning coaches, especially, were more interested in a functional approach to training and preferred closed chain exercises to combat the unwanted valgus collapse presentation. Mini band walks, x-band walks, monster walks, and crab walks were only but a few of the exercises utilized by coaches and trainers to train the GMED.
Professor Stuart McGill, considered one of the world's leading spine biomechanists, thought differently. Through countless hours of data collection both in his lab and on the field, McGill realized that such a relatively tiny muscle as the GMED could not possibly control frontal plane stability of the hip and knee. It was his assertion that since the "core" acts to CONTROL rather than initiate movement, the contralateral quadratus lumborum (QL) must eccentrically contract to hold the pelvis up (i.e. during the swing phase of walking/running), as opposed to the hip abductor moment created by the GMED. I believe these arguments stem largely from his research comparing trunk muscle activation, lumbar spine motion, load, and stiffness of different strongman events and while I assume it will take more evidence for many of you to drop the minibands, please consider that many previous electromyographic studies have failed to include the QL in data collection (1, 2).
Certainly, some of you may be wondering about the role of the GMAX in dynamic femoral internal rotation control. May I humbly suggest that the greatest contribution of this muscle occurs in situations and movements that warrant double leg stance and single leg deep hip and knee flexion.
Having said all this, in no way am I advocating the use of isolation-type exercises as the staple of rehabilitation and performance training. My objective here is simply to point out that a concentrated focus on the gluteus medius for rehabilitation and training of the knee (for loaded movements) may still in fact be an exercise in futility and that a more dedicated emphasis a little higher up and to the other side may produce more optimal results. For unloaded sports (i.e. running), direct lateral hip emphasis is likely still warranted.