Functional Anatomy Part 3The Quadriceps

In Parts 1 and 2 of this miniseries I discussed the the key functions and training considerations of the glutes and hamstrings, respectively.  As you may recall, I mentioned that the glutes and hamstrings are often lengthened and weak.  The opposite is true of the quadriceps as they are often tight and overactive because most people tend to rely on the strength of their quadriceps and adductors to produce lower body movements over their glutes and hamstrings.  This issue is compounded by the fact that the quadriceps are antagonists to both the glutes and hamstrings, so the tighter the quads get, the more inhibited the glutes and hamstrings become.  This in turn can lead to overuse injuries such as quadriceps and patellar tendonitis and can also increase the incidence of knee and lower back pain.

The quadriceps are four separate muscles that fuse into one common tendon (the quadriceps tendon) to insert on the patella.  Because of their common insertion point, all four muscles have similar functions.  The origin, insertion and function of each muscle is listed in the table below.

 

Vastus lateralis, medialis and intermedius work synergistically at the knee joint to produce extension.  The lateralis and medialis muscles also contribute, although minimially, to other movements, as mentioned in the chart above.  The distal porition of the vastus medialis muscle, called the vastus medialis obliquus (VMO), serves the important function of patellar stabilization.  When the VMO doesn’t fire correctly or is out of balance with the lateral structures (i.e. vastus lateralis, lateral retinaculum and iliotibial band) it can contribute to abnormal patellar tracking and quad-chain knee pain.  That being said, if you have quad-chain pain don’t focus too much on training your VMO as it is near impossible to isolate and it isn’t the only contributing factor.  Instead, focus on foam rolling the lateral structures, improving motor control and strength of the gluteal muscles and stretching the quads (both at the hip and knee) and calves.

The rectus femoris is distinct from the vastus group because it originates on the ASIS (part of the pelvis) and therefore crosses both the hip and knee joints.  It isn’t necessary to isolate the hip flexion function of the rectus femoris (outside of the rehab setting) because the hip flexors are generally tight and overworked as is.  In addition, when the rectus femoris is short and stiff, it limits hip extension and inhibits the glutes, which puts an increased stress on both the knees and lower back.  The quads are best trained with integration exercises that focus on both knee and hip extension (i.e. squat and lunge variations) as these strengthen the glutes and hamstrings at the same time.

Examples of quadricep integration exercises:

Front Squat (and all other squat variations) DB Step-up DB Reverse Lunge (and all other lunge variations)

Examples of quadricep isolation exercises:

Leg Extension Band Terminal Knee Extension

Considerations for Training

It is generally unnecessary to include quadricep isolation exercises, such as leg extensions and terminal knee extensions in your program unless you have or have had quad-chain pain or injuries.  For specific knee pathologies, these exercises can be beneficial but must also be combined with foam rolling (and other forms of tissue release) of the lateral leg structures, hip mobility drills, quadricep stretching and glute strengthening.  As always, complex exercises trump isolation exercises!  Squats, deadlifts, lunges, step-ups and other multi-joint exercises will give your far more strength, size and functionality than leg extensions.