WHAT IS THE MOST NEGLECTED MUSCLE IN THE BODY AND WHAT IS ITS ROLE IN KNEE AND HIP PAIN?

Blog #4 May 2022

We live in a very health conscious society. We spend a great deal of time, effort and money taking care of our various body parts, for example, our skin, hair, nails and teeth. We run, we swim and we carefully watch our diet in order to take good care of our heart. However, for that part of the body that makes up half our body weight, most of us take it for granted and hardly give it a second thought. I am talking about our skeletal muscles. There are about 640 of them. About half of our brain and spinal cord are devoted to controlling them. If you are suffering from chronic pain, it is highly likely that at least one or more muscles are not healthy and have been neglected for a long time.

This brings us to trying to appreciate the difference between healthy and unhealthy muscles. A healthy muscle contracts smoothly to one end of its range of motion. It can do this under a load without any pain. After a contraction, it can relax fully to the other end of its range of motion. In comparison, an unhealthy muscle only contracts through a limited portion of its range of motion, experiences pain or discomfort when asked to contract under load and does not completely relax after a contraction. It is susceptible to “pull” type injuries especially while contracting under load. 

Probably the most neglected muscle of the body is the rectus femoris. This muscle runs across the front of the hip joint, down the entire front of the thigh and ends in a strong tendon that enters the knee joint. it is part of the quad group of muscles and is shown in front view in figure A.

It serves two main purposes. It flexes the hip by lifting the thigh off the floor and extends the knee by straightening it from a bent position. If there is pain around the front of the thigh or in front of the knee, the rectus femoris is a prime suspect as a cause. Physical therapists will tell you that this muscle is shortened and tight in most adults that are referred for therapy.

The explanation for this is that no matter what exercise regimen we might follow, in any typical day, this muscle is never moved throughout is full range of motion. For example, when we sit in a chair with our feet on the floor, the knee is typically bent at ninety degrees so that the rectus femoris is being held at about the midpoint of its range of motion. Even worse, when we sit in recliner-type chair or when we lie in bed, the rectus femoris is held at its shortest length. So for the better part of every single day, this is how we hold this muscle. It is the unfortunate reality of our sedentary existence.

In a typical sedentary person, the upper end of the rectus femoris which lies across the front of the hip is also shortened. When we sit in a chair, the thigh is bent at a right angle so that the rectus femoris is held somewhere near the middle of its range of motion. Just like its lower end, in a typical day it rarely is fully flexed or fully extended to the ends of its range of motion. For example, to fully extend its upper end, either the thigh or the upper body needs to bent backward at about a thirty degree angle. 

Without a conscious effort, the upper and lower ends of this muscle can spend years just existing in the middle of its range of motion. The end result of this existence is that the entire rectus femoris muscle becomes shortened, filled with contraction spots and is no longer capable of comfortably moving to the endpoints of its range of motion. In this unhealthy state, whenever it is put under load, it is highly susceptible to “pull” type injuries. And it is a leading suspect when there is chronic pain at the front of either the knee or the hip. 

If there is chronic knee or hip pain, there is a way out of it! It involves working to eliminate the contraction spots and performing static stretches on both the lower and upper ends of the muscle so that the muscle can once again comfortably function throughout its normal range of motion. The Book clearly explains exactly how to comfortably do the stretches and how to eliminate the contraction spots by applying sustained pressure to them. Once the muscle has been successfully lengthened, the Book also illustrates dynamic movements that can be performed under load.