Length tension relationships are at the root of each joint in the body. Our musculature forms a system of levers which pull on the joints at opposing angles to create stability while we navigate position. Healthy length tension relationships exist when our muscular recruitment patterns are optimal. This results in a coordinated synergy of levers to articulate our range of motion. In any given joint, surrounding musculature both facilitates and inhibits a given movement.
Joints are controlled by opposing sets of muscles, agonists and antagonists. These muscle groups balance each other to create motion at the joints. As one muscle lengthens, the other shortens. The quadriceps facilitates extension of the knee by acting as the agonist. The hamstrings, however, have an inhibitory effect on this movement by opposing the quadriceps, acting as the antagonist. The quadriceps and the hamstrings oppose one another, acting as contralateral pressures.
This principle is called Reciprocal Inhibition. So long as this relationship is healthy, stress will be evenly distributed across the knee joint. Herein lies the essence of a length tension relationship.
This relationship between muscle groups is found throughout all joints of the human body, and healthy tissues maintain healthy length-tension relationships at each joint. However, when we suffer an injury, we experience Altered Reciprocal Inhibition, meaning that a restricted agonist inhibits the neural drive to its functional antagonist. This alters neuromuscular patterning and affects movement of the joint in question.
This same relationship holds true in the joints and corresponding muscles of the lumbar spine.
The flexors and extensors of the spine maintain intervertebral stiffness and stability within the joints, and injuries to the low back alter the relationship between these muscles in a very predictable pattern.
Several clinical studies have demonstrated decreased firing of the Transverse Abdominus, Psoas, Internal Oblique, and Multifidi muscles in individuals with Chronic Low Back Pain.
On an individual level, we build the training process to assess and improve length tension relationships. Kinesthetic awareness is a valuable skill which requires cultivation and practice. Through time and proper training, we come to know more of the unique myofascial relationships which dictate joint health, like a personalized fingerprint which provides insight into our exercise programming and volume specifications.
Myofascial restriction presents structural consequences not only to local musculature, but along global myofascial meridians spanning up and down the body. Directing and improving your myofascial structure is a key step in balancing your kinetic chain for more efficient movement, less pain, and optimal performance.