Why should you focus on the musculotendinous junction when trying to reduce tone and/or lengthen a muscle? And why should the force be applied slowly? Well, it’s all about a focus on the muscle receptors, particularly the Golgi tendon organs and the muscle spindles, to engage a physiological response to change muscle tone and length.

These two receptors work together to create a healthy muscle length, tension relationship to avoid injury. In essence, the Golgi tendon organs, which are situated about the musculotendinous junction (MTJ), reduce muscle tension (reduces contraction) when stimulated. The muscle spindle, found in the muscle bellies, increases muscle tension (increase contraction) when the muscle increases in length, and the rate it increases in length.

So when applying a shear force to a muscle, the area in which you do so, the rate at which you apply the load and amount of time you hold the technique, can become very important to your outcome. Let’s discuss this further.


Where to apply your force

Applying a shear palpatory force about the MTJ, creating tension through this area will create a reaction from the Golgi tendon organs. When a muscle contracts, they produce tension at this point. We can create the same tension with our hands. The Golgi tendon organ recognises both the rate of tension and the amount of tension and will send signals to the spinal cord quantifying the amount of tension in this region. When the tension threshold is reached, it triggers a lengthening reaction, relaxing the muscle, inhibiting contraction, reducing the chance of injury. Hence the application of shear load to this area will reduce muscle tension by increasing the activity of the Golgi tendon organ.

Applying force to the muscle belly may have the opposite effect. This is where the muscle spindles are concentrated. Muscle spindles will react to the muscle stretching by causing a contraction of the muscle ( a message is sent to the spinal cord and the spinal cord sends a message back to contract the muscle), reducing overstretching and muscle damage.

Hence where you apply your force can have different physiological effects.


Why do I need to hold this force for a prolonged period of time?

There are two potential reasons for this.

Firstly, when applying a load/force or a stretch through a muscle, not only are the Golgi tendons activated (reducing muscle contraction) but also the muscle spindles are activated, increasing muscle contraction (it’s a war down there! Well, it’s a dual-action that constantly updates how much muscle contraction is needed to keep the muscle healthy and not injured). The Muscle spindles send a message to the spinal cord to resist too much change to the muscle length. The spinal cord responds by creating some muscle contraction. Hence we have a bi play with these two receptors. The belief is that the sustained pressure about the MTJ, eventually the force being applied through the Golgi tendon eventually over rides the muscle spindle activity and the muscle therefore relaxes.

Secondly, if you hold a stretch for a long period of time, the muscle spindle habituates, becomes accustomed to the new length, and reduces it signalling to the spinal cord. This in turn reduces the contraction of the muscle.

Hence when you are trying to reduce muscle tone, the length of time you hold this shear force, creating muscle tension, is very important to the receptor component of muscles.


Why do I need to apply the force slowly?

The muscle spindle not only records how much stretch is being applied to a muscle but also the rate of stretch. The quicker a muscle is being stretched, the more the muscle spindle will create a contraction to avoid further stretching. Hence if you apply the force slowly about the MTJ, this muscle spindle reaction can be avoided, and the contraction will be less. Hence you won’t be fighting against the contraction you have created yourself!


Know your anatomy

With that knowledge, you can now apply a shear load with some more objectivity. But are all muscles the same? Nope. Hence you will have to understand each muscle to accurately apply such techniques. For instance, the rectus femoris has a central tendon and therefore Golgi tendon organs along its length. Whereas a gastrocnemius has a distinct distal transition from muscle to tendon about its mid-portion.

Some muscles are longitudinal, and others have muscle fibres running in all sorts of directions, depending on their role around the body. So, get to know your muscle anatomy and get better results accordingly.