Muscles are responsible for generating motion. They generally span 1 or more joints and have at least one antagonistic muscle, meaning a muscle which produces the opposite effect. When they receive input from the brain through the nervous system, they contract, whilst the opposing muscle must elongate to counteract that.
An example of this is picking up a hay net. As you lift up the hay net, your bicep contracts, pulling your wrist up towards your shoulder. One of the antagonistic muscles of that muscle is the triceps muscle. As the bicep contracts, the triceps elongates.
When your horse performs an action, specific muscles are activated to not only perform that activity, but also to balance the rest of the body.
Back to the hay net example, as you pick up a heavy hay net in your right hand, your right bicep contracts, and your core stabilises to shift weight towards the left side of your body. This stops you from toppling over.
No muscle works alone. Every muscle is connected to at least one other set of muscles by fascia.
When describing fascia to horse owners, I often compare it to a link of sausages. The sausage meat represents the muscles, and the casing represents the fascia. The individual sausages are connected by the casing, and because of that casing, the link of sausages moves together. However, if one part of the link is pulled out of place, it affects the rest of the sausages too.
11 myofascial lines (sausage links) have been identified in horses (1). Some muscles are part of multiple myofascial lines. The lines are formed in such a way that each line is responsible for a specific function. Whilst one line is responsible for flexion of the spine, another is responsible for extension of the spine and another is responsible for twisting of the spine. Multiple lines can be used at the same time.
What is myofascia?
Basically, myofascia is connective tissue which encapsulates muscles. This allows muscles to connect to other muscles, slide and glide over each other and act in reducing force transmission. The slide and glide is made possible through the presence of hyaluronic acid.
I have never heard of a vet diagnosing a horse with a myofascial problem, so why is it so important?
The nerve supply in fascia is 6 times richer than that in muscles (2) meaning that it is extremely sensitive to external stimulation. They respond to a number of different stimuli, such as vibration, temperature, pressure and pain. Long term stimulation of the fascia results in chronic pain with decreased sliding and gliding and a reduction in the ability to reduce force transmission. This means that the structures attached to that particular myofascial line are more predisposed to injury.
As the myofascia starts to lose its slide and glide ability, it becomes tighter around muscles and eventually becomes stiff (3). This results in the muscle which that particular myofascia surrounds losing the ability to function to its maximal potential. Due to the fact that multiple muscles are connected to a single myofascial line, if one muscle’s myofascia becomes stiff, the rest of the line is negatively affected.
Therefore, if the myofascia of one muscle in the line which flexes the back becomes stiff due to chronic tightness, the horse will struggle to fully flex the back and develop back pain.
How do you test these lines?
Testing is based on functional tests, for example comparing the range of motion in the hocks, ability to perform a sternal lift or whether the front legs can be stretched forward without a bend in a knee. The lines can also be tested by swaying the horse by its tail and putting pressure on certain parts of each line - if the line is tight, the swaying stops.
How do you treat the myofascial lines if they are tight?
Every myofascial line has a specific anatomical treatment point. I treat these specific points with 3B laser and short acupuncture needles and this should generally result in immediate improvement.
I use myofascial release as a complimentary treatment together with veterinary chiropractic and Chinese and trigger point acupuncture. All three modalities work through the nervous system, with the aim of improving the horse's biomechanics and movement. This is done either to improve performance or during rehabilitation following injury. An exercise plan needs to be incorporated into the horse's exercise plan to ensure that that specific myofascial line continues to be stretched and to reduce the likelihood of the recurrence of that myofascial tension.
Elbrønd, V. and Schultz, R., 2021. Deep Myofascial Kinetic Lines in Horses, Comparative Dissection Studies Derived from Humans. Open Journal of Veterinary Medicine, 11(01), pp.14-40.
Van der Wal, MD, PhD, J., 2009. The Architecture of the Connective Tissue in the Musculoskeletal System - An Often Overlooked Functional Parameter as to Proprioception in the Locomotor Apparatus. International Journal of Therapeutic Massage and Bodywork, 2(4).
Wilke, J., Macchi, V., De Caro, R. and Stecco, C., 2018. Fascia thickness, aging and flexibility: is there an association?. Journal of Anatomy, 234(1), pp.43-49.