- Emily Skinner
Trigger Points
What are they?
'Trigger points occur when there is a combination of motor nerve irritation and a build-up of lactic acid, usually within the belly of the muscle'.
The term originates from the fact that when pressure is applied to a particular point, a pain signal is often sent to other parts of the body and referred pain is observed. This is why when I locate a trigger point I will often point out the muscle fasciculations seen elsewhere to you.
Or in one case a client told me they could see fasciculations in their horses shoulder when I had located a trigger point in the hamstrings!).
They can be found within muscles that overall feel very supple. This is why a thorough palpation, particularly in a perpendicular direction to the muscle fibres, is vital during assessment and treatment.
Why do they develop?
Trigger points may occur due to:
Muscular tension/overuse - this can be related to inadequate stretching or rest (which leads to fatigue), or it may be related to compensatory movement patterns from conditions such as osteoarthritis.
Overexertion/stress of the nervous system.
Poor circulation - decreased circulation, and therefore oxygen supply and lymph removal, can occur in muscles which are hypertonic or hypotonic. This can contribute to an accumulation of toxins which can irritate the nerve endings.
Acute or chronic muscle, tendon, ligament, joint, or nerve injuries.
Clinical Signs
Localised twitch response - this is an involuntary spinal cord reflex.
Referred pain - this occurs due to the link between the muscle loci located in the trigger point region and their connection with the spinal cord.
Research studies have demonstrated that generalised pain behaviours or pain responses in one area may not have a localised source:
Research by Bowen et al. (2017) found that higher severity trigger point scores were found in horses with an owner-reported history of girth-aversion behaviours.
Horses with clinical signs of back pain were found to have trigger points located within their back and hindlimb muscles (longissimus dorsi and middle gluteal) in a study by Long et al. (2020).
Trigger Point Release Therapy
Effleurage - this is a massage technique which utilises consistent light strokes to warm up the muscle and encourage relaxation.
Pressure - a light pressure is then applied to the are of tenderness or the nodule found during palpation. Your therapist will then hold this pressure until they feel the muscle relax and soften. This can take a few seconds for acute trigger points or up to a few minutes for chronic trigger points. Effleurage may be needed between pressure applications (approximately every 30 seconds) for more chronic trigger points to help with circulation.
Observation - continual observation of the horses body language and facial expressions is key to determine the right amount of pressure to use.
Drainage - once the trigger point has been released effleurage should be used again accompanied by light friction. This will help to increase circulation and therefore, the supply of oxygen and nutrients to help the muscle heal, along with the drainage of any toxins through the lymph system.