What´s The (Trigger) Point?
Trigger points, are hyper-irritable knots located in soft tissues (e.g. muscles and fascia). They are characterized by palpable nodules in bands of muscle fibers with characteristic referred pain patterns to broader areas, sometimes distant from the trigger point itself.
Many manual therapists (e.g. chiropractors, physical therapists and massage therapists) focus on identifying trigger points as a source of musculoskeletal pain, and eliminate these point through a variety of hands-on therapies.
Dr. Janet Travell was one of the first to describe a trigger points. She observed that:
- Trigger point Pain was related to discrete, irritable points in skeletal muscle or fascia
- Trigger points could be felt as a nodule or band in the muscle, and could elicit a twitch when stimulated
- Palpation of a trigger point reproduces the area of pain, and the pain radiates in a distribution typical of the specific muscle harboring the trigger point.
- The pain cannot be explained by findings on neurological examination.
A Trigger Point assessment typically considers the history of onset, subjective symptoms such as pain patterns and objective findings including abnormal range of motion, muscle weakness and pain to palpation.
Usually there is a taut band or nodule in a muscle containing trigger points,which elicits a twitch response by running oneś finger perpendicular to the muscle’s direction.
The twitch response often activates the “all or nothing” response in a muscle that causes it to contract.
Activation of trigger points may be caused by a number of factors, including acute or chronic muscle overload, activation by other trigger points, systemic disease, psychological distress, muscle imbalances, trauma, nerve irritation, or infections.
In addition, nutritional inadequacies, poor diet, stress, mechanical dysfunction and poor sleep hygiene can all perpetuate trigger points.
When trigger points form, they can cause muscles to shorten, thereby affecting the tendons at bony insertion points. This can result in tendinitis, fasciitis and bursitis. They can also pull on ligaments associated with the muscle and can cause pain deep within a joint where there are no muscles.
Because trigger points upset the optimum length-tension of a muscle, they affect muscles strength and neuromuscular efficiency (the ability of a muscle to produce force, reduce force and stabilize a joint)
It has been hypothesized that trigger points form from excessive release of acetylcholine, a neurotransmitter involved in muscle contractions. In the case of a trigger point acetylcholine produces an ongoing depolarization of muscle fibers, leading to a sustained muscle contraction.
These sustained contractions compress local blood supply, affecting the energy needs of the local region. This in turn produces substances that irritate nerves and can produce localized pain within the muscle.
Many trigger points have pain patterns that overlap, and some create reciprocal cyclic relationships that need to be treated extensively in order to remove them.
Trigger point therapy can involve deep pressure, massage, vibration, ultrasound, electrostimulation, injection, dry-needling, “spray-and-stretch” using a cooling, Low Level Laser Therapy and stretching techniques.
In 1979, a study by Czech physician Karl Lewit reported that dry needling had the same success rate as anesthetic injections for the treatment of trigger points. He called this the ‘needle effect’.
For a treatment to be successful, a therapist must:
- Identify and deactivate all the trigger points within a zone
- Stretch tonic muscles that are facilitated/overactive after the trigger points are deactivated *
- Strengthen phasic muscles that are inhibited/underactive after the trigger points have been deactivated *
- Treat the surrounding fascia
*Functionally, muscles can be classified as “tonic” or “phasic”.
The tonic system consists of the flexors. The phasic system consists of the extensors.
The tonic muscles are prone to tightness or shortness, and the phasic system muscles are prone to weakness or inhibition.
Both tonic and phasic muscles can have trigger points, but often for different reasons. Because of the interrelated reciprocal relationship between these types muscles, a 3 dimensional approach should be taken when performing trigger point therapy. This includes:
- Deactivating the overactive/facilitated tonic muscles followed by stretching
- Deactivating the underactive/inhibited phasic muscles followed by isolated strengthening
- Addressing the synergists
- Mobilizing the affected joints
- Prescribing appropriate corrective exercise
Bruising and soreness may occur after trigger point therapy and can last 1-3 days. This can be managed by contrast hydrotherapy, voodoo flossing (see prior blogs) and nutritional supplements, such as vitamin C, magnesium and bromelain.
Trigger Points and Acupuncture Overlap
There is a strong correlation between the locations of trigger points and classical acupuncture points. Trigger point dry needling could be equated to a western, neuroanatomic version of acupuncture, especially when it comes to musculoskeletal pain and injuries.
Prevalence of Trigger Points
According to Travell, approximately 90% of patients with pain who presented to a pain clinic had associated trigger points. Are you one of them?
Gunn, C. C. (1996). The Gunn approach to the treatment of chronic pain.Intramuscular Stimulation for Myofascial Pain of Radiculopathic Origin. Second ed. New York: Churchill Livingstone.
Davies, C., & Davies, A. (2013). The trigger point therapy workbook: your self-treatment guide for pain relief. New Harbinger Publications.
Lewit, K. (1979). The needle effect in the relief of myofascial pain. Pain, 6(1), 83-90.
Simons, D. G., Travell, J. G., & Simons, L. S. (1999). Travell & Simons’ myofascial pain and dysfunction: upper half of body (Vol. 1). Lippincott Williams & Wilkins.