Muscle
is the largest organ in the human body, and accounts for about 50%
of its weight. There are approximately 400 muscles (there are
individual variations), and any one of those can develop trigger
points which can refer pain and cause dysfunction. Symptoms can
range from intolerable agonizing pain caused by "active" trigger
points, to painless restriction of movement and distortion of
posture from "latent" trigger points.
The answer to "What Are Trigger Points?" is:
research it still underway. But many characteristics have been
observed for decades by researchers all over the world. With new testing
methods and equipment, in the last ten years much has been learned about
the physiology of trigger points. And even though not every mechanism is
known, patients get better when their trigger points are treated!
More Trigger Point
Information
When pressed, trigger points feel like
"knots" or tight bands in the muscle, and are usually very
tender. Healthy muscles usually do not contain knots or tight
bands, are not tender to pressure, and when relaxed, they feel soft and
pliable to the touch, not hard and dense, even if you work-out. When trigger
points are present, on the microscopic level, part of the muscle fiber is
contracted into a small thickened area, and the rest of the fiber is
stretched thin. Several of these muscle fiber contractures in the same area
are probably what we feel as a "knot" in the muscle. These muscle fibers are
not available for use because they are already contracted, which is why you
cannot condition (strengthen) a muscle that contains trigger points. The
sustained contraction probably leads to the release of sensitizing
chemicals, producing the pain that is felt when the trigger point is
pressed. Eventually some of the structural changes may be irreversible if
trigger points are left untreated for long enough. The contractile portions
of the fiber in the middle of the knot may separate and retract to each end,
leaving an empty portion of the cell in the middle.
Trigger points may refer pain both in the
local area and/or to other areas of the body, and common patterns have been
well-documented and diagramed. These are called "referral
patterns." Approximately 74% of the time trigger points are not
located where you feel symptoms, and working on the area you feel symptoms
does not give you relief. These referral patterns do not necessarily
follow nerve pathways. Pain levels can vary depending on the stress
placed on the muscle and any of other the perpetuating factors that keep
trigger points activated. Tingling, numbness, or burning sensations are more
likely due to nerve entrapments, which may be a result of trigger points
entrapping the nerve.
If the trigger point is "active," it will
refer pain or other sensations. If it is "latent," it may cause a
decreased range-of-motion and weakness.8
Active trigger points often start with some impact to the muscle, such
as an injury, poor posture or body mechanics, repetitive use, or a nerve
root irritation. Any of the perpetuating factors can also indirectly
activate trigger points and make you more prone to developing
trigger points that are initiated by impacts to muscles. Active trigger
points may at some point cease causing pain, and become latent. Latent
trigger points can easily return to being active trigger points, often
leading the patient to believe they are experiencing a new problem, when
in fact it is an old problem being re-aggravated. Latent trigger points
can be reactivated by overuse, over-stretching, chilling, or any other
of the perpetuating factors. (The chapter on Perpetuating Factors can
be found on the Pain Relief with Trigger Point Self-Help Flashdrive)
In a study of thirteen healthy individuals with
the same eight muscles being examined in each subject, two people had
latent trigger points in seven of those muscles, two people had latent
trigger points in six muscles, three had latent trigger points in five
muscles, two had latent trigger points in three muscles, two had latent
trigger points in two muscles, two had latent trigger points in one
muscle, and only one person didn't have latent trigger points in any
of the eight muscles! This means that most people have at
least some latent trigger points, which could be easily
converted to active trigger points. This also means that some
people are more prone to develop problems with muscular pain than others.
With pressure on the trigger point, you can often
reproduce the symptoms, but being unable to reproduce the
referred pain or other symptoms by applying pressure does not rule out
specific trigger points. I still work on the trigger points
that could be causing the problem, and if my patient improves, even
temporarily, I assume that one of the trigger points I worked on is
indeed the source of the problem. For this reason, I don't work on all
the possible trigger points in one session, since I won't know which
trigger point treated actually gave the patient relief.
Trigger points can cause symptoms not
normally associated with muscular symptoms, such as sweating,
ringing in the ears, dizziness, urinary frequency, buckling knees, and
tearing of the eyes.
Trigger points may cause other muscles
fibers to contract. They will also cause weakness and
loss of coordination of the involved muscles and an inability of the
muscles to tolerate use. Many people take this as a sign that
they need to strengthen the weak muscles, but unless trigger points in
the affected muscle are inactivated, strengthening (conditioning)
exercises will likely encourage the substitution of other muscles,
further weakening and de-conditioning the muscle with the trigger
points.
Trigger points limit range-of-motion due
to pain. Some muscles are more likely to have a larger degree
of restriction than others. Once trigger points are relieved,
range-of-motion is restored.
Muscles containing trigger points are
fatigued more easily, and don't return to a relaxed
state as quickly when use of the muscle ceases.
Patients are often surprised that the same area
on the opposite side is also tender, since that side isn't causing them
pain. Over half the time, the opposite side is actually more
tender with pressure. Unless it is a recent injury, usually
both sides eventually get involved (i.e., if the right mid-back is
painful, there are also tender points on the left mid-back). For that
reason I almost always work on both sides and tell patients to do the
self-help on both sides. One possible explanation is that after the
initial increase in sensitivity with trigger point activation, and the
problem becomes chronic, the body releases pain-masking chemicals and
numbs the side of the original pain out somewhat (hypoesthia), and that
has not yet happened on the opposite side.
Women are more likely than men to develop
trigger points. I have noticed this is particularly true in
menopausal women. Some teenagers (of both sexes) going through puberty
also seem to have a tendency to develop trigger points, leading me to
believe there is a connection between hormonal changes and one potential
cause of trigger points.
People who exercise regularly are less
likely to develop trigger points than those who exercise
occasionally and overdo it.
Part of the current hypothesis about the mechanism
responsible for the formation of trigger points is the "energy
crisis component." The sarcoplasmic reticulum is a part of the cell
responsible for storing and releasing ionized calcium. The
type of nerve ending that causes the muscle fiber to contract is called a
"motor endplate." This nerve ending releases acetylcholine, which tells the
sarcoplasmic reticulum to release calcium, and then the muscle fiber
contracts. If it is operating normally, when contraction of the muscle fiber
is no longer needed, the nerve ending stops releasing acetylcholine and the
"calcium pump" in the sarcoplasmic reticulum returns calcium into the
sarcoplasmic reticulum. If a trauma occurs or there is a marked increase in
the nerve endplate release of acetylcholine, an excessive amount of calcium
can be released by the sarcoplasmic reticulum causing a maximal contracture
of a segment of muscle, leading to maximal energy demand and impairment of
local circulation. If the circulation is impeded, the calcium pump doesn't
get the needed fuel and oxygen to pump calcium back into the sarcoplasmic
reticulum, and the muscle fiber continues to contract. This vicious
cycle continues until there is outside intervention that stretches the
contracted portion of the muscle fiber. The areas at the ends of
the muscle fibers (either at the bone or where the muscle attaches to a
tendon) also become tender as its attachments are stressed by the
contraction in the center of the fiber.
For a list of things that cause and keep trigger
points going, see the section on perpetuating factors. (The chapter
on Perpetuating Factors can be found on the Pain Relief with Trigger
Point Self-Help Flashdrive)
"Thank you Valerie for a truly informative
and valuable webinar. Once I saw the advertisement for the webinar
I looked at Valerie's books and bought all of them from Amazon - they
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filled with valuable information. I not only found lots of new
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own copies as they are so useful. I'll be looking for a live
conference in the Philadelphia area (sooner or later you'll get here).
Best wishes to you Valerie.
Thanks again."
MaryEllen Velahos, L Ac., Dipl. Ac.
The Center for Acupuncture and Traditional Medicine
