 |
| |||||||
|
| |||||||
Balancing Muscle Groups: A Solution to Repetitive Stress Injuries
by C. Ted Ostrem
In the past few years, there has been a tremendous amount of attention given to the problems associated with Repetitive Stress Injuries such as Carpal Tunnel Syndrome and lateral and medial epicondylitis ("Tennis and Golfer's Elbow"). Patients who suffer from symptoms of these disorders are usually told that the only remedies are to wear splints, which can be clumsy and often do not rehabilitate symptoms, or undergo surgery, which can be traumatic and costly. Alternatively, they are told to stop the activity that's causing the problem, but it's too often a result of an occupational-related activity that they can't stop or a recreational activity that they don't want to stop. Obviously, the patient is dissatisfied with these approaches.
The U.S. Bureau of Labor Statistics reports that the most prevalent and fastest growing occupational injuries are Repetitive Stress Injuries (RSI), formally known as Cumulative Trauma Disorders. RSIs occur when stress and fatigue overpower the body's natural ability to heal itself. RSIs affect different parts of the body such as muscles, tendons, joints and nerves, and they affect them in different ways. Of all of the forms of RSIs, the nerve entrapment disorder known as Carpal Tunnel Syndrome, or CTS, is the most common and one of the most debilitating. Next on the list is lateral and medial epicondylitis, painfully affecting millions of Americans, according to the National Center for Health Statistics.
Too Tight A Tunnel
Carpal Tunnel Syndrome, when caused by
repetitive or sustained activities, acute wrist
angles, vibration, temperature extremes or localized
contact stresses can be prevented. Additionally,
when symptoms have already manifested
themselves they can be alleviated in most cases.
Across the back of the wrist, eight small, irregular carpal bones form the greater part of a circle. Closing the circle on the inner side of the wrist is a tough ligament, the flexor retinaculum, also known as the transverse carpal ligament. Together, bones and ligament form the carpal tunnel through which passes the median nerve, one of three that control the hand. The other two, the ulnar and radial nerves, fortunately pass by on the outside of the carpal tunnel. Also passing through this narrow, rigid tunnel are nine flexor tendons that transmit forces from the forearm to the fingers.
When the fingers are used while the wrist is in a straight or "neutral" position, the flexor tendons glide along the tunnel's walls, lubricated by fluid within their synovial sheaths. If the wrist is bent, in either extension or flexion, their movement becomes like that of ropes dragged roughly back and forth across a pulley. When done hundreds or thousands of times daily, it is possible to experience the tell-tale symptoms of Carpal Tunnel Syndrome. Unlike a rope, the tendons won't fray and snap with wear.
Instead, the tendons and
their sheaths will become irritated and swell up
within the narrow confines of the carpal tunnel,
pressing hard upon the median nerve. Initial symptoms
are usually felt as numbness in the hand, or a
"pins and needles" tingling; maybe there will be a
little swelling on the underside of the wrist. Pain
usually comes later and can be excruciating at
night, even awaking the patient from sleep. Unless
corrective steps are taken, the nerve may be
damaged to the extent that there can be partial or
even complete loss of motor function of the afflicted hand(s).
Repetitive movements can also cause a reduction in the level of natural lubrication within the tendon sheaths, leading to the buildup of friction. This produces swelling and, ultimately, the growth of fibrous tissue that constricts the movement of the tendons. This sets up a destructive cycle within the muscles that increases overall muscle tension. The result is a situation where even greater exertion is necessary to accomplish the same amount of work.
What Caused It?
When caused by "overuse activities" CTS , like most Repetitive
Strain Injuries, has six causal factors:
Even psychological stress adds to the problem by creating muscle tension, which reduces blood flow to hard-working muscles and tendons. Without enough oxygen, these tissues become fatigued and more prone to injury.
To understand how even small stresses can cause major problems, take the example of an average typist who works a six hour day. If he or she types 60 words per minute, that's 18,000 keystrokes each hour, which requires about eight ounces of pressure with each keystroke. At the end of the day, that typist's fingertips have pressed the equivalent of 54,000 pounds. That's 27 tons in one day. Do that day after day, year after year, and, not surprisingly, problems arise. This is a classic definition of Cumulative Trauma.
One of the reasons we are seeing
such an upturn in incidence rates is that
the number of computer users has increased
from five million to 50 million
people in just the past 10 years. That's
half the entire American workforce. And
there will be more than 100 million video
display workers by the year 2000. Computer
users move 40 percent faster than
people using typewriters and do not get
the important rest periods associated with
hitting the carriage return lever after each
line and replacing the sheet of paper at
the end of each page. As a result, the
L.A. Times newspaper has mandated rest
breaks for computer users.
Studies have shown that using the same motions thousands of times daily, year after year, cause major problems for up to 10 percent of the people so engaged. Repetitive jobs that have a basic cycle time of 30 seconds or less elevate the risk of CTS by five times. The same is true for jobs in which 50 percent or more of the work cycle involves similar motion patterns. When high force requirements are added to this extreme repetitiveness, such as that required in many manufacturing jobs, the risk factor rises by 15 times.
A Pattern of Development
The syndrome begins when the
space inside the carpal tunnel diminishes
or when the contents of the tunnel
enlarge. As was previously stated,
CTS is technically a nerve damage
problem that occurs when the nerve
becomes entrapped. However, as it
pertains to repetitive activities, there
are other initial developments occurring
in the hand, wrist, and arm that
lead up to the end effect of nerve degeneration.
The general order of
these developments is as follows:
The forearm contains muscles and tendons that allow the fingers to move. They can be separated into two basic groups: the flexors and the extensors. Flexor muscles and tendons are used during the gripping action or "closing" of the hand and fingers. Extensor muscles and tendons permit the hand and fingers to "open" or extend. The anatomy of the human body accommodates the natural tendency of using the flexors with greater force than the extensors. In other words, in normal daily activities one needs to grab, hold or handle items that require different levels of flexor muscle effort. However, regardless of how much strength is required to hold on to an item, it still requires only the most minimal of effort to let it go, whether it be a pencil or a brick. Therefore, the flexors are much stronger than the extensors. When one becomes involved in an activity that requires an unusual amount of flexor involvement, such as typists, butchers, dentists, bricklayers or other occupations typically associated with CTS, the flexor muscles become too developed relative to their antagonists, the extensor muscles. In other words, the flexors are in a state of hypertonicity and the extensors are in a relative state of hypotonicity. The human body is made up of many "balanced" muscle systems. If the balance of any of these muscle systems becomes significantly altered due to overdevelopment of one part of the system without a subsequent development of its opposing counterpart, then there can be consequences.
Before the median nerve is actually entrapped and damaged by the flexor tendons, the hard structures of bone and ligament of the carpal tunnel itself, there are conditions that are being set up that lead to the final scenario of actual nerve damage. Every time a muscle contracts, there is an opposing, or antagonistic, muscle that must simultaneously relax. When a muscle is repeatedly contracted, it becomes tired. To contract the muscle again will now require more effort than before. When overused, this creates a condition where the muscle remains in a state of semi-contraction even when it is at rest. This is what causes a group of muscles to become foreshortened (relative to their normal length when at rest). In the case of CTS, the result is a reduction in the fingers' original range of motion. When a muscle is in this state of constant semi-contraction, the tendon that attaches to this muscle becomes shorter and thicker. This creates a further crowding in the carpal tunnel which increases pressure even more.
As the flexor muscles are exercised from the repetitive activity, they respond by becoming bigger and stronger. The tendons that connect these muscles to bone are also being subjected to overuse. The result is that they rub against each other, especially in the narrow confines of the carpal tunnel. The consequence of this rubbing is inflammation of the tendon (tendonitis) and/or its protective synovial sheath (tenosynovitis). The body responds by sending more synovial fluid to lubricate the afflicted area. All of these factors lead up to the same end result--swelling. The swollen flexor tendons inside the tunnel have nowhere to expand except into each other and the adjacent median nerve. The final result of this swelling is additional pressure in the tunnel and, of course, on the median nerve itself.
Pressure Verses Blood FlowWe have now described the conditions that cause abnormal pressures in and around the carpal tunnel. While it is true that the abrasion and compression of the median nerve is what causes the nerve to be damaged, the body is constantly responding by trying to heal the affected tissue. The body's chief healing substance is blood, which carries oxygen and nutrients to the afflicted area and carries away waste products. These waste products are highly irritating chemicals that, when not flushed away by the blood, contribute to inflammation. Blood circulates into all tissues, including muscles, tendons and nerves. When sustained contraction of muscles prevents the normal flow of this nurturing blood supply, the normal healing process that repairs the body is greatly impaired. The nervous system, in the human body especially, requires healthy, uninterrupted blood circulation for healing, normal nerve impulse conduction, and intracellular movement of the cytoplasm of the neurone. That oxygen from normal blood circulation is so critical is demonstrated by the fact that the nervous system uses up a full 20 percent of the oxygen available from the blood supply, yet it consists of only two percent of the body's entire mass. Circulation to the farthest reaches of the blood's "plumbing" system of veins, arterioles and capillaries requires that blood pressure be high enough, relative to external pressures on the blood carrying structures. This is accomplished by the body's various structures having pressure gradients that all have higher or lower pressure levels relative to one another.
The proper order of pressure gradients of structures in the carpal tunnel, from highest to lowest, is as follows: epineurial arteriole, capillary, fascicle, epineurial venule, and then the tunnel itself. It has been documented as long ago as 1976 that alterations in this all important order of pressure gradients between the structures in the carpal tunnel is the basis for median nerve compression in the tunnel. Research has also shown that maximal contractions of the wrist and fingers can at least triple the pressure in the carpal tunnel, further aggravating these factors. For example, during wrist flexion, pressures in the tunnel increase by up to 200 percent, whereas when the wrist is held in extreme extension, such as when pushing a heavy object, they increase by as much as 400 percent.
If artificial or abnormal pressures exist that interfere with normal pressure gradients, then blood cannot reach certain tissues, such as the nerve fibers. As pressure increases in the tunnel due to tight muscles and inflamed tendons, the blood-carrying structures collapse, leading to hypoxia, edema and fibrosis of the nerve. Ischemia, or oxygen deprivation, is often a direct by-product of compression neuropathy. This is a condition that causes the neuron itself to degenerate as a consequence of the reduced oxygen rich blood flow. The end result is a nerve that does not receive nutrition, so it will not properly conduct synaptic impulses and cannot heal.
It's All in the Balance
Traditional methods of solving the
CTS problem have often been less than
effective. Anti-inflammatory medications
and splints can bring temporary relief
from pain symptoms, but they do not always
eliminate the cause of the symptoms
themselves. Surgery, a "last resort"
that basically consists of severing the
wrist's transverse ligament to make the
tunnel slightly bigger, is not always effective,
in spite of its expense. For those
who have found relief through surgery,
approximately 80 percent find a return
of the painful symptoms in about two
years and face additional surgeries. This
may in part be due to the fact that most
people who develop CTS because of job-related
activities have to go back to that
same job once they have recovered and
subsequently develop the problem all
over again. Considering the costs,
trauma, and lost work-time associated
with surgery, it should be considered to
be a less than optimal solution. Rehabilitation
by non-invasive means seems
to be a more logical approach. If, as studies
have shown, that one can often experience
a reduction or even elimination
of existing symptoms by balancing the
over-and-underdevelopment condition
of the muscles and tendons through
stretching and strengthening exercises,
then it would seem that would be a
course of action to seriously investigate.
Likewise, if methods of prevention were implemented instead of
merely shrugged
off as non-priorities, then many of today's
CTS cases would never have materialized.
Dr. Donald Millar, former director of the National institute for Occupational Safety and Health (NIOSH), says, "The biggest occupational health and safety problem is the blindness of our society to the benefits of prevention. We have medical care costs escalating out of control, compensation insurance costs escalating out of control, and at the same time, a tremendous growing emphasis on quality. But we haven't penetrated with the notion that prevention is in the best interest of business."
CTS is a perfect example of the old saying "An ounce of prevention is worth a pound of cure." The disorder has a long latency period, symptoms don't appear overnight. Predisposed individuals need to do something about prevention before they get to the stage of obvious symptoms, and the costs of prevention are far less that the costs of so-called cures.
A Different Approach
New techniques and information
must be incorporated into the pool of potential
solutions. The best solutions seem
to be provided by a combination of rest
breaks, job rotation (when possible), and
an exercise and stretching program that
is specially designed for the specific
problem. Preventative stretching and
exercising can help by compensating for
the musculotendinous imbalances that
are evident in those suffering from occupationally
induced CTS. Studies have
shown that productivity goes up and
claims and lost worker-hours go down
for companies that have implemented an
effective exercise program. "Effective" is
emphasized because there are many programs
and products that were not specifically
designed for the particular problem
of CTS and do not take advantage of
the latest physiological information available.
They seem to be designed more for
the purpose of taking advantage of a
commercial market than providing a true
solution. For example, "squeeze toy"
gadgets are available that tout themselves
for the relief of CTS, but they exercise
and strengthen the flexor muscle group,
muscles that are already in a state of overdevelopment from the repetitive activity.
A few products are available that
do focus on strengthening the extensor
muscle group, but most ignore basic concepts
of exercise physiology. For example,
therapeutic putties can be formed
into a ball and then made into a donut
shape or ring. The fingers are then inserted into the ring and extended against
the resistance of the putty.
This needs to
be done for numerous repetitions to build
strength, but the time required to reform
the putty for each repetition can provide
too much rest in between repetitions.
Rubber exercise bands of varying resistances
are available, but for exercising
the relatively weak extensor group, there
needs to be very small, incremental changes in resistance to accommodate
changes in strength levels as conditioning
improves. Even with these tools available,
there has to be professional instruction
for using them properly in order to
see real improvement. There are, however,
products and programs available,
at very reasonable cost, that can be of
real benefit. There are programs, for example,
that retail for under 20 dollars
with satisfaction guaranteed. The concepts
used are both simple and effective
and are explained in a comprehensive
instruction manual. When used regularly
as directed, these lengthen the overdeveloped
and foreshortened muscle
groups (the flexors) that have lost their
original range of mobility due to the repetitive
motions required by the job.
These programs accomplish this with a
simple stretching routine done prior to
the exercises themselves. The stretch is
performed with the arm held straight at
the elbow and enlists the median nerve
into the stretch, this mobilizing the nerve
itself. The simple act of regular stretching
helps to combat the foreshortening
of the overused flexor muscles. Stretching
and mobilizing the nerve also has a
mechanical effect that affects circulation dynamics and nerve transport systems.
The exercises themselves are specifically
designed to strengthen and condition the
extensor muscles and tendons in the forearm.
Each of the exercises isolate these
muscles in a different way, effecting a
total involvement of the extensors. By
strengthening the weaker extensors in the
hands and forearms that have been left
in a relative state of underdevelopment,
the abnormal pressures in the carpal tunnel
and on the median nerve are greatly
reduced, allowing the body's natural
healing processes to function.
Testing has shown that these program stretches and exercises will alleviate or greatly reduce the symptoms of pain, numbness, loss of strength, etc. in most anyone who already has occupationally induced CTS. People who already have even moderate-to-severe CTS symptoms have used such programs with very successful results. Many report that all of their symptoms had been totally eliminated in as little as three to six weeks. One of the important factors in these programs is the ability to adjust the resistance during the exercise. If there is too little resistance, then effective strengthening is not achieved. If there is too much resistance, then not enough repetitions can be performed to get good results. The extensor group is one that few people have ever strengthened against any kind of resistance, therefore relatively little resistance is needed to obtain the desired strengthening effect.
The key to a CTS-specific exercise program is its ability to reduce abnormal pressures, both internally and externally, on the carpal tunnel. The exercise program itself does not heal the damaged and abraded tissues. It does allow the body to heal itself, as it was designed to, by removing the impediment of abnormal pressure gradients between the various anatomical structures inside the tunnel, thus allowing for normal vascularity. In most cases, a person who has already exhibited CTS symptoms will begin to notice a change in their condition in less than two weeks. Within one to three months, depending upon the severity of the symptoms and how well the individual's body responds to exercise in general, the symptoms will either be in total remission or will have been reduced to a great enough degree to allow the person to go about his or her daily activities in a normal fashion.
A Pain in the Elbow
Lateral and medial epicondylitis, or
Tennis and Golfer's Elbow, are the next
most common overuse injuries, first diagnosed
in the late 1800s. Lateral is more
common than medial epicondylitis, and
less than five percent
of those afflicted actually develop the problems through their namesake sports
activities. The potential for problems increases after about age 35 when
decreased levels of glycosaminoglycans (GAG) due to aging lead to decreased
extensibility of the involved tissues.
People
develop epicondylitis from repetitive or sustained gripping, awkward or extreme postures of wrist flexion/extension
and heavy use of the fingers. The
disorder is a matter of inflammation of
one or both of two places near the elbow,
either at the junction of the muscle
and tendon or the junction of the tendon
and bone. Most commonly involved
with lateral epicondylitis is the extensor
carpi radialis brevis (ECRB) tendon. With
medial epicondylitis, the primary
muscles involved are the pronator teres and flexor carpi radialis. Microtraumas
caused by shock or vibration cause slight
tearing of these tissues, leading to the inflammation.
Repeated use of the afflicted
tissues overpowers the body's ability to
heal and leads to the symptoms of pain
and tenderness at the elbow and, sometimes,
the entire forearm. Because the
elbow is notorious for having extremely
poor blood circulation, healing blood
volume is often insufficient for good injury
repair. Damage is often compounded as
the body attempts to heal by layering scar tissue over more scar tissue. This often
causes additional problems of stiffness.
The reason the tissues of the musculotendinous
junction and muscle origin
suffer tearing is that they are being
stressed while at their weakest, most
position. For example, Tennis Elbow, when brought on by
playing tennis, is usually
caused by the backhand stroke.
The wrist is bent down in a
flexed position as it holds the
tennis racquet, ready to hit the
ball. ball hits the racquet,
which is the cause of the vibration
and stress to the tissues, the
extensor muscles in the forearm
are in a stretched out position.
In other words, the cross-section
of the muscle belly is at its
smallest diameter, but it is while
it is in this vulnerable position
that the muscle is being asked
to contract forcefully, to hit the
ball and follow through into
wrist extension. The muscle belly is too weak to counter the force, so
the force is resisted by the next link, either
the musculotendinous junction between
muscle and tendon or the muscle
origin where the tendon connects to the
bone. Because these tissues do not have
the same contractile properties as the
belly of the muscle, they have a tendency
to tear instead of withstanding the force.
In the example of Golfer's (or Pitcher's)
Elbow, the opposite happens. The wrist starts in the position of extreme extension
and contracts forcefully into flexion,
causing the same type of injury but on
the medial epicondyle.
Back to Strength in Balance
Exercise and stretching are again the
best method of preventing this problem
as well as rehabilitating existing symptoms.
Programs are commercially available that stretch the proper muscles and
strengthen and condition the affected
muscles and tendons in the forearm, especially
at the points where the muscles
are most vulnerable to stress damage:
during extreme wrist extension or flexion
when the cross-sections of the muscle
bellies are at their smallest diameters.
The same principles apply as with CTS,
the exercises must be specific to the disorder
and focus on the true causes of the problem. The Law of Specificity of Exercise
dictates that the muscles be strengthened
by exercising them at exactly where
the problem originates. Different stretches
and exercises are used for medial
epicondylitis than for lateral epicondylitis.
Just exercising can actually aggravate
the disorder. Epicondylitis-specific
programs increase the strength levels at
the right places of extreme extension or
flexion and reduce the risk of future
injury while increasing blood supply to the elbow to help heal existing injury.
Again, programs are available
that are extremely effective. Compared
to Tennis Elbow arm bands that,
while offering some temporary relief,
merely create an artificial muscle origin
point to create a future problem,
proper muscle conditioning and balance
offers a solution that lasts.
As with CTS people who are involved in repetitive activities need to understand that to prevent Repetitive Motion Injuries (or to prevent them from reoccurring) they need to be involved in repetitive therapy. There just isn't any way around it. It is a common human tendency to try to use complicated solutions for complicated problems, but every once in a while the most effective solutions may also prove to be the simplest.
C. Ted Ostrem specializes in biomechanics and exercise physiology as it pertains to Repetitive Stress Illnesses. He is currently senior vice president of BioSafe Medical Products, Inc. which is located in Lincolnshire, Illinois.
Published in the 3/97 issue of Physical Therapy Products & the 5/97 issue of Chiropractic Products magazines
|
|
* Same
day and next day shipments are normally the case with the exception of any
out-of-stock items.
** Lifetime
member discounts are subject to member
terms & conditions. Also, use of this site & products sales that
result from this site are subject to our company's
policies & disclaimers
