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Muscle Imbalance, Part 1: A common, often undetected cause of aches, pains and disability.

By April 29, 2015May 14th, 2020Exercise

One of the most common complaints in adults is discomfort, injury, or some other physical ailments causing aches and pains. Every day millions of Americans treat these symptoms with aspirin, pain-relieving creams, gels, cold and hot packs, and over-the-counter medication and NSAIDs (non-steroidal anti-inflammatory drugs), such as Advil, Tylenol and Aleve. But many people do seek help for their aches and pains, from their family doctors, chiropractors, osteopaths, physical therapists, massage therapists, and even surgery.

While sometimes the problems are remedied quickly, many patients go from one specialist to another without resolution of their complaint. Usually underlying these physical problems is muscle imbalance. And yes, there are relatively simple ways to correct it.

Your body’s muscles are a vital part of overall health and fitness. In total, the muscles are the body’s largest organ, and they aren’t just for lifting, pushing, carrying, moving, or sprinting to get out of the rain. They are responsible for other functions such as helping to pump blood through the body’s miles of blood vessels, immune function, and burning body fat.

There are three different kinds of muscle in the human body, each with different functions:

1. Smooth muscle makes up the walls of the arteries to control blood flow and surrounds the intestines from beginning to end to regulate the movement of food during digestion. These muscles are controlled to a great extent by the autonomic nervous system (the automatic or subconscious control of many body functions).

2. Cardiac muscle is unique to the heart. While influenced by the brain and nervous system, as well as hormones, the heart also contains its own intrinsic mechanism allowing it to beat independently.

3. Skeletal muscle comprises the bulky muscular images we’re so familiar with in fit looking people. Most of these muscles are comprised of a variety of different fibers, primarily the aerobic and anaerobic types. While their basic movement is under conscious control from our brain (with many other actions taking place we’re not always aware of), you can also influence skeletal muscles significantly through exercise, diet, hormones, and therapies. Skeletal muscles are the focus of this article.

Unlike heart muscle, skeletal muscles work because the brain and nervous system control them; as such, it should be referred to as a neuromuscular system, which includes the brain and spinal cord, the muscles, and the nerves that connect them.

In addition to their physical attributes, skeletal muscles influence many areas of metabolism, including fat storage, the liver, and the brain. Skeletal muscles also play a significant role in immune function because of their antioxidant capabilities; they are essentially home to much of our antioxidant protection, given a healthy diet and the intake of foods high in antioxidants. Muscles are even a major source of blood and lymph circulation. This occurs mostly in the red aerobic muscle fibers, which are well endowed with many miles of blood vessels.

The Full Spectrum of Muscle Function

A primary function of muscles is that they move bones and allow you to use your body for standing, walking, running, and every other physical action. When muscles don’t accomplish this task, it’s typically due to some type of dysfunction. In general, the full spectrum of muscle function can range from very loose muscles that are grossly weak with no perceivable contraction, to the other extreme of hypertonic or very tight, spastic muscles. Between these two extremes are a number of other important conditions. But before considering them, it’s important to know how muscles normally work.

Normal muscle function

A muscle’s normal activity is a combination of contraction and relaxation, technically referred to as facilitation and inhibition, respectively. When walking, for example, contraction and relaxation occur continuously throughout the body. When muscles contract, they get moderately tighter while working harder; when relaxed they have less force and also allow the opposite muscle to contract better.

The best way to explain normal muscle function is to feel it working. Let’s use the biceps muscle on the front of the upper arm and the triceps muscle on the back of the arm. The contraction and relaxation of these two muscles, which usually work together to move the elbow, can provide an accurate view of how muscles normally work throughout the body. So try this experiment:

– First, in a relaxed, sitting position, with your left hand feel your right biceps muscle on the front of your upper arm. Then feel the right triceps muscle on the back of your upper arm. At rest, they should both be relatively relaxed—firm but neither tight nor too loose.

– Next, place your right hand under your thigh, then pull upward as if trying to lift your thigh; in doing so you contract the biceps muscle. Now feel the biceps muscle again with your left hand, and it should feel noticeably tighter. This is how a contracted muscle (one that is normally facilitated by the brain) feels.

– While continuing to lift up on your thigh, now feel the triceps muscle on the opposite side of the arm. This should feel much looser than the biceps and even a bit looser (depending on how much you pull up on your thigh) than when at rest. This is how a muscle relaxes itself more to allow the opposing muscle to contract. The biceps muscle is contracted (or facilitated), and the triceps is in a state of inhibition. In fact, without this extra relaxation (inhibition) by the triceps, the biceps could not properly contract.

During a walk, jog or run, this same facilitation and inhibition takes place constantly in opposing muscles, just like the biceps and triceps. It occurs in the quadriceps (front of the thigh) and hamstrings (back of the thigh), the anterior tibialis muscle (front of the leg) and calf muscles (including the gastrocnemius and posterior tibialis), the pectoralis muscles (upper chest and front shoulder) and latissimus (back of shoulder and spine), and so on.

Normal muscle function is the optimal state of the neuromuscular system. It provides the best balance of the physical body—with the right combinations of inhibition and facilitation to produce the most effective physical activity.

Abnormal Muscle Function—Neuromuscular Imbalance

Understanding the normal function of muscles can also give you a better idea of the abnormal. The most common abnormal muscle condition in active and inactive people alike is muscle imbalance, which occurs when two or more muscles don’t contract and relax as they should. This type of problem is referred to as neuromuscular imbalance.

Using the example above when you contracted the biceps and the triceps got looser, imagine if the biceps remained tight and the triceps remained loose even after you released your grip on your thigh. This is very much like the condition of muscle imbalance—except both muscles are in an abnormal state.

A muscle that stays too relaxed is referred to as abnormal inhibition and sometimes called “weak” (although this is not true weakness, which refers to the lack of power). This part of a muscle imbalance can be relatively minor causing minimal impairment, or in some cases extreme to the point of causing severe pain in a joint controlled by that muscle. In most cases, this inhibition causes an opposite muscle to become too tight, a condition called abnormal facilitation. Together, these abnormal muscles—muscle imbalance—can adversely affect the joint(s) they control, the tendons they’re attached to, and other muscles, ligaments, bones, and body areas (such as the pelvic, spine, or head) all over. This will also cause an imbalance in posture and an irregular gait.

The full spectrum of muscle function ranges from extreme weakness to extreme tightness, with normal in the middle. The extremes are usually due to a brain or spinal cord injury; those with cerebral palsy, multiple sclerosis, or who’ve had a stroke typically have this type of muscle weakness and tightness.

The development of muscle imbalance may occur as follows:

• The abnormally inhibited muscle is lengthened, and is often the starting point for many common physical ailments that are not induced by trauma such as falling or twisting your ankle. This muscle weakness itself is often silent. However, you might feel the lack of function produced by it, such as something not right in the knee joint while moving. And, when the muscle doesn’t properly control the movement of a nearby joint, it eventually causes that body part to become inflamed.

• Trauma—from a minor, seemingly innocuous muscle strain, or a major hit or fall that directly injures the muscle—can result in the same abnormal muscle inhibition.

• The other side of abnormal muscle inhibition is tightness (abnormal facilitation). It often occurs as the body compensates to an abnormal inhibition that recently occurred. This tight muscle is often noticeably uncomfortable and sometimes painful, and it can impair movement by restricting flexibility. Tight muscles are shortened, making them candidates for mild, slow stretching; however, in most cases this would be treating the secondary problem as the cause is usually the weak (inhibited) muscle. In addition, in attempting to loosen the tight muscles through stretching (which is not recommended), you risk weakening the inhibited muscle more (because it’s already over-stretched).

Two Types of Muscle Imbalance

Today, health-care professionals, sports coaches, and athletes often use the term muscle imbalance. Unfortunately, there is no consensus about how muscle imbalance is defined.

There are at least two different types of muscle imbalance:

– Neuromuscular imbalance was discussed above, and involves the whole spectrum from brain and nervous system to the muscle itself.

– Exercise imbalance is generally a localized muscle problem, typically due to working one muscle or group much more than another; or using one muscle or group much less than another in daily life. (This is not to say that the brain and nervous system don’t play a role in exercising a muscle, but the term “neuromuscular” differentiates the two types of muscle imbalance for convenience.)

Exercise Imbalance

It’s not unusual for some individuals to define muscle balance and imbalance in terms of strength, making it more a local phenomenon because it reflects muscular exercise. In this case, the problem is too much or too little strength development in one muscle or muscle group compared to another. As an example, this can occur with lifting weights if the biceps muscle is used more than triceps exercises. The result is that the biceps becomes much stronger relative to the triceps. This could make the elbow or shoulder joint vulnerable to injury.

The cause of exercise imbalance can occur from improper weight workouts, performing one-sided-type sports such as tennis, or having a job that requires a high level of physical activity in only one muscle or muscle group. These are examples of using one while reducing the action of another muscle or muscle group causing imbalance. The lack of strength, typically from neglect or disuse, can also contribute to muscle imbalance.

Measuring Muscle Imbalance

Muscle imbalances can’t be easily evaluated using X-rays, CAT scans, or other high-tech devices. But it’s possible to measure the problem in other ways. In general, the “strong” muscle is measured against the “weaker” one:

– For neuromuscular imbalances, evaluations include testing a single muscle or muscle group to determine general contractibility.

– For exercise imbalances, specific measures of strength can be made.

Differentiating between normal deviations is important. The human body is not perfectly symmetrical, and therefore normal variations exist in muscle function and strength. The most common example is the expected difference between muscle strength on the left and right sides of the body—a right-handed person usually has more strength on the right side.

Observing posture and gait, and considering the health and fitness history are two ways of observing both types of muscle imbalance.

Strength versus Power

It should be noted that strength and power are two terms often used together but should be defined differently:

– Strength is defined as the maximum force a muscle or muscle group can generate, such as in lifting a weight. Athlete A can bench press 200 pounds and has twice the strength of athlete B who can bench press 100 pounds.

– Power incorporates a speed factor with strength. Athlete A and B can both lift 350 pounds, but athlete A has more power because he can lift this weight much quicker than athlete B.

The general terms “weak” and “strong” are usually associated with strength. However, these are vague meanings unless related to a previous muscle condition—For example, Athlete A’s leg muscles are stronger now that he is consistently exercising.

Observing posture and gait

When working with patients to assess their muscle function, I would study their standing posture and gait. In fact, just moving around during a walk from the waiting area to my exam room, including the act of standing and sitting provided valuable information about specific muscle dysfunction. Muscle imbalances are represented by excessive deviations in posture—curving of the spine, tilting of the head or pelvis, one-sided rotation of the upper body, or other distortions, some very subtle, others not. Expressing pain in a certain physical position also provides information about a muscle or muscles not supporting the body.

Irregularities in movement are more common with higher levels of activity, especially during exercise and in particular with running which relies on more muscles. One just has to watch athletes on TV or the runners at the end of a marathon or long bike event to see the more exaggerated forms of imbalance: irregular movements, and, in runners, even the erratic sounds of shoes hitting the pavement.

I recall my days as a student, learning about muscle imbalance and which muscles perform specific movements, and the imbalances that cause slight irregularities in gait. Some of my classmates and I would go to an indoor mall and watch people walk by, assessing them with our newfound understanding of human anatomy.


I found that the history of a person’s pain or injury usually provides a significant amount of information regarding which muscles are imbalanced. In today’s health-care environment, however, taking down a patient’s full history is a lost art. This is unfortunate since people knowingly and unknowingly provide many key clues by talking about their symptoms, and a good question and answer session may be the best assessment process that can uncover a hidden cause of a problem and lead to an effective therapy.

A person with knee pain who states he or she twisted an ankle a week before the onset of the problem is making an obvious statement about which muscles might be weak. In this case, one or more of the muscles that supports the ankle that can also influence knee movement, such as the posterior tibialis, could be the cause of the knee pain.

Asking a patient a question such as, “what movement causes pain” can provide important clues about which muscles are at fault. Difficulty with specific movements, for example, such as getting up from a chair, placing a hand on the low back area, or combing hair, are associated with particular muscle weakness.

Other assessment procedures are applicable to one type of muscle imbalance or the other as discussed next.

Testing muscle strength

Exercise imbalance can be measured various ways. The simplest method is through observation. By comparing the bulk of the left and right sides of the thigh, one could sometimes see large differences in muscle mass. This might also include obtaining a measurement of muscle bulk, such as the size difference between left and right lower thigh just above the knee. While muscle bulk does not necessary directly relate to strength, this provides a general measure of imbalance potentially caused by exercise or lifestyle factors—such as too much development in one muscle or muscle group compared to another. Left-right differences in the body usually exist but should not be significant. An example of a normal difference might be a right thigh measurement of 15½ inches and the left 15 inches.

Testing a muscle’s strength is a simple way to measure individual muscles or muscle groups. If you can lift a 50-pound weight 15 times with your right biceps and seven times with your left, it shows you’re much stronger on the right compared to the left. In this case, the difference is probably not within the normal variation of being right-handed. Using your left arm more in the course of daily living could eventually make up the deficit.

Examples of sports medicine measurements

Comparing the strength of certain flexor and extensor muscle groups is common in athletes. An example is the relative strength of the hamstrings on the back of the thigh in comparison to the quadriceps on the front can be measured. This hamstrings:quadriceps (H:Q) ratio is a common assessment. An H:Q ratio less than 0.6 is thought to be abnormal, and this imbalance in strength between the quadriceps and the hamstrings could potentially contribute to knee joint or hip injury.

Likewise, the ratio of biceps to triceps strength has also been used. Studies show that a ratio greater than 0.76 may predict elbow injuries, although this particular study was done observing baseball pitchers.

Information about muscle balance is sometimes evaluated on an electromyographic (EMG) device. This equipment measures the electrical activity of muscles at rest and during contraction. Studies using EMG are commonly used in research and by clinicians to treat various types of muscle problems. Like most other muscle evaluations, there are no clear standards for gathering and assessing different types of EMG findings. However, comparing before and after treatment measurements can be very useful to determine whether improvements are being made and which therapies may be most successful.

Testing neuromuscular function

Generally speaking, muscles involved in neuromuscular imbalance can sometimes be measured using some of the same methods as above. This includes posture and gait, and a history. And, more subtle neuromuscular imbalances are not as easy to observe compared to the significant weakness found in stroke patients.

The size of the muscle in relation to the body’s left and right, or front and back, is not as relevant in the case of neuromuscular imbalances. In fact, strength and neuromuscular function in the same muscle sometimes don’t correspond. A frail elderly person could have poor muscle strength but good neuromuscular function, and a person who regularly lifts at the gym could have neuromuscular imbalance contributing to an injury.

As part of an assessment process, EMG may be useful in evaluating neuromuscular imbalance. Some practitioners, however, also use it as part of their therapy and is an example of biofeedback, defined here as a method of improving muscle function and correcting imbalance by consciously responding to the stimulation of pressure resistance by another person (such as a therapist) against a muscle.

Another form of biofeedback, manual muscle testing, is sometimes used with EMG but often performed separately as an assessment, and at times part of the treatment. Muscle testing is often used before and after therapies such as muscle stimulation, manipulation and massage, to evaluate their efficacies.

Manual muscle testing

As a form of biofeedback, manual muscle testing is commonly used for the evaluation of muscle imbalance, most often employed to evaluate neuromuscular imbalance. It can also be used as therapy.

The first textbook on manual muscle testing appeared in 1949 to assess muscle weakness in polio patients, and gradually, muscle-testing techniques were improved for the evaluation of a full range of muscle dysfunction in all types of individuals. Today, various forms of manual muscle testing are used by tens of thousands of health-care professionals worldwide. Manual muscle testing is also recommended by the American Medical Association’s guidelines for physical impairment.

The objective of muscle testing differs considerably among its users. For example:

• Neurologists perform muscle testing to help evaluate brain and spinal cord function.

• A physical therapist may use muscle testing to rate a patient’s level of disability.

• An athletic trainer may use muscle testing to assess a particular athletic injury.

• Chiropractors, osteopaths, and other medical doctors may use manual muscle testing as a form of assessment for neuromuscular imbalance.

Manual muscle testing involves physically evaluating individual muscles. This is accomplished by first positioning an arm, leg, or other body part associated with a particular muscle’s action. In this position, the practitioner applies force against the patient’s force from that particular muscle. Weakness due to abnormal inhibition may exist if the resistive force cannot properly be maintained, or sometimes if there is excessive pain.

Properly done, manual muscle testing can help differentiate between neuromuscular imbalance, and exercise imbalance. And, it can eliminate the need for EMG and other tests, many of which are much more expensive.

Ten Common Causes of Muscle Imbalance

1. Poor muscle development

This can arise from chronic exercise imbalance (such as lifting weight with certain muscles and neglecting others), poor running gait (which can develop certain muscles more than others), or overtraining (too much workout time and or too much workout intensity).

2. Poor lifestyle habits

This includes performing physical work requiring the use of certain muscles while neglecting others. Being overly right-handed while not using the left hand, and being generally inactive (the couch potato) are two common examples.

3. Micro-trauma

These injuries may be less obvious, such as regularly wearing bad shoes, sitting at your desk or in your car too much, or chronic repetitive stresses such as typing.

4. Acute or chronic localized injury

These injuries are more obvious and include the common muscle strain, a twisted ankle, or traumatizing a muscle from a fall or whiplash-type injury in a car accident.

5. Chronic and acute illness

Including diabetes (reduces neuromuscular function), sarcopenia (reduced muscle bulk with aging), chronic inflammation and related conditions (arthritis, obesity, and many illnesses resulting in significantly reduced physical activity).

6. Neurological disorders

These include brain injuries (such as Parkinson’s disease, stroke, birth trauma, head trauma), and spinal cord injuries (serious trauma that damages the spine affecting the spinal cord such as an auto, bike, or swimming accident).

7. Nutritional factors

Such as low dietary protein, dehydration, anemia, low blood sugar, and general malnutrition.

8. Pain

Whether from unknown sources, or chronic or acute pain from an injury or illness, the presence of pain itself can produce muscle imbalance maintaining a vicious cycle of cause and effect.

9. Aerobic deficiency syndrome (ADS)

Reduced aerobic muscle development can lower overall muscle function causing an imbalance.

10. Stress

Excess physical, chemical and mental stress can directly and indirectly cause muscle imbalance through mechanical and chemical means.

The above items are discussed in more detail in my books and other articles.

Muscles attach to bones through tendons. So when a muscle is not functioning properly, the tendons don’t either. Most tendon problems are secondary to muscles that don’t work well. Likewise, ligaments connect bones to other bones. And muscles have an important support relationship with both ligaments and bones, directly and indirectly. So when a ligament or bone problem exists, there is usually an associated muscle imbalance as well.

The cause of muscle imbalance must be addressed if normal muscle function is to be restored. Often, the body can accomplish this on its own, especially when it’s fit and healthy. Being barefoot is a powerful physical activity that can help the body correct muscle imbalance.

In fact, the body is always self-correcting problems. Even without knowing it, the body is always working to restore muscle balance. During the process of correcting its own problems, the body may show relatively minor symptoms, and often none at all. When your body can’t fix a particular problem, that’s when symptoms appear and an injury develops.

Go to Part 2.