Manual muscle testing

An important assessment and treatment form of biofeedback

Tens of thousands of health and fitness professionals use some form of manual muscle testing in their work. The objective of muscle testing differs considerably among its users.

Neurologists perform muscle testing to evaluate cranial nerves and motor cortex 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. Many chiropractors utilize manual muscle testing as a form of assessment for all these and other reasons. I have used muscle testing for both assessment and treatment in the form of manual biofeedback (1).

While the purpose of manual muscle testing is widely varied, there is one common feature among all those professionals using it: manual muscle testing is a form of biofeedback. In its broadest definition, biofeedback refers to the process of furnishing information in the form of a physiological variable – in this case, muscle function (2, 3). Testing muscle function involves sensory input and motor output. Other physiological variables may coexist during muscle testing, including verbal, auditory, visual and proprioception.

For over 30 years, I have utilized various aspects of biofeedback in clinical practice, including treating patients with common muscle imbalances, patients with brain and spinal cord injuries, professional athletes and others. These specific biofeedback approaches include the use of heart rate monitors for helping athletes train more effectively and for overweight patients to increase fat-burning, the use of electromyography (EMG), stimulation of alpha brain waves using electroencephalography (EEG), and manual biofeedback with its extensive use of muscle testing. Manual biofeedback simplifies the application of most forms of muscle testing while helping to expand the scope of most currently employed “techniques” that utilize manual muscle testing.

The term biofeedback was coined in the 1960s by scientists who trained human subjects to consciously alter their body function through sensory input to the brain. Since then, biofeedback is often associated with the use of electronic monitoring, such as EMG, EEG, skin conductance and temperature. Long before mechanical biofeedback techniques emerged, natural biofeedback mechanisms were built into our nervous systems – a key feature in our development with early humans using it instinctively for survival. For example, sensing uncomfortable temperatures, humans sought ways to adapt through clothing, shelter and fire; and walking on rough surfaces led to the development of protective footwear.

Both manual muscle testing and manual biofeedback use no mechanical sensors or computerized biofeedback programs; they rely only on the hands of the practitioner to evaluate and measure muscle function. In other words, manual biofeedback integrates the practitioner’s sensory system as the primary sensor.

In brief, the procedure of manual biofeedback begins with neuromuscular assessment, including the careful implementation of muscle testing. If abnormal muscle function is found, in the form of abnormal inhibition (weakness), the practitioner uses manual biofeedback – much the same way as the initial muscle testing assessment – to restore muscle function. While isolating the weak muscle as during muscle testing, the patient is taught to contract and resist as the practitioner gives verbal cues and the appropriate isometric resistance against the weak muscle’s direction of movement. The patient resists as much as possible for several seconds and is given short interval rest breaks. This is repeated as the practitioner moves the limb to a new position, and eventually through positions in the full range of muscle motion. The full scope of manual biofeedback includes assessment and treatment followed by appropriate home recommendations when necessary.

Biofeedback can help patients with neuromuscular problems learn to voluntarily control skeletal muscle (4). This may enhance neural plasticity in patients with brain injury (such as cerebral palsy and stroke) and spinal chord injury (5). Common local muscle injuries are often treated with various biofeedback-type therapies that incorporate manual muscle testing (6, 7). The neurological mechanisms responsible for these improvements are not always clear. But for many years we’ve known that feedback activation by sensory means (visual, auditory, proprioception, etc.) may stimulate unused or underused synapses for motor control, possibly creating new sensory engrams resulting in improved function (8).

As a form of biofeedback, muscle testing is commonly used for the evaluation of neuromuscular dysfunction in the chiropractic, medical and other professions (6, 7, 9), and is recommended by the American Medical Association’s guidelines for physical impairment (10). The first textbook on manual muscle testing appeared in 1949 to evaluate muscle weakness in polio patients, with newer editions in common use today for the evaluation of a full range of muscle dysfunction (11). When incorporating accurate manual muscle testing, and thus eliminating the need for EMG equipment, manual biofeedback becomes an uncomplicated therapy for chiropractors.
Manual biofeedback benefits patients with neuromuscular problems; from common local muscle imbalance to more serious disability associated with brain and spinal cord injury. In addition to causing muscle-related signs and symptoms, these conditions are also associated with common spinal problems, especially as part of the “joint complex dysfunction” (12). The majority of patients with physical ailments fall into one of three categories:

1. Local muscle dysfunction, a common cause of physical disability, is often associated with some form of muscle trauma from a fall, an overstretched (so-called “pulled”) muscle, or twisted ankle. Micro-trauma is even more common; it’s the accumulation of minor physical stress affecting a muscle, often unnoticed while it’s happening, eventually causing a more obvious muscle imbalance. Too much sitting, repetitive motion injury and walking in poor-fitting shoes are common examples. Local muscle dysfunction can result in minor annoying discomfort to serious or chronic pain or disability. Local muscle dysfunction is also associated with some level of spinal and/or brain dysfunction because of the delicate sensory-motor relationships between muscle and spine/brain.
2. Brain injury can occur at any age, even before birth, and may be due to trauma, reduced oxygen or nutrient supply, congenital and metabolic defects, or infections. Specific examples of serious brain injury include stroke, cerebral palsy and Down syndrome, while relatively minor physical problems such as just being uncoordinated or “clumsy” have some associated brain dysfunction. Almost all types of brain injury result in muscle dysfunction.
3. An incomplete spinal cord injury is often due to physical trauma such as from a serious neck or back injury. It can adversely affect the nerves innervating a specific muscle or muscles reducing their function. Spinal cord injuries can cause a wide range of problems, from relatively minor physical ones to very serious disabilities.

When a brain, spinal cord or local muscle injury occurs, there is usually a specific pattern of weak and tight muscles that follows. The primary problem is thought to be muscle weakness (muscle inhibition), which immediately causes another muscle, typically the antagonist, to become tight (muscle over-facilitation). The tightness is the most noticeable sign of disability and often the most symptomatic regarding pain. For example, the biceps muscle flexes the elbow, and its antagonist, the triceps, extends it; when one weakens the other typically tightens. In a patient with a stroke or other brain injury, a hyper-flexed elbow position (and often other joints) is a common sign of disability. A standard medical approach is to treat the tight flexor with medication, Botox injections, or even surgery. But because the abnormally inhibited (weak) triceps may be the primary cause of the abnormally over-facilitated (tight) biceps, the results of treating the tight muscles are often ineffective. In this discussion, neuromuscular weakness is not necessarily associated with the lack of power, but rather, muscle dysfunction due to neurological deficits. Increases in muscular power, which can also increase the size of the muscle, typically occur after muscle function is improved and the patient begins utilizing more muscle movement in everyday activity (9).

One unique feature of manual biofeedback is its use in patients with severe neuromuscular deficits. For example, a stroke patient may have lost control of certain muscles, or a child with cerebral palsy may have muscles with zero contraction. In both cases, opposing muscles are typically hypertonic. Restoring muscle function – even minimal contraction obtainable during an initial treatment – can help begin reducing tightness in hypertonic muscles. Manual biofeedback addresses the full spectrum of muscle function – from muscles with no detectable activity, or zero contraction, to those muscles with normal function (where improvement is associated with increases in the number of muscle fibers stimulated during a single contraction).

Manual biofeedback can help expand the scope of most muscle testing-based techniques, of which there are many types practiced in the chiropractic profession. For example and in addition to the problems noted above, it also offers an approach to treat the ‘weak’ muscle(s) of a TMJ problem; it provides a way to directly improve brain function, which in turn can correct many muscle imbalances that effect posture and gait; and, it can often eliminate the need to treat various other elements commonly employed in various muscle testing-based techniques, reducing treatment time.

Conclusion

Manual biofeedback combines manual muscle testing with the basic physiological biofeedback model for a useful clinical therapy that can help improve poor muscle function due to brain, spinal cord and local muscle injury. It can expand the scope of most muscle testing-based techniques and be applied to a wide range of patients, including those with common aches and pains to those with more serious physical ailments, including special-needs children and disabled adults. In addition, manual biofeedback is especially useful as a preventive tool to help avoid neuromuscular imbalances that can potentially increase morbidity and mortality, and reduced quality of life.

References

1. Maffetone, P. Manual biofeedback: a novel approach to the assessment and treatment of neuromuscular dysfunction. J Altern Med Res 2009;1(3), in press.
2. Dorland’s Illustrated Medical Dictionary. 28th edition, p 1596. Philadelphia: WB Saunders Co. 1994.
3. Dorland’s Medical Dictionary online: www.mercksource.com.
4. Basmajian JV. Research foundations of EMG biofeedback in rehabilitation. Biofeedback Self Regul 1988;13:275-98.
5. Huang H, Wolf SL, He J. Recent developments in biofeedback for neuromotor rehabilitation. J Neuroeng Rehab 2006;3:11.
6. Schmitt WH, Cuthbert SC. Common errors and clinical guidelines for manual muscle testing: “the arm test” and other inaccurate procedures. Chiropractic & Osteopathy 2008;16:16.
7. Walther DS. Applied Kinesiology Synopsis, 2nd edition. Pueblo, CO: Systems DC, 2000.
8. Wolf SL. Electromyographic biofeedback applications to stroke patients. A critical review. Phys Ther 1983;63:1448-59.
9. Maffetone P. Complementary Sports Medicine. Champaign, IL: Human Kinetics, 1999.
10. American medical association: guidelines to the evaluation of permanent impairment, 6th edition. 2007.
11. Kendall FP, McCreary EK, Provance PG. Muscles, testing and function, 4th edition. Baltimore, MD: Williams & Wilkins 1993.
12. Seaman, DR. Joint complex dysfunction, a novel term to replace subluxation/subluxation complex: Etiological and treatment considerations. J Manipulative Physiol Ther 1997; 20(9):634-644.