“A medical diagnosis is often just a name for something that happened to someone else at some other time that happens to resemble what is going on for you right now. It may therefore say little about what the cause is for your problem, and even less about what to do about it.
Muscle testing can help to answer the question,
‘what is the best thing to do for you, right now?’ ”
- Dr. Robert Weissfeld
Muscle testing, as it is employed in BodyMind ReBoot, is used in two ways. The first, which is discussed in some depth in the Effortless Rehab pages, is the testing of isolated or individual muscles for the purpose of determining their state; how the brain is activating them, that is.
In this section, we will be looking at how BodyMind ReBoot uses muscles as a reference from which to gain more holistic information about the function of the body. The use of a muscle test to represent functions of the body began in the 1960s in a method known as Applied Kinesiology (AK), developed by Michigan chiropractor George Goodheart.
As a forerunner to BodyMind ReBoot, AK was followed up by Clinical Kinesiology (CK) in the 1970s and 80s, under the auspices of Oregon chiropractor Alan Beardall. Among many innovations, Beardall pioneered the idea that some of the body''s problematic outputs might be the result of adaptation, and that this adaptation was something that could be treated. Maladaptation, as it is more aptly called, is the use of what is essentially misinformation in the brain to predict the immediate future. These predictions are used to establish our psychological and physiological states.
In a sense, we can call the muscle test a misinformation or stress detector. For instance, knowingly lying has been shown in a double-blind study to cause a normally strong "indicator muscle" to weaken.  Similarly, touching an area on the body that is stressed will also cause a weakness of the indicator muscle. 
Overall the muscle test reflects the brain's immediate response to stress, its current defensive posture, we might say. That posture, which contains particular neurophysiological activations of muscles, organs, and the endocrine system, is based on past learning or adaptation. As such, the muscle test is a way to interact with memories that are being activated in the current moment.
By systematically applying "challenges", sensory inputs that bring the attention of the nervous system to various tissues, thoughts, or feelings, we discern the brain's current defensive thrust. One of Beardall's innovations was the discovery that these inputs, contacting various points on the body and using particular hand and body positions, could form a kind of symbolic language.
Oversimplified, having identified an issue or stress through the weakness, we can then identify things that return that muscle to strength, suggesting treatments that might help resolve the issue or stress.
Muscle testing is therefore not concerned with establishing a "diagnosis" as we usually think of it, rather it brings forth the dysfunction that is occurring in the body. In fact, BodyMind ReBoot is not concerned with gaining an intellectual understanding of the condition, though that understanding may come as a matter of course. Instead, it is bringing the condition, which had been automatically manifesting as a package of (mal)adaptive physiological and psychological responses, to the attention of the brain.
This awareness allows the brain to determine if these responses are really necessary. Having gained that awareness, the responses are reassessed by the brain, generally seeing them as unnecessary. In this way, BodyMind ReBoot is a process by which the brain is allowed to reassess and update its responses.
In the process, BodyMind ReBoot is actually helping the brain to recall its memories. The treatments that are suggested by muscle tests in the session balance the body or activate the nervous system in ways that are contradictory to the current defensive activation. It is known that when a memory is recalled, the presentation of contradictory information may cause the memory to be effectively erased.
Thus, muscle testing in BodyMind ReBoot plays a key role in the erasure of outdated maladaptive defensive routines. These defensive routines seem to be a primary cause of emotional pain and suffering, a major cause of musculoskeletal pain and dysfunction, (as discussed in the Effortless Rehab section), and an indeterminate factor in issues of internal metabolic function.
Why do muscles weaken when the nervous system is made aware of stress?
No mechanism has ever been proven, though at least one has been advanced in the past. A very simple explanation may relate to what is known as the freeze response. When stress is perceived by the brain, the first response of many animals, including humans, is to freeze; to become immobilized and attentive. The freeze response begins in the brain area called the amygdala which is known to be vigilant to threats. This, in turn, activates an area known as the periaqueductal grey, which then sends a signal to the cerebellum, which has the capacity to alter muscle activity. [3, 4]
These changes in muscle strength then may be mediated by the cerebellum, which monitors all sensory input so as to determine the ideal muscular responses.
1. Jensen AM, Stevens RJ, Burls AJ. Estimating the accuracy of muscle response testing: two randomised-order blinded studies. BMC complementary and alternative medicine. 2016;16:492. Accessed 9 Aug 2017.
2. Rosner AL, Leisman G, Gilchriest J, Charles E, Keschner MG, Minond M. Reliability and validity of therapy localization as determined from multiple examiners and instrumentation. Functional Neurology, Rehabilitation, and Ergonomics. 2015;5:365. Accessed 28 Jan 2017.
3. Roelofs K. Freeze for action: neurobiological mechanisms in animal and human freezing. Philos Trans R Soc Lond B Biol Sci. 2017;372. doi:10.1098/rstb.2016.0206.
4. Schmidt NB, Richey JA, Zvolensky MJ, Maner JK. Exploring Human Freeze Responses to a Threat Stressor. J Behav Ther Exp Psychiatry. 2008;39:292–304. doi:10.1016/j.jbtep.2007.08.002.