Quoting from Wikipedia, where I make regular monetary contributions. You should too... you will feel much better afterwards using it... I do
In 1964, George J. Goodheart made up Applied Kinesiology through his unique interpretation and application of Muscles: Testing and Function written by two physical therapists Kendall and Kendall.
Applied kinesiologist (right) practising
Applied kinesiology is presented as a system that evaluates structural, chemical, and mental aspects of health by using a method referred to as manual muscle testing alongside conventional diagnostic methods. The essential premise of applied kinesiology that is not shared by mainstream medical theory is that every organ dysfunction is accompanied by a weakness in a specific corresponding muscle, the viscerosomatic relationship. Treatment modalities relied upon by practitioners include joint manipulation and mobilization, myofascial, cranial and meridian therapies, clinical nutrition, and dietary counseling.
A manual muscletest in AK is conducted by having the patient resist using the target muscle or muscle group while the practitioner applies a force. A smooth response is sometimes referred to as a "strong muscle" and a response that was not appropriate is sometimes called a "weak response". This is not a raw test of strength, but rather a subjective evaluation of tension in the muscle and smoothness of response, taken to be indicative of a difference in spindle cell response during contraction. These differences in muscle response can be indicative of various stresses and imbalances in the body. A weak muscle test is equated to dysfunction and chemical or structural imbalance or mental stress, indicative of suboptimal functioning. It may be suboptimal functioning of the tested target muscle, or a normally optimally functioning muscle can be used as an indicator muscle for other physiological testing. A commonly known and very basic test is the arm-pull-down test, or "Delta test," where the patient resists as the practitioner exerts a downward force on an extended arm. Proper positioning is paramount to ensure that the muscle in question is isolated or positioned as the prime mover, minimizing interference from adjacent muscle groups.
"Nutrient testing" is used to examine the response of various of a patient's muscles to assorted chemicals. Gustatory and olfactory stimulation are said to alter the outcome of a manual muscle test, with previously weak muscles being strengthened by application of the correct nutritional supplement, and previously strong muscles being weakened by exposure to harmful or imbalancing substances or allergens. Though its use is deprecated by the ICAK, stimulation to test muscle response to a certain chemical is also done by contact or proximity (for instance, testing while the patient holds a bottle of pills).
"Therapy localization" is another diagnostic technique using manual muscle testing which is unique to applied kinesiology. The patient places a hand which is not being tested on the skin over an area suspected to be in need of therapeutic attention. This fingertip contact may lead to a change in muscle response from strong to weak or vice versa when therapeutic intervention is indicated. If the area touched is not associated with a need for such intervention, the muscle response is unaffected
Nearly all AK tests are subjective, relying solely on practitioner assessment of muscle response. Specifically, some studies have shown test-retest reliability, inter-tester reliability, and accuracy to have no better than chance correlations. Some skeptics have argued that there is no scientific understanding of the proposed underlying theory of a viscerosomatic relationship, and the efficacy of the modality is unestablished in some cases and doubtful in others. Skeptics have also dismissed AK as "quackery," "magical thinking," and a misinterpretation of the ideomotor effect. It has also been criticized on theoretical and empirical grounds, and characterized as pseudoscience. With only anecdotal accounts claiming to provide positive evidence for the efficacy of the practice, a review of peer-reviewed studies concluded that the "evidence to date does not support the use of [AK] for the diagnosis of organic disease or pre/subclinical conditions."
My experience: until I used muscle testing while connected to Source, my results were dismal. I am a scientist at heart, so I did lots of experiments, and the results were contradictory in most instances.
Through frequent communication back and forth with Source, I have mapped out areas of applicability, and conditions of reliability. That is what I use, that is what I teach through my somewhat ad hoc webinars, and videos.
Staying connected while muscle testing requires the tester to have superior control of their mind, their ego, and their attention.
If you are a chiropractor, your results will be better, because you are testing muscles... not using the muscles to test something they don't know about... lol