Muscle testing comes out of the larger field of Applied Kinesiology. It is simply a way to allow the body and the subconscious mind to respond to ideas.
The theory goes like this: Any major muscle that is well isolated (meaning there are not too many other compound muscles simultaneously engaged), will respond to subtle electrical shifts that go off in the body. If a client holds an arm out forward, strengthening their deltoid muscle and a practitioner pushes down on the arm, the muscle will bounce back, resisting the pressure. But if an idea is presented that the client is incongruent with (such as having a male say that he is a female) the muscle will respond differently. The incongruence of the idea causes a slight energetic shift in the body and instead of bouncing back the muscle will give way or go “weak.” Because of this simple body response, muscle-testing can be used as a rudimentary tool for accessing stored trauma content in the client’s system that is fueling psychological symptoms.
A common error in the use of muscle testing is the assumption that all muscle testing responses are facts. The secular or new age community assumes incorrectly that the subconscious mind is infallible. The subconscious mind is a good database, cataloging one’s life experiences/emotions but it is not a seat of wisdom or good judgment. It does not have “all divine wisdom.” Data and wisdom are not the same things. The subconscious operates out of very fear-based, almost infantile judgment and cannot be looked to as the source of all the answers. Its strength is that it catalogs one’s life experiences like a hard-drive. Its data is exhaustive about one’s own experiences, the emotions that were stored in the body from trauma and how they are fueling the symptoms. But a muscle test is only an indicator, not a “fact.” That distinction is important.
With all of its weaknesses understood, it remains a useful tool in accessing subconscious trauma and relieving emotional symptoms. But the proof is always in the fruit of the work not in the muscle test.