The patient lies on their back with one arm stretched straight up toward the ceiling. The doctor presses slowly on the wrist for about two or three seconds, and the arm holds firm. Then the doctor asks the person to place the other hand on the spot on the hip that often hurts, and presses again with exactly the same force. This time the arm drifts down. People are usually surprised right away. Their arms are strong, they carry a 20-liter water jug up the stairs every week, and yet a light press from the doctor brings the arm down.
A few seconds is not long enough for a muscle to lose its strength and then recover. As Schmitt and Yanuck explain it, what has just changed is the way the nervous system is controlling the muscle at that moment, and muscle testing is a way to pick up that change. So muscle testing in Applied Kinesiology (AK) is a way of reading neuromuscular reflexes.
How the 0–5 scale differs from AK muscle testing
Every neurological examination includes a muscle strength check. The patient contracts or extends a muscle group, the doctor resists, and then scores it from 0 to 5. A muscle that does not contract at all scores 0. Being able to lift the arm or leg against its own weight, but not yet against resistance, scores 3. Normal is 5. This scale helps detect clear damage such as weakness or paralysis after a stroke, a compressed nerve root, or a disease of the muscle itself. Many people who come in for back pain, poor sleep or long-lasting fatigue still score 5 in every muscle group.
AK muscle testing asks a different question. The doctor places your arm or leg in a position that isolates one muscle. You hold still, and the doctor gradually increases the pressure over a few seconds to see whether the muscle locks in quickly enough and holds the position. A muscle that scores 5 on a neurological exam can still fail to hold in this test. Its maximum strength is unchanged. It is only that the nerve signal to the muscle is being held back at that moment.
Schmitt and Yanuck (1999) gave these two states names: facilitation, when the nervous system is opening the way for the muscle to work, and inhibition, when the signal to the muscle is being held back. The two authors describe how AK muscle testing picks up these changes when different sensory stimuli (from the skin, the joints and so on) are introduced. The doctor then compares the results with anatomy and neurophysiology to understand what is going on.
A balance scale in the spinal cord
Inside every muscle are muscle spindles, tiny sensors lying among the muscle fibers. They keep reporting to the spinal cord whether the muscle is getting longer or shorter, and whether it is being stretched quickly or slowly. In the spinal cord, the motor neuron that controls that muscle receives messages from the spindles, and at the same time from the skin, the joints, the internal organs and the brain. Whether the muscle responds strongly or weakly depends on the sum of all these inputs at each moment.
Picture the motor neuron as a balance scale with two pans. One pan holds the signals that push the muscle to work, the other holds the signals that hold it back. A swollen knee, the skin around a painful spot, a worry filling your mind and sent down from the brain: each one adds a little weight to one pan or the other. When the doctor presses on the wrist, the spindles report that the muscle is being stretched. Whether the muscle resists in time, and whether its hold under the doctor’s hand is strong or weak, depends on which way the scale is tipping at that moment.
Touch the sore spot, and the muscle changes at once
That is why the doctor can add one stimulus and then test the same muscle again. You place your own hand on the area suspected of having a problem (therapy localization), or the doctor presses gently on a joint in a particular direction (challenge). Sometimes you hold a small amount of a mineral or a medicinal substance in your mouth, or simply smell it (Walther, 1981, pp. 45–50). Sometimes you are asked to recall something that is making you tense. If a muscle that was holding firm gives way, or a muscle that was giving way holds firm again, that stimulus has reached the nervous system.
With the same kind of testing, the clinic also checks minerals, medicinal substances and stress levels in the brain; the step-by-step method is in our article Is Applied Kinesiology safe? Understanding muscle testing.
Pulse diagnosis and muscle testing
In Vietnam, people know the image of a physician resting three fingers on a patient’s wrist and staying silent for a while before speaking. When taking the pulse, the physician relies little on outward appearance, because someone with rosy cheeks can still have a weak pulse. Muscle testing works the same way. An arm toned by weight training does not yet tell you how the nervous system is controlling it on the morning of the exam.
At Tam Duc, the doctor takes the pulse and looks at the tongue as part of the four examinations before muscle testing, and puts the two sources of information side by side before drawing a conclusion. The pulse and muscle testing rest on two different theoretical foundations. So the doctor does not mechanically translate results from one into the other, and gives more weight to the places where both point in the same direction.
What muscle testing adds to the diagnosis
Following the three sides of the health triangle
The clinic looks at illness through the health triangle: structure (bones, joints, muscles, nerves), chemistry (nutrition, micronutrients, hormones, medications you are taking) and mind. According to Rosner and Cuthbert (2012), muscle testing gives the doctor information on all three sides and is always used together with standard diagnostic methods.
Take someone who sits a lot and has had lower back pain for a long time, with imaging that shows nothing significant. When that person touches a joint in the pelvic area, the muscle being tested changes its response, and the doctor thinks more about the structural side. In another person, a weak muscle holds firm when they hold a mineral in their mouth. The thinking then shifts toward chemistry, and the doctor may suggest further lab tests. In someone else, the muscle weakens every time they think about something weighing on them, and the mental side needs to be included in the treatment plan. Often several sides are involved at once. Muscle testing helps the doctor know where to start, whether with acupuncture, moxibustion (warming points with burning mugwort), an herbal decoction modified for each person, changes to nutrition, or exercises.
Alongside lab tests and imaging
Schmitt and Yanuck (1999) regard muscle testing as an additional step; the neurological examination and standard diagnostic methods keep their full role.
Each side has a fairly clear job. An X-ray or MRI captures the shape of bones, discs and soft tissue, while a blood test measures the level of a substance at one point in time. These results, together with ultrasound, show whether there is physical damage and which values are off. Muscle testing shows function, that is, how the nervous system is handling that condition and how the body responds to each stimulus right at that moment. Normal lab results with an abnormal muscle response are a reason for the doctor to keep looking, not enough to say you are healthy. Confirming or ruling out an organic disease (one with a physical cause that tests can show) is the job of lab tests and imaging, and the clinic does not hand that job to muscle testing. The order of the examination and treatment steps is on our Our Approach page.
Evidence on reliability
Manual muscle testing has been part of medicine for more than a century. Cuthbert and Goodheart (2007) traced it back to 1915, when the first article about it was published in a peer-reviewed scientific journal. After reviewing more than 100 studies, the two authors found the test reliable and of good clinical value for neuromusculoskeletal problems. For AK muscle testing specifically, a systematic review by Soares and colleagues (2025) reported reliability ranging from moderate to very strong for one shoulder muscle and three hip muscles. The name of each muscle is in our article Is Applied Kinesiology safe? Understanding muscle testing.
These results come from experienced testers who follow the correct procedure. Pressing in the wrong direction or too quickly can give a different result. That is why the test needs a doctor trained in AK, who knows what question they are asking the nervous system with each press.
Worth keeping
- During muscle testing, hold the position with moderate force for a few seconds; there is no need to compete with the doctor’s hand;
- A muscle giving way during a test does not mean you are weak, so feel free to ask the doctor which stimulus just made that muscle change;
- If your arm drifts down in a position that feels normal to you, don’t worry; the doctor will ask what you were touching or thinking about at that moment;
- On the day of your visit, bring all the imaging, ultrasound and lab results you have, even the ones marked normal;
- Feel free to mention the things that are making you tense, because the mental side also shows up in muscle testing;
- When the doctor suggests lab tests or an ultrasound, have them done first, before starting treatment;
- Decide what to eat and drink together with your doctor, and don’t rely on videos about testing your own muscles at home.
Next time you are lying on the examination table and see your arm drift down, go ahead and ask the doctor what the last stimulus was and what it says about the painful spot. What paperwork to bring, and what to eat and drink on the morning of your visit, are covered in our article What to bring and how to prepare for an Applied Kinesiology visit.
Dr. Dinh Ngoc Duc (MD, MSc in Traditional Medicine) is responsible for the medical content of this article.
References
- Schmitt WH, Yanuck SF. Expanding the neurological examination using functional neurologic assessment: part II neurologic basis of applied kinesiology. Int J Neurosci. 1999;97(1-2):77-108. https://doi.org/10.3109/00207459908994304
- Rosner AL, Cuthbert SC. Applied kinesiology: distinctions in its definition and interpretation. J Bodyw Mov Ther. 2012;16(4):464-487. https://doi.org/10.1016/j.jbmt.2012.04.008
- Cuthbert SC, Goodheart GJ. On the reliability and validity of manual muscle testing: a literature review. Chiropr Osteopat. 2007;15:4. https://doi.org/10.1186/1746-1340-15-4
- Soares JR, Stieven FF, Rocha CSDS, Miranda IF. Reliability of Manual Muscle Testing in Applied Kinesiology: A Systematic Review. J Manipulative Physiol Ther. 2025;48(6-9):862-870. https://doi.org/10.1016/j.jmpt.2025.10.007
- Walther DS. Applied Kinesiology, Volume I: Basic Procedures and Muscle Testing. Pueblo: Systems DC; 1981. Chương “Chemical and Nutrition Testing”, tr. 45–50.
