Running 24 – Normal scans, but long runs still hurt: how we examine runners

The running shoes in the corner have worn down unevenly at one heel. You have had scans, rested for two weeks and done all the rehab exercises. The short runs all went smoothly. Then comes the week you build up the distance, and the pain returns to exactly the same spot: a stab on the inner side of the knee in the last few kilometers, tightness in the back of the thigh when you speed up, or an ankle that suddenly gives way as you change direction on a rocky stretch of trail (a mountain path). You go back to the doctor: the scans are still normal, and on the examination table every muscle tests strong.

Some people only show the problem while they are moving, and a scan cannot capture that. At Tam Duc Clinic, road and trail runners are examined with Applied Kinesiology (AK), a way of testing the strength of each muscle by hand to see how the nervous system is controlling it, combined with traditional medicine, both while standing still and right after a run.

Scans are taken lying still

X-rays and MRI capture structure: bone, tendons, ligaments. Running, on the other hand, is the work of the neuromuscular system: with every stride, many muscle groups have to switch on and off in the right rhythm. A muscle working below threshold, meaning it is not strong enough to hold the joint at the moment it is needed, may only show itself when it is tired, under load, or when you change direction suddenly. Lying on the examination table, it still passes the test.

In recreational runners, the most consistent predictor of injury is a previous injury in the past 12 months (Saragiotto and colleagues, 2014). Running-form features such as impact forces or step rate predict almost nothing about who will get injured (Peterson, 2022; Malisoux, 2022). From this, the clinic follows one direction: to understand why someone keeps getting hurt, you have to examine that very person while they are moving.

Before muscle testing: signs that call for imaging or referral

The first step is always to look for signs that fall outside what AK or herbal decoctions can deal with. With bone fractures from overload (stress fractures), X-rays are often still normal in the first weeks, and MRI is much more sensitive (Magee and Manske; Joyce and Lewindon, 2016). A normal scan is not enough to keep running if you have:

• Pain at one point on a bone that is tender to press, gets worse, and also hurts at rest or at night;
• Hip or groin pain when bearing weight or hopping on one leg;
• An ankle sprain on the trail with tenderness at the ankle bones, the base of the 5th metatarsal (the outer edge of the foot) or the navicular (the middle of the foot, on the inner side), and you cannot walk four steps on your own;
• A “pop” at the back of the heel and being unable to rise onto your toes;
• Urine as dark as cola, or severe muscle swelling and pain after a long run;
• Chest pain or fainting while running;
• In female runners, periods that have stopped for three cycles or more, or repeated stress fractures.

In those cases, the doctor orders imaging, tests or a referral to a specialist, and does not prescribe yet. On long run days, drink only when you are thirsty. Someone who is confused and nauseous after a run and has already drunk a great deal of water should not be given more; call emergency services (Hew-Butler and colleagues, 2015).

Examining people the way they run

Walther, author of the foundational AK textbooks, set out the principle of examining patients in the way they live and play sport (Synopsis, p. 219), and the clinic follows that principle. Leaf, in the 1984 proceedings of the International College of Applied Kinesiology (ICAK), tested the muscles of a marathon runner before a training run and after miles 5, 8, 12 and 16 (1 mile is about 1.6 km), and noted that after only 3–4 minutes on a treadmill, the quadriceps (the front of the thigh) could become clearly weak even though testing lying down was still normal. The clinic does not test muscles on a treadmill; patients walk, run and jump right at the clinic and are then retested.

The sequence of the examination combines Walther and Cuthbert. The doctor asks whether it hurts when you stand, when you walk or only when you run, and looks at where your shoe soles are worn and where the calluses are on the soles of your feet. Next comes testing muscles “in the clear”, that is, testing each muscle on its own while the patient lies still, and then retesting it under load. The gait test checks pairs of shoulder and hip muscles on opposite sides at the same time: if each group is strong on its own but weak when tested together, the test is positive, and there is often a foot joint out of place that needs to be mobilized. Then come the search for reactive muscles, the ligament stretch reaction, repeated muscle testing and a foot examination, and finally the patient walks, runs and jumps and is examined again right away.

A knee that gives way when you change direction, with normal scans

Trail runners often say that at a sharp turn or a tilted rock, the knee or ankle suddenly gives way, yet the muscle examination and X-rays are both normal. AK calls this the picture of a reactive muscle: the muscle is strong when tested lying down, but lets go at the very moment the joint needs its support. In the lower limb, two muscles that are often reactive are the gastrocnemius (calf muscle) and the popliteus, which lies behind the knee (Walther, Synopsis, p. 77, 218–219). After an inversion ankle sprain, the medial head of the gastrocnemius may stay shortened and painful even after the tissue has healed. The doctor treats it right in the session with strain/counterstrain, that is, holding the leg in one position for about 30 seconds so the muscle lets go.

For the inner knee there is another possibility: the ligament stretch reaction, in which a muscle that was strong becomes weak right after the examiner stretches a ligament of the related joint. A common cause, according to Walther, is whole-body stress loading onto the adrenal glands (small glands sitting on top of the kidneys that help the body cope with stress); it is also seen in perfectionists and people used to pushing through. People with this reaction get injured easily when running or twisting, and training to exhaustion makes it worse. The muscles AK links to the adrenals include the sartorius, gracilis, gastrocnemius, soleus and tibialis posterior (Synopsis, p. 212–213, 523–526), which is exactly the inner knee, the calf and the arch of the foot.

Training hard and sleeping little before race day

Once it is clear which muscle has switched off, the doctor asks why. In runners, the answer may be stress, an old injury, or something the body is short of, such as iron, sodium, potassium or a vitamin. A later article in the series will go into each of these; for nutrients, see the two sections below.

The adrenal glands take stress from many sources, including the workplace, a home with chemical exposure, emotional issues, and the type of person who pushes themselves to train hard while sleeping very little (Synopsis, p. 527). That last one sounds like a description of a race preparation season. To find out whether emotions are involved, the patient places one hand on the emotional reflex point on the forehead and the other on the adrenal reflex point, and the muscle is retested; this is called two-handed therapy localization. If the muscle changes strength at that moment, emotions are pushing the gland off balance (same page).

For people who are overtraining, sleeping poorly or under heavy pressure before a race, the clinic uses an in-depth AK technique to check for stress in the frontal lobe, limbic system and cingulate gyrus, brain areas involved in regulating emotions under pressure. This way of checking comes from the clinic’s own clinical experience. The doctor locates the area of stress using therapy localization and challenge (applying a light stimulus to a joint and seeing how the muscle changes), corrects it right in the session, and then retests the muscles around the knee to see whether they change too.

Inner knee pain with the pelvic bone shifted backward may clear up completely after treating the muscles, mobilizing the pelvis and having the patient chew suitable nutrients, but it tends to come back as long as adrenal function has not returned to normal (Synopsis, p. 476–477).

So when the whole adrenal muscle group named in the previous section tests weak together, the doctor asks further about sleep, training schedule and race season, and orders lab tests when needed.

Old injuries, the most consistent predictor mentioned at the start of this article, are read by AK from the side of the nervous system. Walther puts the Injury Recall Technique (IRT) at the head of the chapter on basic examination techniques, because while an old injury still leaves its imprint, the patient may respond to treatment but the results may not last (Synopsis, p. 196). For a sprain on the trail, a fall or an old surgical scar, the clinic uses IRT and P-DTR (Proprioceptive Deep Tendon Reflex, a technique that corrects the signals from the sensory receptors in muscles, tendons and joints) so the nervous system receives accurate information again.

Ten muscle tests and one ferritin test

Runners need muscles that last for hours, not just strength in a single test. Goodheart, the founder of AK, devised repeated muscle testing: slow-twitch muscles (muscles built for long, steady work) are tested about 10 times in 10 seconds, and the weakness often shows up partway through the series. When only one muscle weakens progressively with this kind of testing, Walther notes that it often needs a source of iron; he cites cases with low ferritin (a measure of the iron stored in the body) while hemoglobin (the measure used to tell whether you are anemic) was still normal (Synopsis, p. 200–201).

At the clinic, repeated muscle testing is a hint for the doctor to order a ferritin test. If you really are low, iron is supplemented based on the lab results, because muscle testing is not used to set doses.

Unevenly worn soles and a short calf

In the Synopsis, the foot is ranked as the second structural cause of poor coordination by the nervous system (neurologic disorganization), after only the craniosacral system, that is, the skull and the sacrum at the base of the spine (p. 461–465). The foot rolling in (the arch dropping and the ankle tipping slightly inward) as it lands is necessary. The trouble comes when it does not stiffen in time to push the body forward, which is called prolonged pronation. The doctor tests a muscle while the patient stands, then has them turn the foot outward; if the muscle becomes strong again, prolonged pronation is suspected.

A common cause is a short triceps surae, the calf group that attaches to the Achilles tendon. The goal is for the foot to bend upward by at least 10 degrees. The talus in these feet is almost always out of position and is mobilized during the session. At home, the patient stretches the calf with a contract–relax–stretch method (tense the calf, let it go, then stretch it), 5 times a day; after 30 days the foot bends upward about 6 degrees more, according to figures Walther recorded. Shoes should be firm, low-heeled and laced snugly. Orthotic insoles that are too rigid actually do harm.

The handful of supplements in your running pack

Runners often take magnesium, zinc, collagen, electrolyte tablets and iron all at once. The clinic checks each one using the standard method Walther described in 1981 (Basic Procedures, p. 45–50):

• The patient drinks plain water first, because dehydration skews the results;
• The doctor chooses a specific muscle and tests it first;
• The patient tastes a small amount of the substance being tested, holding it in the mouth without swallowing, or sometimes only smells it;
• The doctor retests that same muscle: a weak muscle becoming strong means the substance suits you, a strong muscle becoming weak means it does not;
• No testing by holding the bottle in your hand, because Walther classes this method as a questionable procedure.

In runners, AK authors pay attention first to sodium and potassium: if salt makes a muscle weak, potassium often makes it strong, and vice versa. Maffetone (ICAK proceedings, 1983) describes a runner who put a little salt in his mouth at mile 5, after which his running form went back to how it had been in the first mile.

This way of checking helps find what the body is short of even when lab results are within normal limits. It goes alongside lab tests, not in place of them: iron deficiency needs ferritin, hyponatremia needs a sodium measurement, rhabdomyolysis (muscle breaking down on a large scale) needs a CK muscle enzyme test, and a suspected stress fracture needs MRI; Walther himself wrote the same (Synopsis, p. 171). Runners in races with doping control have all the more reason to show their handful of supplements to the doctor. Of 634 supplement products surveyed, about 15% contained banned substances not listed on the label (Geyer and colleagues, 2008). Stark, an AK author, advises using only products with NSF certification (the mark of an independent testing organization in the United States); certification lowers the risk but does not remove it completely (Maughan and colleagues, 2018).

Treat, then run again

In AK, diagnosis and correction go hand in hand. The two core tools are therapy localization, mentioned above (the patient places their own hand on the suspect area and the muscle is retested), and challenge (applying a light stimulus to a joint and seeing how the muscle changes).

Reactive muscles in the calf and behind the knee are treated with strain/counterstrain, as described. The pelvis and spine are mobilized directly, or with SOT (Sacro Occipital Technique) using blocks (wedge-shaped pads placed under the pelvis). The fascia around the painful area is treated with fascial release (a technique that releases the connective tissue covering the muscles). IRT and P-DTR are used for signals still distorted by old injuries, as described, while the NeuroLymphatic and NeuroVascular reflex points are used for muscles that have tested weak.

After treatment, the doctor has the patient walk, run and jump, then immediately retests the muscles that were weak, to see whether the correction holds under load.

The 50 ml pouches after the examination

The Su Wen (素问 / 素問, Basic Questions) has the line “prolonged walking injures the sinews” (久行伤筋 / 久行傷筋, jiǔ xíng shāng jīn): walking too long harms the sinews, that is, the tendons and muscles. The line is understood as a reminder: training until you are tired is fine, but don’t go as far as exhaustion. Muscle cramps are called “vop be” by people in southern Vietnam; an old text notes that when both blood and qi are scant, cramps and pain under the heel are common (Basic Theory of Chinese Medicine, 中医基础理论 / 中醫基礎理論, p. 459).

After the AK examination and the four examinations (the four ways traditional medicine examines: looking, listening and smelling, asking, and taking the pulse), the doctor may prescribe a decoction in ready-to-drink 50 ml pouches, cooked in a separate batch for each person, according to the traditional medicine pattern:

• Long-lasting fatigue and slow recovery after a race or a heavy training block: qi and blood deficiency (气血虚 / 氣血虛, qì xuè xū; the body is short of both strength and nourishment), and a complete blood count and ferritin are required first;
• Heavy sweating, thirst and shortness of breath after a hot running season: dual deficiency of qi and yin (气阴两虚 / 氣陰兩虛, qì yīn liǎng xū; both strength and body fluids are depleted); the pouches cannot replace rehydration and electrolytes;
• Recurring calf cramps: Liver blood deficiency with the sinews undernourished (肝血虚、筋失养 / 肝血虛、筋失養, gān xuè xū, jīn shī yǎng; the blood of the Liver is too scant to nourish the tendons and muscles), after low potassium, low sodium and drug-induced cramps have been ruled out;
• Aching back and knees in middle-aged runners, or recovery from a diagnosed low-risk stress fracture: Liver and Kidney deficiency (肝肾虚 / 肝腎虛, gān shèn xū; the Liver and Kidney are weak, so tendons and bones are poorly nourished);
• Swelling and bruising after a fall or an ankle sprain on the trail, once a fracture has been ruled out: blood stasis (血瘀, xuè yū; bruised blood that circulates poorly), used only for a short course.

Some herbs, such as Niu xi (Achyranthes bidentata root), Dan shen (Salvia miltiorrhiza root), San qi (Panax notoginseng root) and Hong hua (Carthamus tinctorius flower), are not used during pregnancy or while trying to conceive. When you are trying to conceive, you are prescribed a version that keeps Du zhong (Eucommia ulmoides bark) and Sang ji sheng (Taxillus chinensis stem and leaf), two herbs the materia medica books record as “calming the fetus” (安胎, ān tāi). Pregnant people can still have an AK examination; the doctor just does not test the pelvic muscles once the pregnancy is advanced, and the clinic does not use acupuncture needles during pregnancy.

As for evidence, only Danggui Buxue Tang (当归补血汤 / 當歸補血湯, Chinese Angelica Blood-Supplementing Decoction) has been tested in runners: in one small trial in 36 male recreational runners, the group taking it finished faster in a 13 km run, and this has not been repeated (Chang and colleagues, 2018). The other approaches rest on the classics and case series. The clinic does not promise that the pouches will make you run faster; they go together with reducing load and guided retraining. A formula containing Huang qi (Astragalus membranaceus root) or Wu wei zi (Schisandra chinensis fruit) should not be taken within 2 hours before a run in the heat or before a race.

Runners in races with doping control need to tell the doctor in advance. Higenamine is on the 2026 Prohibited List of the World Anti-Doping Agency (WADA) and is banned at all times, both in and out of competition. It has been measured in Lian zi xin (Nelumbo nucifera plumule), Huang bai (Phellodendron bark), Wu zhu yu (Tetradium ruticarpum fruit) and Xi xin (Asarum root and rhizome), and detected in Hou po (Magnolia officinalis bark), Sheng ma (Cimicifuga rhizome), Huang lian (Coptis rhizome), Xin yi (Magnolia flower bud) and Suan zao ren (Ziziphus jujuba var. spinosa seed) (Lin and Hsu, 2024; Sakamoto, 2025). There are no data yet on human urine after drinking a decoction, so all we can say is that these herbs may cause a positive test. For now these herbs have no substitutes, so competitors stop taking the medicine at least one day before race day; runners should still read the rules of their own race.

Back on the same stretch of road

Back to the unevenly worn shoes in the corner. Once all the signs that call for imaging have been screened out, a normal scan is good news; it just doesn’t answer why the pain comes back at that same distance. Usually the answer lies in a muscle that switches off right when the joint needs it, and on that question, the worn-down heel of the shoe tells more than the scan.

If you are caught in that cycle of resting, running and hurting again, bring your running shoes to the appointment. Dr. Dinh Ngoc Duc (MD, MSc in Traditional Medicine) will examine you while you stand still, then examine you again right after you run. Book a consultation.

Worth keeping

• Pain at one point on a bone that keeps getting worse, hip pain when bearing weight, dark urine after running: stop running and get checked first;
• Write down your weekly distance, where it hurts and at which kilometer the pain starts, over the last few weeks;
• Bring the running shoes you are using and your watch or running app to the appointment;
• Bring all the supplements and medicines you are taking, including cold medicines, rubbing ointments and Chinese herbal medicines;
• Wear clothes you can run in, because the doctor will have you walk, run and jump and then examine you again;
• If muscle testing suggests low iron, have a ferritin test before taking iron;
• If your race has doping control, tell the doctor before anything is prescribed.

References

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