Six in the morning, two people sit on the steps of the ward community hall, shoes still on. You and a woman from your office agreed to take up running at the start of the month, four laps around the neighborhood every morning on the brick-paved sidewalk. By the third week, both of you complain of shin pain. She pulls up her trouser leg and runs a finger along the inner edge of the bone, toward the back, over a stretch about the length of a hand in the lower half of the leg. You point to the front, slightly to the outside of the edge of the bone, right where the muscle bulges each time you pull the tip of your foot up toward you.
In the running group, both pains go by the same English name: shin splints, meaning shin pain from running. In fact, on each side of the lower leg there is a different muscle doing more than it can handle, and Applied Kinesiology (AK, a way of testing the strength of each muscle by hand to read the state of the body) also links each muscle to a different place in the body. So the two people on the steps may need two different lines of search for the cause.
The shinbone and “growing pains”
When we were small and our shins ached at night, grandmother would say it was “growing pains” and that a good night’s sleep would make them go away. Adults who take up running are no longer growing. A shin that aches after a few weeks of training is a matter of load: the leg is being asked to do more than it has the strength for at that point.
Cuthbert, in his Applied Kinesiology book on the lower body, considers the term “shin splints” to be used far too broadly. He keeps it for a narrow meaning: pain in the muscles and tendons of the group that flexes or extends the foot, caused by repetitive running on hard surfaces, once stress fractures (small cracks in the bone from repeated loading) and a lack of blood supply to the muscle have been ruled out. The spot that is most tender to pressure is usually where the muscle attaches to the bone lining, on the front or the back of the lower leg (p. 241–242). This kind of pain tends to come in the first weeks of a training season (p. 244). The two people on the steps are right in that stretch.
Pain along the inner edge, like your colleague’s, is what the medical literature now calls medial tibial stress syndrome (MTSS). The review by Kakouris and colleagues (2021) puts it at about 9.4 % of new injuries in runners. Your pain at the front and outside belongs to the front muscle group.
Pain in one exact spot means stop running
Before talking about muscles, one question needs asking. Does the pain spread along a stretch, or is it focused on one point? A stress fracture hurts in one exact spot, hurts when that spot is pressed, gets worse session after session, and sometimes hurts even at rest or lying in bed at night (Joyce and Lewindon, 2016; Magee and Manske). With pain like that, stop running and see a doctor; what scans to do is for the doctor to decide.
Cuthbert adds two features on examination. In a stress fracture, the pain lies in the bone itself; touching the surface of the bone around that spot is very painful, and there may be swelling and warmth. To tell the two apart, he looks at what makes the pain worse. If contracting the muscle, as during muscle testing, makes it hurt more, that points toward the muscle and tendon; if putting weight on the leg makes it hurt more, think of the bone (p. 243).
The front of the shinbone needs special attention. The anterior tibial cortex, the layer of hard bone at the front of the shin, is among the stress fracture sites that heal poorly and need follow-up by a specialist (Joyce and Lewindon, 2016).
There is one situation that cannot wait for an appointment. If after a blow the lower leg becomes tight and hard very quickly, goes numb, and the pulse is weak, those are signs of acute compartment syndrome: the muscle swells inside a closed compartment of the lower leg and squeezes the blood vessels and nerves. Go to the emergency department right away, and do not raise the leg (Travell and Simons; Magee and Manske).
The muscle that brakes the foot, at the front and outside
The tibialis anterior attaches along the upper two thirds of the outer surface of the shinbone, then runs down to the inner side of the top of the foot. It pulls the tip of the foot up and tilts the foot inward (Cuthbert, p. 25).
Each time the heel strikes the ground, this muscle, together with the toe extensors, brakes the front of the foot so that it lowers gradually instead of slapping onto the road. The harder the heel strike and the harder the surface, the more the muscle has to brace. Normally it gets to rest in the middle of the phase when the foot is on the ground. When it has to brace through that phase too, the muscle works for almost the whole stride cycle and becomes inflamed easily. The front compartment of the lower leg is also a closed space, so swelling fluid drains poorly, and the runner feels a tight ache (Cuthbert, p. 242).
Four laps of brick sidewalk every morning, landing heel first, is exactly the kind of surface and stride that makes this muscle brake the most. And training usually leaves the front muscle group weaker than the back group (p. 242). An overly tight calf limits how far the ankle can bend upward and, according to Maffetone (an AK author and endurance coach), may also inhibit the tibialis anterior on testing (cited in Cuthbert, p. 27).
The inner edge, where the tibialis posterior holds up the arch
The tibialis posterior lies deepest in the back compartment of the lower leg. It attaches to the back of the shinbone and the fibula; its tendon curves behind the inner ankle bone and attaches to the navicular (a small bone in the middle of the inner edge of the foot, just in front of the inner ankle bone) and to many bones on the sole of the foot (Cuthbert, p. 27). This muscle holds up the inner long arch when you walk and run, keeps the two ankle bones hugging the talus firmly, and is needed every time you rise onto your toes (p. 28–29, 244).
From just after the heel strikes the ground until just before the heel lifts, the work belongs to the whole back muscle group: the tibialis posterior, the soleus and the two toe flexors. During that stretch the foot pronates, meaning the arch lowers and the ankle rolls inward, to absorb the force, and then it has to rise back up in time. If it rises back slowly, the back group is overloaded. The tibialis posterior carries the heaviest load, because at the same time it both holds up the arch and steadies the ankle joint (Cuthbert, p. 242). On the same page, Cuthbert cites Michael and Holder, who found that the attachment of the soleus becomes an area of stress when the heel tips outward, because the inner part of the soleus tries to pull the heel back.
The two problems easily become tangled. When the tibialis posterior is working below threshold, meaning it tests weak, the foot pronates more (p. 244), and a foot that pronates more puts even more load on the tibialis posterior. Maffetone adds that when the tibialis posterior is inhibited, the calf and the soleus (the muscle lying under the calf) tighten up in response, and this chain can cause pain at the back of the lower leg (cited in Cuthbert, p. 28, 244).
Insoles, exercises and brick pavement
For MTSS along the inner edge, no treatment clearly beats any other in the review by Teles and colleagues (2026). A randomized trial in 40 recreational runners by Naderi’s group (2025) also found that adding lower-leg exercises to treatment did not reduce pain more. Prevention is clearer. Neuromuscular training programs (training the nerves to control the muscles faster and more skillfully) and anti-pronation insoles work, shock-absorbing insoles do not, and static stretching (stretching and then holding still for a while) has no evidence yet that it prevents MTSS; that is the result of the meta-analysis by Marques and colleagues (2025).
An anti-pronation insole supports exactly the arch that the tibialis posterior has to hold up. Connecting those two points is our own reading; no study has done it. For pain at the front and outside, we have not yet found a dedicated trial in the literature available.
For the two people on the brick sidewalk, a new pair of shoes or an added slope also counts as more load, even if four laps are still four laps (Joyce and Lewindon, 2016). Cuthbert advises against forcing a stretch on the muscles in a compartment that is painful, because it usually makes things worse (p. 243). Anyone who has had to stop should return by Sahrmann’s milestone: walk 30 minutes with no increase in pain before mixing in running, on soft surfaces first.
The bladder, the adrenals and two muscles in the lower leg
In the AK muscle chart, these two muscles go two different ways. Walther, author of the AK textbook series, pairs the tibialis anterior with the bladder, with vitamin A as the nutrient that often goes with it (Synopsis, p. 330), and the tibialis posterior with the adrenal glands, and possibly the bladder as well (p. 331). The link only shows the doctor where to test next. Sometimes the bladder has a disorder and the tibialis anterior still tests strong. So Ramsak and Gerz have the patient place their own hand on the point Zhongji (Conception Vessel 3), the front-mu point of the bladder, meaning the point on the abdomen where the qi of the bladder gathers, and then test a strong muscle (cited in Cuthbert, p. 27).
Cuthbert is brief about the tibialis anterior. This muscle often goes with shin splints; testing it is then often painful, and after treatment the pain during testing drops markedly (p. 26). He cites the blinded study (information hidden from the person measuring so the result is not swayed) by Perot and colleagues (1991) on this very muscle in ten people: the electrical activity of the muscle changed in line with the “strong” or “weak” result the examiner recorded, and not because the examiner pushed harder or more gently (p. 26).
The adrenal link of the tibialis posterior takes a detour through the foot. Walther notes that prolonged pronation of the foot is common in people with adrenal stress, perhaps because the tibialis posterior is both linked to this gland and steadies the ankle (Synopsis, p. 515). In people with pain at the back of the lower leg, Cuthbert often finds signs on the tibialis posterior such as a muscle stretch reaction (the muscle weakens right after being stretched gently) and the neurolymphatic reflex point of the adrenals, that is, the reflex point AK uses to test this gland (p. 244). When the tibialis posterior is weak because the adrenal glands are overloaded, he advises planning a longer course of treatment (p. 29). A crowded training season with little sleep is when the clinic asks about this part in detail.
One examination for two shins
Before any step, Cuthbert sets one condition: no treatment until a lack of blood supply to the muscle and a stress fracture have been ruled out (p. 243). So the doctor runs a hand along the front of the shinbone, feeling for one exact tender spot on the surface of the bone. He also advises examining the patient when they have just been active enough for the pain to show (p. 243), so there is no need to wait until the shin has settled completely before coming in.
You lie on your back first, for the tibialis anterior. You pull the tip of your foot up and tilt it inward, with your toes curled. The doctor places a hand on the inner side of the top of your foot, pushes gently in the opposite direction and watches the tendon stand out (Cuthbert, p. 25). When the tibialis anterior falls short, people often lift their toes to borrow strength from the toe extensors (p. 25).
Then it is your colleague’s turn, with the tibialis posterior. The foot is pointed fully, then tilted inward, toes still curled, and the doctor pushes the inner edge of the foot outward (p. 27–28). This muscle sometimes only shows itself when tested several times in a row. In people with lower-leg pain, repeated muscle testing of the tibialis posterior is often positive, meaning the muscle weakens after a few tests (p. 242). Bandy also saw many athletes whose tibialis posterior tested strong the first time, and only fell short when the muscle was stretched once and then retested (cited in Cuthbert, p. 244).
If her tibialis posterior falls short, the foot is checked first. The doctor applies a light, directed pressure to each joint of the foot and then retests the muscle; AK calls this a challenge. The direction that makes the tibialis posterior strong again, most often a navicular that has dropped, shows that joint is the root, and it is mobilized first. Cuthbert notes that while the joint is still out of place, strengthening the muscle by other means does not hold: as soon as the patient walks, the muscle weakens again (p. 28).
For your tibialis anterior, the doctor checks whether your calf is too tight and asks about old ankle sprains. Ankle sprains, sloping roads and rough tracks can all leave tender points in the muscle (p. 27). Vitamin A, the nutrient Walther places next to the tibialis anterior, may be tasted in a small amount while the muscle is retested. When the adrenals or the bladder are suspected, you place your own hand on the matching reflex point while the doctor tests; AK calls this step therapy localization.
Treatment follows exactly what was just found. The doctor mobilizes the foot joints in the direction found on challenge, re-stimulates the signals in the muscle, taps tendon reflexes according to Palomar’s P-DTR (Proprioceptive Deep Tendon Reflex, a technique that uses tendon reflexes to correct the sensory signals sent from muscles and joints to the brain), and stimulates the neurolymphatic reflex point of the linked organ, all with gentle movements and no stretching. Then both muscles are retested. The tibialis posterior is tested once more after she stands up and walks, because that is when it often weakens again. A muscle getting stronger when a substance is tasted is only a hint; whether to take a supplement is decided after looking at lab tests and how you eat.
The shin in the medical classics
Traditional medicine places the muscles and the four limbs under the Spleen: “the Spleen governs the flesh and the four limbs” (脾主肌肉、四肢, pí zhǔ jī ròu, sì zhī). The Spleen here is a traditional medicine concept, tied to digestion, absorption and nourishing the muscles. The traditional healer (lương y) Nguyen Huu Duc distinguished the form and the qi of the Spleen right at the calf. Whether the calf is full or wasted is the physical form of the Spleen (脾形, pí xíng), while its strength is the Spleen qi (脾气 / 脾氣, pí qì). When teaching about the Kidney, the organ that “governs the two feet” (主两足 / 主兩足, zhǔ liǎng zú), the healer also mentioned pain along the inner side of the shinbone; placing that remark next to MTSS is our own inference.
Some people new to running eat poorly, stay tired long after a session and look pale. Once a complete blood count and ferritin (a measure of the iron stored in the body) are back, the doctor may prescribe a decoction in ready-to-drink 50 ml pouches for the pattern of qi and blood deficiency (气血虚 / 氣血虛, qì xuè xū), meaning the body is short of both strength and the blood that nourishes it, as traditional medicine sees it. The base formula is Danggui Buxue Tang (当归补血汤 / 當歸補血湯, Chinese Angelica Blood-Supplementing Decoction: five parts Huang qi (Astragalus membranaceus root) to one part Dang gui (Angelica sinensis root)), combined with Si Jun Zi Tang (四君子汤 / 四君子湯, Four Gentlemen Decoction) to supplement Spleen qi. If you are low in iron, iron is supplemented based on the lab results; the pouches cannot replace that, and the shin still needs its load increased gradually.
When to see a doctor
Pain in one exact spot on the bone, especially on the front of the shinbone, needs to be seen right away. A lower leg that quickly turns tight and hard and goes numb after a blow means going to the emergency department. Apart from those two cases, book an appointment when spread-out shin pain has lasted two or three weeks and cutting back the load has not helped, when the pain comes back every time a new training season starts, or when pain along the inner edge comes with a pronating foot and a fallen arch.
The two people on the community hall steps may well go home with two different sets of advice. Your colleague may need her foot and tibialis posterior looked at; for you, it is the calf and the tibialis anterior. At the clinic, Dr. Dinh Ngoc Duc (MD, MSc in Traditional Medicine) tests both muscles on both legs of each person before talking about when to return to the sidewalk. Book a consultation.
Worth keeping
- Run a finger along your shin: pain spread along a stretch is different from pain in one exact spot; pain in one spot on the bone, especially on the front of the shinbone, means stop running and see a doctor;
- A lower leg that quickly becomes tight and hard and goes numb after a blow means going to the emergency department; do not raise the leg;
- New shoes, a new road surface or added slopes all count as more load; change only one thing at a time;
- Do not force a stretch on the part of the lower leg that hurts;
- With pain at the front and outside, notice whether your calf is too tight, and tell the doctor about old ankle sprains;
- With pain along the inner edge and a fallen arch, ask the doctor about anti-pronation insoles and an examination of the tibialis posterior.
References
Sources in Vietnamese
- Nguyễn Hữu Đức. Bài giảng Tạng Thận. T10.
- Nguyễn Hữu Đức. Bài giảng Tạng Tỳ. T7.
Sources in English
- Cuthbert S. 2013. Applied Kinesiology: Clinical Techniques for Lower Body Dysfunctions. Gangasas. p. 25–29, 241–244.
- Joyce D, Lewindon D, editors. 2016. Sports Injury Prevention and Rehabilitation: Integrating Medicine and Science for Performance Solutions. London: Routledge. p. 213, 229–230, 232, Table 16.1.
- Kakouris N, Yener N, Fong DTP. 2021. A systematic review of running-related musculoskeletal injuries in runners. J Sport Health Sci. 10(5):513-522. doi:10.1016/j.jshs.2021.04.001. PMID: 33862272.
- Magee DJ, Manske RC. 2021. Orthopedic Physical Assessment. 7th ed. St. Louis (MO): Elsevier. p. 1270, 1333, 1377, Table 13.16.
- Marques TBT, Rangel RPS, Martins LV, Vidal APC. 2025. Preventive interventions for medial tibial stress syndrome: Systematic review and meta-analysis. Gait Posture. 122:92-98. doi:10.1016/j.gaitpost.2025.07.312. PMID: 40633262.
- Naderi A, Fallah Mohammadi M, Heidaralizadeh A, Moen MH. 2025. Effects of Integrating Lower-Leg Exercises Into a Multimodal Therapeutic Approach on Medial Tibial Stress Syndrome Management Among Recreational Runners: A Randomized Controlled Study. Orthop J Sports Med. 13(2):23259671241311849. doi:10.1177/23259671241311849. PMID: 39958697.
- Palomar Lever J. Proprioceptive-Deep Tendon Reflex (P-DTR) [introductory brochure]. p. 13–17.
- Perot C, Meldener R, Goubel F. 1991. Objective measurement of proprioceptive technique consequences on muscular maximal voluntary contraction during manual muscle testing. Agressologie. 32(10 Spec No):471-4. PMID: 1844106 (Cited in Cuthbert, p. 26).
- Sahrmann S, et al. 2011. Movement System Impairment Syndromes of the Extremities, Cervical and Thoracic Spines. St. Louis (MO): Elsevier Mosby. p. 392–393, Box 7-1.
- Teles AI, da Silva Carto JP, Parpa K, Thuany M, de Vasconcelos GS. 2026. Load-induced medial leg pain in runners: A systematic review of non-invasive treatment approaches. Phys Ther Sport. 81:101962. doi:10.1016/j.ptsp.2026.101962. PMID: 42462658.
- Travell JG, Simons DG. 1992. Myofascial Pain and Dysfunction: The Trigger Point Manual. Vol. 2: The Lower Extremities. Baltimore (MD): Williams & Wilkins. p. 380, 461.
- Walther DS. 2000. Applied Kinesiology: Synopsis. 2nd ed. Pueblo (CO): Systems DC. p. 330–331, 515.
Sources in Chinese
- 李冀, 连建伟, 主编. 方剂学. 第 174 页.
- 王新华, 主编. 中医药学高级丛书 · 中医基础理论. 第 219、225、239、402、413 页.
