Yingu

What is KI10?

KI10, or Yingu, sits in the crease behind the knee, at its inner end between two tendons you can feel when the knee bends.

Its Chinese name, Yingu, is usually translated as "Yin Valley," a reference to the soft hollow between those two tendons on the inner side of the leg. In traditional Chinese medicine it is the he-sea point of the Kidney channel and the channel's water point, which gives it a settled, well-documented place in the classical system.

Classical texts link KI10 to urinary and genital complaints, to pain on the inner knee and thigh, and to patterns the tradition calls Kidney deficiency. Those are traditional categories, not diagnoses in the modern medical sense, and they do not map neatly onto anything a doctor would test for.

Here is the honest verdict on the evidence, and it applies to everything else on this page. A point's long history in the tradition is not evidence that pressing it does anything, and it is not evidence that pressing it is safe. For KI10 specifically, we could not find controlled human trials that tested this point on its own for any condition. That places it at the low end of the evidence scale, even though it ranks high in traditional standing.

There is one practical reason to read the safety section before you press anything. KI10 lies at the edge of the popliteal fossa, the soft hollow behind the knee, and that hollow carries the main artery, vein and nerve of the leg. A swollen, hot or tender calf or knee can be a sign of a blood clot, and firm pressure there is a genuinely bad idea.

Everything described in this library is self-applied finger pressure. Nothing here involves needles, heat, cupping or anything that breaks the skin.

Where is KI10 and how do you find it?

KI10 is at the inner end of the crease behind your knee, in the gap between the two tendons you feel there when you bend your knee.

• Sit and bend the knee. Sit on a chair or the floor with the knee bent to roughly a right angle. The tendons only stand out when the knee is flexed, so a straight leg makes the point hard to find.
• Find the back-of-knee crease. Run a fingertip along the horizontal fold behind your knee. This fold is your main landmark.
• Travel to the inner end. Slide along that crease towards the inside of the leg, the side nearest your other knee.
• Feel for two cords. Near the inner end you should feel two firm tendons running up the back of the thigh, side by side. Pressing your heel gently into the floor makes them pop out.
• Drop into the gap. KI10 sits in the soft hollow between those two tendons, right on the level of the crease. It usually feels slightly tender or spongy compared with the firm cords either side.

Classical texts place KI10 on the medial end of the popliteal crease (the inner end of the fold behind the knee), between the tendons of semitendinosus and semimembranosus — two of the hamstring tendons. In practical terms, that is about one to two thumb-widths in from the inner edge of the knee crease, depending on the size of your leg.

If you cannot tell the two tendons apart, do not guess your way towards the middle of the crease. The centre of that hollow is a different point and sits directly over the big artery and nerve. Stay at the inner end, on the tendon side, where you can feel firm cords under your fingers.

How do you apply pressure to KI10?

1. Get the knee bent and supported. Sit with your foot flat on the floor or your ankle resting on the opposite knee. A bent knee brings the tendons up and takes slack off the area.
2. Reach around with the same-side hand. Cup your hand around the back of the knee so your thumb or index finger lands in the hollow at the inner end of the crease.
3. Check for a pulse first. Rest the finger pad there for a few seconds. If you feel a clear throbbing under your fingertip, you are over a vessel. Move slightly towards the inner edge, or stop.
4. Press with the flat of the finger. Use the pad, never a nail or a knuckle. Build pressure slowly over two or three seconds.
5. Keep it moderate. Aim for a firm, dull ache you would rate about 3 or 4 out of 10. Sharp pain, pins and needles, or anything shooting down the calf means ease off immediately.
6. Hold or circle for 30 to 60 seconds. Either hold steady or make small slow circles. Breathe normally rather than holding your breath.
7. Release and repeat. Let go slowly, rest 20 seconds, and repeat up to three times per side. Twice a day is plenty.

Stop the session altogether if the knee becomes more painful, if the area goes numb, if the leg feels weak when you stand, or if you see redness or swelling afterwards. Do not press through pain in the hope of a bigger effect; firmer is not better here, and the structures behind the knee do not reward force.

Finger pressure only. Do not use massage guns, hard tools or elbows in the hollow behind the knee, and never try to break the skin.

What is KI10 traditionally used for?

• Urinary difficulty. Classical sources name KI10 for painful, slow or dribbling urination and for retention. There are no controlled human trials of acupressure at KI10 for urinary symptoms, so this remains a traditional claim only. New or worsening urinary problems need a medical assessment, not a pressure point.
• Genital and reproductive complaints. Texts list it for impotence, genital pain and itching, and for irregular or prolonged uterine bleeding. Evidence is absent. Heavy or unexplained bleeding is always a reason to see a clinician.
• Inner knee and thigh pain. The point sits in a region that often aches with hamstring tightness or inner-knee strain, and tradition uses it for pain along the inner leg. Acupressure for musculoskeletal pain in general has small, mostly unblinded trials behind it, with modest short-term results; none of that work isolates KI10.
• "Kidney deficiency" patterns. As the water point of the Kidney channel, KI10 is used in the tradition for tiredness, low back ache and cold limbs grouped under that heading. These are traditional categories rather than medical diagnoses, and no human study has tested the point against them.
• General relaxation. Many people find slow, steady pressure on a tender spot calming. That is a plausible and harmless use, though the effect is likely from the pause, the touch and the breathing rather than anything specific to KI10.

Put simply: the traditional indication list for KI10 is long and the human evidence list is empty. Treat it as something that may feel pleasant and may form part of a self-care routine, not as a treatment for a urinary, reproductive or knee condition. If symptoms in any of those areas are new, severe or getting worse, get them looked at properly first.

Are there tips for using KI10 effectively?

• Bend the knee to roughly 90 degrees. The two tendons that frame KI10 only stand up when the knee is flexed. With the leg straight, the hollow flattens and you will almost certainly land in the wrong spot.
• Press your heel down to raise the cords. Gently pushing your heel into the floor tightens the hamstring tendons so you can feel the gap between them clearly, then relax before you press.
• Warm the area first. A few minutes of walking or a warm shower makes the tissue behind the knee softer and the landmarks easier to feel.
• Use the thumb pad, not the tip. A broad, flat contact spreads the load. A fingertip or nail digs into a crowded area that has nerves and vessels running through it.
• Work both legs. KI10 is a paired point, one on each knee. Treating both sides keeps the routine balanced and takes the same couple of minutes.
• Keep sessions short and regular. Two or three 30 to 60 second holds, once or twice a day, is more sustainable than one long hard session.
• Note what actually happens. Jot down what you pressed and how you felt an hour later. Over a couple of weeks this tells you far more than any claim on a video.
• Check your skin afterwards. Bruising or lingering soreness means you used too much force. Reduce the pressure next time rather than stopping altogether.
• Pair it with the rest of your care. If you are already doing knee rehab exercises or taking prescribed medicine, acupressure sits alongside those. It does not replace them.

One more practical point: comfort matters. If reaching behind your own knee strains your back or hip, sit with the ankle crossed over the opposite thigh so the back of the knee comes to you.

What do people get wrong with KI10?

• Expecting a cure. The commonest error is treating KI10 as a fix for a urinary, fertility or knee problem. No acupressure point cures anything, and nothing here is guaranteed to change a symptom.
• Drifting to the middle of the crease. The centre of the hollow behind the knee is a different point and lies over the main artery and nerve of the leg. KI10 is at the inner end, between two firm tendons.
• Searching with the leg straight. With the knee extended the tendons disappear and the whole area feels the same. Bend the knee before you look.
• Pressing far too hard. People assume deeper means stronger. Behind the knee, heavy pressure just bruises soft tissue and can irritate a nerve.
• Using a tool or massage gun. Hard implements concentrate force into a hollow that is already crowded with vessels. Fingers only.
• Ignoring a swollen, hot calf. Rubbing a painful swollen lower leg is genuinely risky, because it can be a clot. That symptom needs a doctor the same day, not pressure.
• Pressing straight after knee surgery or injury. Fresh stitches, a recent knee replacement or a new injury mean the area is off limits until your surgeon or physiotherapist clears it.
• Confusing tenderness with correctness. A sore spot is not proof you found KI10. Hamstring tendons are often tender on their own.
• Dropping prescribed treatment. Some people trial acupressure instead of their medication for bladder or prostate symptoms. Stopping prescribed treatment without medical advice is the one mistake on this list that can do real harm.

If you are unsure whether you have the right spot, the safest default is to stay on the inner side, use light pressure, and stop if anything feels sharp, tingling or pulsing.

What does the research on KI10 actually say?

We could not find useful human research testing KI10 on its own, by acupressure or any other method, for any condition. That is the honest answer, and it is the answer for most individual acupressure points.

What exists in the wider literature does not fill the gap. KI10 occasionally appears inside multi-point acupuncture protocols in trials of urinary symptoms, menstrual problems or knee pain, but in those studies several points are needled at once. When a protocol uses six or eight points together, nothing in the result can be attributed to any single one of them. Those trials also test needling by a practitioner, not finger pressure applied by the reader, and the two are not interchangeable.

It is also worth knowing how weak the acupressure evidence base is generally. Most trials are small, run for a short time, and cannot blind participants, because a person always knows whether someone is pressing on them. That combination tends to inflate reported benefit, especially for outcomes measured by self-report such as pain or fatigue. Where acupressure has been studied more carefully across many trials, as with PC6 on the forearm for nausea and vomiting, the evidence is reasonably convincing. KI10 has nothing resembling that body of work behind it.

So the practical reading is this. KI10 has a solid position in the traditional system, as the he-sea and water point of the Kidney channel, and that position is well documented in classical and modern teaching texts. It has essentially no modern human evidence of its own. Gentle self-applied pressure on a tender spot behind the inner knee is low-cost and, for most people, low-risk. It is not a treatment for a urinary, reproductive or knee condition, and it should not delay a proper assessment of symptoms in any of those areas.