Yinshi

What is ST33?

ST33 (Yinshi) is a Stomach-channel point on the front of the thigh, about three thumb-widths above the top outer corner of the kneecap.

Its Chinese name, Yinshi, is usually translated as "Yin Market". In classical and modern Chinese medicine it is treated as a local point for the knee and the front of the thigh, and it is grouped with the nearby Stomach points used for leg pain, stiffness and weakness. Tradition also links it with knees that feel cold or numb.

ST33 is taught in most acupuncture curricula, but it is a secondary point. Practitioners reach far more often for ST34 and ST35 around the knee, so ST33 tends to appear as a supporting point rather than a headline one.

Here is the honest verdict on the evidence: there is no human research that tests ST33 on its own for any condition. What exists are trials of multi-point acupuncture or acupressure sessions for knee osteoarthritis and leg pain, where ST33 may or may not be one of several points used. Those studies cannot tell you what this single point does. Short-term relief that people report after pressing a sore thigh muscle may simply be the effect of warmth, touch and attention, all of which are real but are not specific to ST33.

Two things are worth saying clearly once, and they apply to this whole page. First, a long traditional record is not evidence that a point produces a particular effect in the body. Second, a long traditional record is not evidence that pressing it is safe for you, because the classics were not written with modern conditions such as blood clots or recent joint surgery in mind.

Used sensibly, self-applied finger pressure here is a low-risk comfort measure on a large muscle. Treat it as that, not as a treatment for a diagnosed knee or nerve problem.

Where is ST33 and how do you find it?

ST33 sits on the front of the thigh, roughly three thumb-widths above the upper outer corner of the kneecap, in the muscle just outside the midline.

• Sit with the knee bent. Sit on a chair with your foot flat on the floor and the knee bent to about a right angle. This makes the kneecap and the thigh muscles easy to feel.
• Find the top outer corner of the kneecap. Run a fingertip up the kneecap until you reach its flat upper edge, then slide to the outer (little-toe side) corner. That corner is your starting landmark.
• Measure three thumb-widths up. Classical texts place ST33 three cun above the upper border of the patella (kneecap). Three cun is about the width of your own four fingers held together, or roughly 6 to 7 cm on an average adult.
• Stay on the line to the hip bone. The point lies on a line drawn from that top outer kneecap corner up towards the bony knob at the front of your hip (the one you feel when you push your hands onto your hip bones).
• Confirm with muscle, not bone. You should be in soft muscle on the outer part of the front thigh, not on the hard shaft of the thigh bone further round the side. A gentle squeeze often finds a slightly firmer or tender band.

A simple cross-check used by many teachers: stretch your arm down your thigh with the hand flat and fingers together. ST33 falls close to where the tip of the middle finger lands on the outer front of the thigh.

Do not worry about millimetre accuracy. This is a large muscular area, and self-applied pressure spreads over a broad patch anyway. If one spot feels distinctly more tender than its neighbours, work there.

How do you apply pressure to ST33?

1. Settle and support the leg. Sit with the knee bent and the foot flat, or lie down with a pillow under the knee. A relaxed thigh muscle is much easier to work on than a braced one.
2. Locate and anchor. Place the pad of your thumb or two fingertips on the point, three thumb-widths above the top outer corner of the kneecap. Use the pad, never a fingernail.
3. Press in slowly. Sink in over three to five seconds until you feel a firm, dull ache. Aim for about four or five out of ten on a discomfort scale. Sharp, burning or shooting sensations mean stop and move off.
4. Hold or circle. Hold steady for 30 to 60 seconds, or make small slow circles for the same time. Breathe normally; do not hold your breath against the pressure.
5. Release and repeat. Ease off over a few seconds, rest for about 30 seconds, then repeat two or three times. Two to three minutes per thigh is plenty.
6. Work both legs. Even if only one knee bothers you, doing both sides keeps things balanced and takes under five minutes.
7. Repeat sensibly. Once or twice a day is a reasonable rhythm. There is no evidence that more frequent or harder pressure does more good.

Because ST33 lies on thick thigh muscle, some people prefer a loose fist or the heel of the hand to a thumb. That is fine. Keep the pressure broad and slow rather than digging with a point.

Stop straight away if pressure causes numbness, pins and needles travelling down the leg, pain that lingers after you let go, or new swelling. Mild tenderness for an hour afterwards is common and settles. Do not press through a bruise you have just created, and give the area a day off if it is sore the next morning.

What is ST33 traditionally used for?

• Knee pain and stiffness. This is the main traditional use: ST33 is a local point for the front of the knee and thigh. Human evidence is indirect. Trials of acupuncture and acupressure for knee osteoarthritis (wear-related knee arthritis) show modest short-term pain relief in some studies, but those sessions use several points and rarely single out ST33, so nothing can be credited to this point alone.
• Cold or numb feeling in the knee and leg. Classical texts describe Yinshi for knees that feel cold, heavy or numb. No human study has tested this. Warmth and improved comfort from rubbing a large muscle are expected from touch itself, whichever point you choose.
• Weakness or heaviness of the leg. Tradition lists ST33 among points for motor difficulty in the lower limb, including after stroke. Research on acupuncture in stroke rehabilitation is mixed and mostly uses whole-body protocols with needles. There is no acupressure evidence for ST33 and recovery of leg strength, and self-pressure is not a substitute for physiotherapy.
• Thigh muscle tightness after activity. A popular modern use is on the quadriceps after walking, cycling or standing all day. This is really self-massage of a tight muscle, which many people find eases soreness briefly. Studies of massage for muscle soreness are small and short-term, and the effect fades.
• Lower back and leg aching. Some texts extend ST33 to aching that runs from the low back into the thigh. There is no trial support. Pain that shoots down the leg from the back needs a proper assessment rather than finger pressure.

The honest summary: ST33 has a clear traditional role around the knee and thigh, and essentially no direct human evidence of its own. Expect, at most, temporary comfort from pressure on a tight muscle.

Are there tips for using ST33 effectively?

• Warm the muscle first. A few minutes of walking, or a warm shower, makes the quadriceps softer and the pressure more comfortable. Working a cold, tight thigh usually just feels bruising.
• Hunt for the tender spot. Press a small area around the three thumb-widths mark and settle on whichever point feels most tender in a dull, satisfying way. That is more useful than chasing an exact measurement.
• Use a broad contact. On a big muscle like this, the heel of the hand or a loose fist spreads load better than a thumb tip and saves your thumb joints if you do this often.
• Pair it with movement. Many people get more out of pressing while slowly straightening and bending the knee a few times. Gentle movement with pressure often eases stiffness more than static holding.
• Keep sessions short and regular. Two or three minutes once or twice a day beats one long, heavy session. Hard, prolonged digging mostly produces bruising.
• Track whether it actually helps you. Note your knee or thigh comfort before and an hour after, for a week. If nothing changes, drop it rather than adding more pressure.
• Do not use it to push through pain. If pressing lets you ignore a knee that hurts when you walk, that is a reason to get the knee looked at, not a reason to press harder.
• Keep it as an add-on. It sits alongside quadriceps strengthening, weight management and whatever your clinician has advised, all of which have far better support for knee problems than any acupressure point.

One practical note for older readers or anyone with thin skin: use lighter pressure and shorter holds, and check the skin afterwards for marking. Comfort is the goal, and more force does not buy more benefit.

What do people get wrong with ST33?

• Expecting a cure. The commonest error is treating ST33 as a fix for arthritis, a meniscus tear or nerve damage. No acupressure point repairs joint or nerve tissue, and any relief is likely to be brief.
• Confusing it with its neighbours. ST34 (Liangqiu) sits about two thumb-widths above the kneecap and ST32 (Futu) about six. People often press one of those and call it ST33. On a thigh this size the practical difference is small, but it is worth knowing which point you actually found.
• Measuring from the wrong edge. The three thumb-widths are counted from the upper border of the kneecap, not from the middle of it or from the knee crease behind. Starting low puts you well off the mark.
• Pressing on the thigh bone. Drifting too far round the outside of the thigh lands you on hard bone. ST33 is in soft muscle on the front-outer thigh.
• Grinding with a fingernail. Nails break skin and leave scratches on a muscle that needs broad, slow pressure. Use finger pads or the heel of the hand.
• Treating pain that travels. Pressing the thigh for pain that shoots from the back or buttock down the leg delays assessment of a possible nerve problem. Get it checked.
• Working a swollen, hot leg. Some people massage a swollen calf or thigh hoping to shift it. That is exactly the situation where a blood clot must be ruled out first.
• Overdoing the pressure. Leaving bruises is a sign of too much force, not of a thorough session. Firm but tolerable is the target.

A final one: dropping prescribed exercises because the point feels nicer. Quadriceps strengthening has real evidence behind it for knee pain. Finger pressure does not replace it.

What does the research on ST33 actually say?

There is no published human trial that tests ST33 on its own, for any condition, in either needling or acupressure form. That is the plain answer, and it is the same answer for most individual acupuncture points outside a small handful such as PC6 for nausea.

What does exist sits one step removed. Acupuncture has been studied fairly extensively for knee osteoarthritis (wear-related knee arthritis), including large randomised trials and systematic reviews. Those studies generally report small to modest short-term improvements in pain and function, with much of the difference from sham treatment being small and debated. Crucially, the point prescriptions in that work centre on points around the knee joint itself and on the lower leg, not on ST33. Where ST33 appears at all, it is one of several points in a package, and a package cannot tell you what a single point contributes.

Acupressure research on knee and leg pain is thinner again. The trials are mostly small, unblinded and short-term, often comparing pressure with no treatment rather than with a convincing sham. That design reliably favours the active group, because touch, warmth, time and expectation all produce measurable relief. Results from such studies should be read as encouraging but weak.

So the honest position for this page is: insufficient human evidence for ST33 specifically. That does not mean pressing it is pointless or harmful. It means any benefit you notice is most plausibly explained by general effects of self-massage on a large thigh muscle, plus the natural ups and downs of musculoskeletal pain, rather than by something unique to this location.

If you see a video claiming ST33 clears knee arthritis or restores leg strength, no study supports that claim. Nothing on this page should be read as a citation for a named trial of ST33, because none was found.