The Weizhong (BL-40), also known as the Supporting Middle, is a powerful acupressure point located on the back of the knee, at the midpoint of the transverse crease of the popliteal fossa. It’s nestled between the tendons of the biceps femoris and semitendinosus muscles.
In Traditional Chinese Medicine (TCM), this point belongs to the Bladder meridian and is recognized for its ability to clear heat, benefit the lumbar region and knees, and activate the meridian to alleviate pain.
Quick benefits at a glance:
- Eases lower back pain and sciatica
- Alleviates knee pain, leg stiffness, and lumbar strain
- Assists with herniated discs, arthritis, and hypertension
Alternate names for BL-40 include “Middle of the Crook” or simply “Bladder 40,” used in some modern acupressure and acupuncture literature.
Summary Table
| Attribute | Details |
|---|---|
| Pressure Point Name | Weizhong – BL-40 (Supporting Middle) |
| Body Area | Back of knee |
| Exact Location | Center of the crease behind the knee, between the biceps femoris and semitendinosus tendons |
| Common Uses | Lower back pain, sciatica, knee arthritis, lumbar muscle strain, hypertension |
| Stimulation Technique | Apply firm thumb pressure for 1–3 minutes with the knee slightly bent |
| Contraindications | Avoid on open wounds or swollen knees; use caution with severe varicose veins or during pregnancy |
Clinical Significance & Associated Conditions
BL-40 plays a central role in treating musculoskeletal and neurological disorders. It is frequently used to alleviate:
- Sciatic nerve pain
- Lumbago
- Stiffness in the legs
- Knee joint pain from arthritis
- Hypertonicity of the hamstrings
Energetically, Weizhong is a He-Sea point on the Bladder meridian, meaning it regulates qi flow from deeper body levels. It’s also categorized as the “Command Point of the Back,” making it essential in treating conditions related to the spine and lumbar region.
Location
To locate BL-40:
- Sit or lie down with the leg slightly flexed.
- Find the crease at the back of the knee.
- Press gently at the midpoint between the inner and outer tendons—you’ll feel a soft depression right in the middle.
Looking for an easier way to use this point in your wellness routine?
This pressure point is simple to locate and even easier to apply when guided step-by-step. It’s featured in over 70 evidence-based pressure point protocols inside our Pressure Points Guide app. Whether you’re looking to relieve lower back pain, ease sciatica, or reduce knee inflammation, the app guides you through every session with visuals and audio. Click here to download our app
How to Stimulate It
- Tool: Use your thumb or index finger.
- Posture: Seated with the knee bent slightly.
- Pressure: Moderate to firm, pressing straight into the crease.
- Duration: 1 to 3 minutes per side.
- Frequency: Once or twice daily, especially after physical activity.
- Optional pairing: Combine with BL 23 – Sea of Vitality for enhanced back relief.
Benefits and Common Uses
BL-40 is widely used in both clinical and home acupressure for:
- Acute and chronic lower back pain
- Herniated lumbar discs
- Sciatica and nerve entrapment
- Knee osteoarthritis and joint stiffness
- Hypertension and heat syndromes
- Leg fatigue and heaviness
In energetic terms, it clears “blood stasis” and “damp-heat” from the lower body, which TCM associates with pain, inflammation, and fluid retention.
Physiological Functions & Mechanisms
BL-40 influences:
- The Bladder and Kidney meridians, key players in water metabolism and lower body vitality.
- The sciatic nerve, due to its proximity to nerve branches running through the posterior leg.
- Vascular and muscular systems can be improved by improving circulation in the popliteal region and reducing pressure on compressed tissues.
Stimulation of this point may help modulate pain signals and encourage neuromuscular relaxation.
Practitioner Insight
I often recommend Weizhong to clients who sit for long hours or have lumbar tightness that won’t respond to a general massage. When paired with gentle stretching or breathwork, this point helps soften the lower back and release stubborn energy blocks in the legs.
Safety & Contraindications
- Avoid stimulating this point if the popliteal area is swollen, infected, or bruised.
- Do not apply strong pressure if there are severe varicose veins or vascular issues.
- Use caution in pregnancy, especially when treating the lumbar area.
- For complete safety guidelines, refer to our acupressure safety guide and browse more insights on acupressure here.
As always, listen to your body and stop if discomfort arises.
Related Points & Techniques
For synergistic effects, combine BL-40 with:
Support techniques include slow diaphragmatic breathing, heat therapy, and postural alignment exercises.
💡 More sessions with Weizhong (Supporting Middle) (BL-40) in our “Pressure Points Guide App”
Access guided sessions
Scientific Perspective
Studies in complementary medicine support the use of BL-40 for lumbar disc herniation, with evidence pointing to reduced pain sensitivity and improved physical function after stimulation. Some trials also suggest benefits for hypertension management, likely due to its regulatory effect on autonomic tone and circulation.