# Knee and Ligament Strength

How the knee hinges, how the ACL, PCL, MCL and LCL ligaments hold it steady, and how squats and soft landings protect it\.

By bright\-dolphin\-8c4809de

Topic: Human Body & Medicine

[Open the interactive Jig](https://ask.jig.com/j/0JFGO6w2N6ab)

## Transcript

### 1. Meet your knee

Your knee is where your thigh bone, the femur, meets your shin bone, the tibia\. It is the biggest joint in your body and it carries you every time you walk, run or jump\. Let's discover how to keep it strong\.

### 2. A hinge that rolls and glides

The knee mostly bends like a door hinge, from straight to about 135 degrees\. The rounded end of the femur rolls and glides over the flat top of the tibia\. Try bending it yourself\.

Smooth, slippery cartilage covers the bone ends so they glide easily\.

### 3. Ligaments: living ropes

Ligaments are tough, stringy bands that tie bone to bone\. The MCL runs down the inner side of the knee and the LCL down the outer side\. Together they stop the knee bending sideways\.

### 4. The cross inside

Deep inside the knee, two more ligaments cross like an X\. The ACL stops the shin sliding forward, and the PCL stops it sliding back\. Press the button to give the shin a forward tug and watch the ACL hold it\.

The ACL is only about 3 cm long, yet it can hold a pull of about 2,000 newtons, like the weight of 200 kg\.

### 5. Muscles are bodyguards

Ligaments grow stronger only very slowly, but muscles get stronger in a few weeks\. The quadriceps on the front of the thigh straighten the knee\. The hamstrings on the back bend it and pull the shin back, helping the ACL\.

### 6. Squats build strength

Slow squats, lunges and bridges strengthen the quadriceps, the hamstrings and the hip muscles\. Strong muscles share the load, so the ligaments do less work\. Press the button for a slow squat\.

Children build the same strength by climbing, hopping, skipping and playing\.

### 7. Keep knees over toes

When a landing wobbles, the knee can cave inward\. That twist strains the ACL and MCL, and many knee injuries happen this way without bumping into anyone\. Balancing on one leg and strong hip muscles help the knee stay in line\.

### 8. Land like a cat

Land softly on the balls of your feet with your knees bent and pointing over your toes\. Bent knees let the muscles soak up the landing\. Press the button to see a soft landing\.

Warm\-ups that mix strength, balance and landing practice cut ACL injuries by about half in some sports teams\.

### 9. Build up a little at a time

Warm up first, add a little more each week and rest between hard days\. Muscles, tendons and ligaments all toughen with steady, regular use\. If your knee hurts or swells, ask a doctor or physiotherapist\.

This is general information, not medical advice\.