Testing Knee Strength at Home
Strength testing at home may seem daunting, but I promise that it’s actually simple once you get a few reps in.
We’ll go over the setup, instructions for testing, and provide links to the equipment we’ve used for our own at-home setups.
Find a stable chair or platform that you can sit on that allows your feet to be off of the ground.
Pass your bite strap through the U-shaped bracket on the crane scale
Loop a bite strap around an immovable object (a post, column, leg of a bed with the chair touching the frame, etc)
Loop another bite strap through a carabiner and then around your ankle. It should be snug, but not painful. Feel free to put a small towel between the strap and the front of your ankle if testing causes discomfort. If you want to purchase a dedicated ankle strap, you can here, but it is not necessary.
Attach the carabiner to the crane scale
Turn on the crane scale
Make sure you are measuring in the correct unit (pounds, kilograms, etc)
Check to make sure the unit reads 0 lbs/kg. Hold the zero button down if it does not.
Press the hold button until the word “Hold” appears. From now on, the peak number will be displayed
Sit on the platform and pull the strap between the scale and immovable object until your knee is at a perfect 90 degree angle when you press into the ankle strap.
Sit tall, cross your arms across your chest and try to straighten your leg. You should have a pain rating of 3 out of 10 or less. Anything higher means you need to reduce effort for now. If you are strong enough to lift your thighs off of the seat, you may need one more strap wrapped around the chair and your thighs like a seat belt to keep you down.
Do 3 repetitions on each leg. If your number keeps improving, feel free to do additional reps until you no longer achieve a higher number. It’s advisable to wait at least 1 minute after each rep.
Unhook the ankle strap and move your seat a few feet away from where your scale is attached.
Sit down facing the scale and reattach the ankle strap.
Make sure your knee is at a 90 degree angle
Repeat steps 11 through 13, but attempt to bend your knee instead of straightening.
Record your numbers for all movements on each leg
In a calculator, enter your unaffected leg straightening number, press the division symbol (/ or ÷), enter your affected leg straightening number, then press enter or =, then multiply (x) 100. This number is the percentage of your strength symmetry for Knee Extension (straightening) strength, often referred to as quad strength symmetry.
Repeat step 18 for your knee bending numbers. This number is the percentage of your strength symmetry for Knee Flexion (bending) strength, often referred to as hamstring strength symmetry.
Repeat this process at regular intervals to hold yourself and your sports medicine team accountable for your progress.
