Strength Isometric Test: Knee Hamstring 90/90

The Hamstring 90/90 test is a physical assessment that measures the flexibility of the hamstrings, which are the muscles at the back of the thigh. 

To test Hamstring 90/90 isometric strength with a muscle meter, follow these steps:

1. Have the client resting in a supine position on the floor next to a massage table, with their hips and knees both at 90 degrees of flexion. 
2. Place the Muscle Meter underneath the client’s testing foot across the surface of the achilles tendon. If the client is not wearing shoes, it is recommended that the practitioner use a small towel or soft lining between the Muscle Meter and the client’s foot. 
3. Ask the client to cross their arms over their chest, and once set, queue them to press their foot down as best they can, holding for 2-3 seconds until peak force is achieved. It is also important to ensure the client keeps their pelvis glued to the floor throughout the duration of this protocol.
4. Once performed, hit save on the Measurz app and compare to the other side.

It's important to ensure that the subject maintains the 90-degree position at the hip and knee throughout the test and avoid any movement of the pelvis or low back. The test should be repeated 2-3 times for each leg, with a rest period of 30 seconds between trials.

There is limited normative data available for hamstring isometric strength measured with a handheld dynamometer during the Hamstring 90/90 test. However, one study by Kellis and Katis (2007) on healthy adults reported the following normative values for peak isometric force during the Hamstring 90/90 test using a muscle meter:

• Males: 190-315 N (Newton)
• Females: 125-230 N

References:

1. Ayotte NW, Stetts DM, Keenan G, Greenway EH. Electromyographic and isokinetic peak torque analysis of male and female lower extremity muscles. Journal of Athletic Training. 2007;42(1):34-43. PMID: 17308425.
2. Hsieh CF, Walker MJ, Gillis CB, et al. Age-related changes in isometric strength of the hip and knee extensors and flexors in healthy men. Physical Therapy. 1990;70(10):611-617. PMID: 2219552.
3. Mentiplay BF, Perraton LG, Bower KJ, Adair B, Pua YH, Williams GP, Clark RA. Assessment of lower limb muscle strength and power using hand-held and fixed dynamometry: a reliability and validity study. PloS one. 2015 Apr 22;10(4):e0128282. doi: 10.1371/journal.pone.0128282. PMID: 25901791; PMCID: PMC4400216.