Isometric Leg Strength Tests

by Shawn Keith

About Shawn Keith

Shawn Keith began is freelance writing career in 2010, with articles published on LIVESTRONG.COM. He has worked in the health/fitness field since 1997. Prior to getting into personal training, he worked in cardiac rehabilitation and hospital wellness facilities. Keith is certified in posture analysis by GMP Fitness. He earned is Bachelor of Science in exercise science from Missouri Western State University.


The American Council on Exercise defines an isometric muscle action as one in which your muscle exerts force but does not change in length. The isometric leg strength test measures the strength of your legs and back. The test requires a strength dynamometer and a cable tensiometer.

Testing Procedure

Reset the dial on the dynamometer to zero prior to beginning the test. Stand upright on the platform of the dynamometer with your feet shoulder width-apart. Your arms hang straight down, allowing you to hold the center of the bar with both hands. Your palms face toward your body. Adjust the chain until your knees bend to about 110 degrees. Your back bends slightly forward at your hips. Hold your head upright and look straight ahead. Keeping your arms straight and without bending your back, pull as hard as possible on the chain. Keep your feet flat on the platform and pull in a smooth and steady manner.

Using the Data

Med-Tox Health Services recommends performing three trials of the test, using the average of your last two attempts as your score. The results show the maximum amount of force your legs can apply. This information allows you to determine your appropriate starting point for your exercise program. Subsequent test scores show your progress during your training program. In the workplace, employers use this data in choosing workers for physically demanding jobs.

Advantages and Disadvantages

According to the American Council on Exercise, isometric strength testing is the most accurate method in assessing actual muscular strength. The simplicity of the test is another advantage. The ability to only test one person at a time is a drawback. The necessary equipment is not readily available. An elevated blood pressure response during the test is also a disadvantage of this test.


The leg extension strength test is a variation on the isometric leg strength test. You need a table and a specially constructed box with two arm supports, connected to a screen for this test. Sit on the table between the arm supports with your lower legs hanging down, your knees at 90-degree angle. A shin guard attached to a resistance is fastened around your right lower leg. Extend your right knee by raising you right lower leg with maximum strength and hold that position for 3 seconds. You may lean on the arm supports during the test. Avoid explosively raising your lower leg. After one practice attempt, the best score of your three attempts is recorded. Rest about 30 seconds between each attempt.

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This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or