Isometric Muscle Testing
Isometric muscle testing is commonly performed by doctors and therapists to test your strength and determine whether an injury or illness has affected it. Although it is used by medical professionals, isometric muscle testing, also called manual muscle testing, is a relatively simple task and can be performed by nonmedical personnel as well. You can use it with a partner to test your strength and determine whether your workout routine is effectively helping you to get stronger.
When testing a patient's muscles during an isometric contraction, the limb must be completely still while being resisted. Hand placement is also vital so that the results will be more accurate. Place one hand above the joint being tested and one hand below it. If possible, place the hand that is on the far end of the joint as far away from the joint as possible, without crossing over another joint. For example, when testing elbow strength, place one hand across the biceps in the upper arm and one hand just above the wrist.
Position the distal hand, or the one that is farther from the body, along the side of the limb so that you can resist the movement of the muscle you are testing. For example, to test the knee joint, place both hands on the back of the leg for flexion (bending) or on the front of the leg for extension (straightening).
Make sure that the person being tested is relaxed and is not able to move any other joints to help with the movement of the joint being tested. For example, when testing the elbow, make sure your arm placed along the bicep holds the upper arm steady so that the shoulder cannot participate and invalidate your results.
Try These Exercises!
Instruct the person being tested to try to move her limb against the resistance you are providing. Try to hold the limb completely steady and resisting for up to five seconds. Many different strength test scales are available; however, the majority of therapists, doctors and nurses are taught to use a 5-point scale. Most people will likely score a 3 to 5 on the scale. A score of 3 indicates that the limb can move through the full normal range. A strength score of 4 shows that the limb is able to withstand moderate resistance. The highest score of 5 would be used for anyone who can resist the maximum amount of resistance.
Limitations of the Test
Because each individual has a unique amount of strength, what one tester may consider "maximum" resistance may only be equal to "moderate" resistance provided by another tester. Because of this inconsistency, isometric muscle testing provides a general range rather than an exact measure of strength. Detailed and exact strength tests require specialized equipment and meters as well as training in how to use these devices correctly.
- Occupational Therapy; Elizabeth Blesedell Crepeau et al.
- Encyclopedia of Medical Devices and Instrumentation; W.K. Durfee and P.A. Laizzo
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