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This is a procedure in which a body part, for example an extremity, is placed into a position as to approximate the origin and insertion of the muscle to be tested. This is usually the position of maximum contraction of the muscle to be tested. The body parts are positioned so to best isolate the muscle from its synergists.
After adequately stabilizing the patient, a contact is made by the examiner using the fleshy portion of the hand. This contact is placed against the distal portion of the body part, avoiding as much as possible any bony contacts. The patient is instructed to maximally contract the muscle in the vector that isolates the muscle. This pressure is resisted by the examiner, who thus keeps the test isometric, until the examiner detects no more increase of force against his/her hand. As this point an additional, slowly increasing small force is exerted at a tangent to the arc created by the body part being tested. |
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The initial increase of force up to the patient's maximum voluntary strength should not exceed 1.5 seconds; the increase of pressure applied by the examiner should not exceed 1 second duration. A strong muscle is defined as one which is able to adapt to the additional force and maintain its contraction with no weakening effect. A weak muscle as regarding to this test is defined as one that cannot actively contract enough to reach the testing position or, when in the proper position, adapt to the slight increase in presure; the muscle then suddenly and characteristically fails completely to contract against the examiner's pressure. |