The purpose of resistance muscle testing, whether performed manually or by a machine, is to determine the extent of muscular weakness as the result of an injury, disease or disuse. Anti-gravity resistive muscle testing was first developed by Dr. Robert Lovett, Professor of Orthopedic Surgery at Harvard Medical School, in 1912.
Principle of Resistive Testing
The principle of resistive muscle testing to isolate each muscle of your body according to its individual function and apply a resistive force against the muscle as it moves your limb against gravity. Dr. Lovett developed procedures for resistively testing each individual muscle (the human body has approximately 639 muscles). For instance, to test the strength of your bicep muscle, which bends your elbow, the tester would place one hand on your shoulder to stabilize your body, then the other hand on your wrist and attempt to straighten your bent elbow as you resist this.
Grading Interpretation of Resistive Muscle Tests
If you are unable to totally resist his effort to straighten your elbow, then the tester can assign a grade to determine the strength of your muscle. When performing resistive muscle testing, five possible grades can be assigned to determine the strength of the muscle. Three main grades are fair plus, good and normal. A fair plus grade indicates the muscle can withstand only a minimal amount of pressure, good equates to moderate pressure withstood and a grade of normal is indicative of normal muscle strength.
When Resistive Testing Cannot Be Done
Circumstances exist in which resistive muscle testing cannot be performed. That is when the muscle is unable to resist any limb movement against gravity. Under these circumstances, the muscle would be determined to be weak and a rehabilitation program would be initiated to restore the strength and function of the muscle.
Grading Scale for Non-resistive Tests
The grading scale for non-resistive testing includes seven grades that are assigned to determine how weak your muscle is. The main, non-resistive grades are fair, poor, trace and zero. A fair grade is indicative of your ability to only lift your limb against gravity alone, without resistance. A grade of poor means you are unable to move your limb against gravity. Limb movement is only possible if gravity is eliminated. A trace grade means that a slight muscle contraction is felt and a grade of zero means there is no muscle movement at all.
Testing Precautions or Risks
The tester providing the resistive muscle testing must be cautious if you have thin bones, possible fractures, bone infection, limited ability to ward off infections due to chemotherapy or a tumor, fatigue easily, pain with testing, or a poor cardiovascular status. Also, if you have had a recent surgery or abdominal herniation, your tester should avoid these areas as well.
References
- Muscle Testing, Techniques of Manual Examination Third Edition; Daniels and Worthinghan; 1972
- Encyccloopedia Entry: Muscle Testing
