Objective Musculo-skeletal Measurement Protocols
A clinician needs objective documentation of both the diagnostic and treatment results for musculo-skeletal dysfunctions. Muscles can be assessed as either subgroups of myotatic units, as subgroups of neuro-innervation or, in measurement terms, as bilateral homologous contra-lateral data. SEMG allows the development of protocols that corresponds with each of the above. Whether testing is done by myotatic units engaging one or more joints or by neuromuscular innervation that may affect several joints, bilateral testing can be done through the relevant range of motion (ROM) and intervening rest periods. ROM is typically composed of numerous motion segments, each having different muscle action/interactions. For example, the ROM of the wrist joint, which utilizes seven muscles for motion, can be broken down into four segments: wrist extension, flexion, ulnar and radial deviation.
The protocols, developed by the author, basically stipulate a five-time repetition of any given segment of ROM activity for seven seconds interspersed with two seconds of rest intervals. The five repetitions allow for more accurate statistical data gathering and for determination of internal consistency and reproducibility along the muscles simultaneously tested. Since range of motion, primary movers, and neuromuscular innervation are all universally known and accepted, these protocols of SEMG testing are based on clinically accepted data.
These protocols aim for overall standardization of the SEMG procedure, similar to the standardization that occurred in the 1920s for the EKG procedure. The author has published database test results on 6,700 individual muscles, representing about 173 skeletal muscles investigated through 22 protocols. This database allows any clinician or investigator to compare individual findings on a given patient with those of the corresponding normalized database values.
The remaining sections will explore general results and implications of these benchmark protocols utilizing the wrist joint ROM as an example. Appendix A describes the corresponding wrist ROM SEMG testing, statistical data for functional inter-muscular and inter-segmental motion relationships of the myotatic unit under asymptomatic conditions.
Muscular Agonism/Antagonism Revisited
The concept of muscular agonism (synergism) and antagonism has not been questioned throughout the modern era of medicine. One tends to use these words almost indiscriminately to define a functional relationship among various muscles or segments of motion, usually within the same myotatic unit, but sometimes among muscles subtending different joints. The closest anatomical definition may relate to the actual position of a given muscle on a bone and joint. One tends to describe muscles positioned on opposite sides of a bone/ joint as “antagonists" and muscles positioned on the same side of a bone/ joint as “agonists or synergists.” The concept may further imply that one muscle may move the joint in one direction, e.g. wrist flexion, while the other may be “inhibited” during such motion and the corollary may apply to the opposite motion, e.g. wrist extension. Until now, there has been no actual study available to demonstrate this functional relationship. Indeed, the concept applies poorly to segments of motion that are neither flexion nor extension as, for example, in the case of the wrist ulnar and radial deviation.
The advent of the ability to test skeletal muscles with SEMG allowed for statistical analysis of objectively-derived electrical amplitude data through the different segments of motion of a given joint in both asymptomatic or symptomatic conditions. Thus, in the case of the wrist joint, one can simultaneously test the primary wrist joint muscles, i.e. the flexor and extensor carpi radialis and ulnaris, pronator teres and quadratus as well as the supinator through the segmental motions of wrist extension, flexion, ulnar and radial deviation.
In the specific example of wrist ROM, SEMG dynamic test protocols of the activity potentials of the myotatic unit of the wrist have been used to define the muscular relationships of agonism and antagonism. The values of the correlation coefficients of the different muscles, computed through the wrist ROM segments served to establish positive or negative relationships among the wrist muscles. Such testing was conducted for the wrist joint ROM as well as all the other major joints.
The amplitude potentials data of each of these muscles through the wrist joint ROM (in asymptomatic muscles or symptomatic muscles) could then be compared to those of the other muscles of the myotatic unit in terms of statistics of correlation coefficients (r).
The comparisons result in correlation data which are either positive or negative, according to the tendency of any muscle to become more or less active through a given segment of motion, especially in comparison with its neighbors from the same myotatic unit. Such data could then be translated in terms of correlational relationships of muscular agonism (synergism) or antagonism. The positive correlation coefficients represent muscular synergism or agonism. Negative correlation coefficients represent muscular antagonism.
Thus, the old concept of agonism and antagonism — never before tested scientificall — could be verified with the new technology. In a number of cases, the old assumptions were found to hold, in a number of other cases they did not. The correlation coefficients among the muscles tested through each major joint ROM have been calculated and published in a number of textbooks and articles.1,2, 3, 4
SEMG studies have shown that symptomatic muscles presenting with loss of strength and pain generally show high levels of amplitude potentials both at rest and during motion.
Diagnosis of Symptomatic Muscle
SEMG studies have shown that symptomatic muscles presenting with loss of strength and pain generally show high levels of amplitude potentials both at rest and during motion. This has been shown to be the case in over 500 different muscles from various parts of the body, including the hand and wrist.1,5 When treated statistically in comparison with non-symptomatic muscles, those dysfunctional muscles show greater than 25% higher amplitude potentials both at rest and during any segment of motion. Physiology dictates that muscles that are overworking and utilizing more energy than normal may fatigue earlier. Fatigue itself can promote both pain and general weakness and secondary deconditioning. Thus, if a clinician finds SEMG-derived amplitude potentials abnormally high at rest and during different segments of a given primary joint ROM, the dysfunctional relationship between that muscle and other muscles in its primary myotatic unit may be objectively measured. The SEMG data would then clearly identify the muscle(s) requiring rehabilitation, including pain management and SEMG/biofeedback. Resulting symptomatic improvement, manifested by the muscle no longer presenting weakness or pain, should coincide with SEMG resting and activity potentials returning to the expected range.1,6 In terms of the wrist joint muscles, normalization of such values would be compatible with lack of symptoms and normal wrist/hand strength.2,7