History of the Study of Skeletal Muscle Function with Emphasis on Kinesiological Electromyography

Abstract

Study of muscles started probably when someone tried to understand how he can move from A to B and executes movements at will. Knowledge was always dependent on the technology available to conduct investigation. Religious belief had a negative impact on muscle study when interfering with dissection of human corpse. During the Italian Renaissance (end of XIV th to beginning of XVI th century), study of muscles was first descriptive, based on dissection. Artists like Leonardo da Vinci (1452-1519) and Michael Angelo (1475-1564) exaggerated the bulk of muscles. Their first concern was the influence of the volume of the superficial muscle on the surface modelling represented in their paintings and sculptures. Leonardo da Vinci multiplied the number of bundles of some muscles. Most of his representations of tendon insertions are imprecise. Leonardo da Vinci applied mechanical principles to rib, elbow kinematics and kinetics of the foot. Vesalius (1514-1574) was a medical doctor and an anatomist. His anatomical plates are remarkable because they respect most of the relationships between muscles. Then Galileo (1564-1642), Borelli (1608- 1679) and Newton (1642-1727) thought that physics and mechanical laws governed motility of animal and human body alike. Incidental discovery of electro stimulation effect on muscle in Galvani's laboratory and electric current concomitant of muscles contraction by Matteucci and Du Bois Reymond were major breakthroughs. Recording of this current was the starting point for ECG, EMG and EEG. ECG entered first in the clinic. EMG and EEG waited for cathode ray oscilloscope. The Voltaic Pile and faradic current opened the door of electrical stimulation to Duchenne de Boulogne (1806-1875). Matteucci's (1811-1868) publications inspired and stimulated Du Bois Reymond. Du Bois Reymond (1818-1889) repeated and completed his experiments on frogs. He designed a very sensitive galvanometer with which he recorded his own global EMG. EMG remained a curiosity of laboratory until Erlander (1874- 1965) and his pupil Gasser (1888-1963) improved the cathode ray oscilloscope for electrophysiological recordings. A combination of orthopaedic surgeons, engineers and physiologists in Berkeley (1945) systematically recorded EMG during gait of normal man. EMG biofeedback and phonomyography have also raised interest by clinicians. Their EMG signals processing in the time domain (full wave rectification miscalled integrated EMG) was later completed in the early '80s by computation of the root mean square on personal computers. Despite all factors minimizing the reliability of analysis based on amplitude of the EMG signals, these methods still represent the clinician's routine tool today. Since 1999, researchers have proven the benefits of muscular intensity analysis, time frequency analysis, mapping of spatio temporal activity. We deplore that the corresponding software is not available for clinicians. Multivariate methods of statistics allow the comparison of EMG patterns under pathological condition and can be helpful in differential diagnosis.