Firing frequency of single motor units upon voluntary control of the isometric tension in human muscles.
Selective surface electrodes were used to study 120 motor units (MUs) from m. biceps brachii of six subjects in experiments for grading the rates of increase of isometric muscle tension until its maximum value. Correlation dependences were sought between the rate of increase of the tension, the force of maximum tension and the initial firing frequency of the activated MUs. A positive correlation was established between velocity and force in a narrow range of the average velocities. The initial firing frequency of the MUs was in positive correlation relation with the rate of increase of the tension, though only according to summated data. This connection may not be manifested for the single MUs. The pattern of the activity of the single MUs is considered to be only statistically connected with the activity parameters of the entire muscle.
D000328:Adult; D006801:Humans; D007537:Isometric Contraction; D007700:Kinetics; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction; D005082:Physical Exertion; D013997:Time Factors