Correlation and relaxation features in physiological signals of the human neuromuscular activity

Using the memory function formalism and the technique of the projection operators for time correlation functions, the analysis of age-related alterations in relaxation processes and the complex interdependence between the short- and long-range correlations in the human force output variability is carried out. The essential differences in character of the short- and long-range correlations and the relaxation times for different age groups (20-24, 64-69, 75-90 years old) are revealed. Particularly, the crucial role of the short-range correlation component in neuromuscular dynamics during the process of aging is shown. Moreover, the local properties of the relaxation processes in neuromuscular activity derived by means of the specific localization procedure for the kinetic and relaxation parameters are discovered. The revealed correlation and relaxation features of the human neuromuscular activity allow to be gain a better understanding the physical mechanisms underlie the biological aging phenomenon.