Limited applicability of stochastics and comparing it with the new methods of multidimensional phase space were showed. Quantitative measures of the parameters are quasi-attractors for evaluation of chaotic dynamics on the example of the little finger abductor muscle. Method of multidimensional phase space carried out the study and modeling of complex biological objects (complexity). The state of the neuromuscular system is studied in two modes: a weak muscle tension and strong, almost the maximum force. Used quasi-attractors volumes of multidimensional phase spaces, which provide the identification of real changes in the parameters of the functional state with weak muscles (F1=5 daN) and strong (F2=10 daN) static stress. Analysis of the timebase signal x1(t) obtained with myograph, and autocorrelation functions A(t) signal showed their unrepeatability. Comparative analysis of the biomechanical system is made on the basis of registration of quasi-attractor’s volume, as well as on the basis of analysis of the Shannon’s entropy E. Volume of quasi-attractor’s movements x1(t) и x2(t)=dx1/dt at low load is slightly less than similar amounts of displacement of vector (х1, х2)Т  under a heavy load of musculus abductor digiti mini. The values ??of the Shannon entropy under a heavy load are statistically unchanged. Values of the Shannon entropy under heavy load, not statistically vary on the advisability of entropy approach in the assessment of muscular efforts and the impossibility of application of the theorem of Glansdorff—Prigogine (thermodynamics of nonequilibrium systems) in psychophysiological research. Overall, restricting the use of methods of stochastics and the possibility of using the method of multidimensional phase spaces, have been demonstrated in the Eskov—Zinchenko effect.