NONLINEAR DYNAMICS OF THE BLOOD-FLOW STUDIED BY LYAPUNOV EXPONENTS

In order to gain an insight into the dynamics of the cardiovascular sy stem throughout which the blood circulates, the signals measured from peripheral blood flow in humans were analyzed by calculating the Lyapu nov exponents. Over a wide range of algorithm parameters, paired value s of both the global and the local Lyapunov exponents were obtained, a nd at least one exponent equaled zero within the calculation error. Th is may be an indication of the deterministic nature and finite number of degrees of freedom of the cardiovascular system governing the blood -flow dynamics on a time scale of minutes. A difference was observed i n the Lyapunov dimension of controls and athletes. (C) 1998 Society fo r Mathematical Biology.