Abstract

In course of biomechanical research one often searches for well-recognized physical phenomena, exhibited in body motion. This way sometimes inspires new concepts. Especially, the combination of several simultaneously appearing effects may provide entirely new possibilities. In this paper two physical phenomena are analyzed: resonance and detection. The first is commonly understood as a coincidence between the natural oscillation and harmonic excitation frequencies. When no damping exists in the system, the resonance results in unlimited increase of the amplitude. When damping exists, the external energy just covers the dissipative losses. Hence, from the energetic point of view, the resonance means maximum effect at a minimum effort. Detection in electronics means a detachment of a low-frequency component from a modulated signal. Detection requires some non-linear transformation of the Signal. The combination of the two phenomena involves the stimulation and supporting of oscillation and gaining additional advantage from the detection, which may appear as an increase of a propulsion force and/or a decrease of a resistance to motion. The non-linear effect necessary for detection may be provided by a difference of static and kinematic friction, parametric changes of body configuration, proper differentiation of a limb shape during propulsive and free phase of a motion or by many other means, consciously or unconsciously used by the subject. The resonance and detection phenomena have been demonstrated by use of a simple second-order mass-spring-damper model. The necessary simulation has been performed on a hybrid computer. The lecture has been illustrated by some examples concerning the applications in sport. Verf.-Referat