Flexibilität spinaler Regelmechanismen; Vorteile und Gefahren

Summary

The maximum firing rate of the “final common pathway„ is limited to 50–60 imp/sec by mechanisms such as stretch reflex, tension limitation by Golgi tendon organs, presynaptic inhibition and Renshaw inhibition. Spinal mechanisms with stereotypic patterns would, for example, interrupt static contractions by excitation of Golgi tendon organs. By means of Hoffmann’ reflex investigations gonistic facilitation and antagonistic inhibition can be demonstrated. Immediately after increased H-potential by agonistic innervation a silent period can be observed, which is partially due to spinal limitations.

The flexibility of spinal controls in muscle spindle mechanism is performed either by γ-loop-innervation or direct activation of α-motoneurons. The other limiting mechanisms differ at their interneurons, which can be excited (stabilization) or inhibited (enhanced motor ability) by central pathways. In highly trained athletes the firing rate limits of the final common pathway can probably be reduced or cancelled out. This is probably one of the reasons, why sport injuries occur more frequently in highly trained athletes.