Theoretical Analysis of the Force and Position Synergies in Two-Joint Movements

• Veröffentlicht in: Нейрофизиология
• Datum: 2016
• 1. Verfasser: Kostyukov, A.I.
• Format: Artikel
• Sprache: Englisch
• Veröffentlicht: Інститут фізіології ім. О.О. Богомольця НАН України 2016
• Online Zugang: https://nasplib.isofts.kiev.ua/handle/123456789/148336
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Zitieren: Theoretical Analysis of the Force and Position Synergies in Two-Joint Movements / A.I. Kostyukov // Нейрофизиология. - 2016. - Т. 48, № 4. - С. 315-325. — Бібліогр.: 20 назв. — англ.

A theoretical approach is proposed to define the force and position singular points (FSPs
 and PSPs) in the circular, ellipsoidal, and linear planar two-joint movements produced under
 steady loadings directed along the movement traces. The FSPs coincide with changes in
 the direction of the force moments acting around the joints; the PSPs show the locations
 of the extrema at the joint angle trajectories. The force synergy (defined by the location of
 FSPs) provides a strong influence on the activation synergy; the latter is largely described by
 correlations between the activities recorded from the muscles participating in the movement.
 The position synergy (defined by the location of PSPs) is responsible for a hysteresis-related
 modulation of the activation synergy. Geometrical procedures are proposed to define positions
 of the FSPs and PSPs along various movement traces; this can provide a general description
 of the force and position synergies for the movements. The force synergies in the circular
 movements cover four sectors with diverse loading combinations of the flexor and extensor
 muscles belonging to different joints. The variability of the synergy effects for changes in
 the size and position of the circular trajectories is analyzed; the synergy patterns are also
 considered for ellipsoidal and linear movement traces. A Force Feedback Control Hypothesis
 is proposed; it allows one to explain the decrease in the number of controlled variables during
 real multi-joint movements.