Whole-body pointing as superposition of two multi-joint components.

Area of Science:

• Motor control
• Biomechanics
• Neuroscience

Background:

• Understanding movement control involves analyzing synergies between different body segments.
• The interplay between reaching movements and postural stability is crucial for dynamic balance.
• Previous research has not fully explored trade-offs in control synergies within joint configuration spaces.

Purpose of the Study:

• To investigate the interaction between reaching movements (legs and trunk) and postural balance.
• To quantify performance-stabilizing synergies at different control hierarchy levels.
• To explore trade-offs between these synergies in joint configuration spaces.

Main Methods:

• Participants performed reaching tasks involving shoulder and endpoint movements.
• Motion kinematics were analyzed in a two-dimensional action space.
• The uncontrolled manifold hypothesis quantified variance components and synergy indices.

Main Results:

• Synergy indices confirmed stabilization of the task-specific effector coordinate.
• Minor trade-offs were observed between control hierarchy levels.
• Shoulder trajectory movements showed smaller variance components without affecting the synergy index.
• Postural constraints reduced inter-trial variance in joint configuration space.

Conclusions:

• Movement control strategies effectively stabilize reaching tasks.
• Postural constraints play a role in refining movement control without compromising task-specific synergies.
• Findings contribute to understanding neural control with spatial referent coordinates in natural tasks.