A model of postural coordination dynamics.

Area of Science:

• Biomechanics
• Human Movement Science
• Dynamical Systems Theory

Background:

• Voluntary postural movement exhibits stable in-phase and antiphase hip-ankle coordination modes.
• Existing models fail to replicate observed fixed-points, phase transitions, and hysteresis in hip-ankle coordination.

Purpose of the Study:

• To develop a novel model capturing the complex dynamics of hip-ankle postural coordination.
• To incorporate principles of synergetics, nonlinear oscillators, symmetry breaking, and stochastic noise.

Main Methods:

• Utilized a synergetic approach with two nonlinear oscillators.
• Integrated terms for symmetry breaking and additive stochastic noise.
• Simulated coordination dynamics across varying movement frequencies.

Main Results:

• The model successfully replicates phase transitions between in-phase and antiphase coordination modes.
• Observed transitions occur predictably as movement frequency is scaled up or down.
• The model demonstrates hysteresis, with distinct transition frequencies during frequency increase and decrease.

Conclusions:

• The proposed nonlinear oscillator model effectively captures key dynamics of hip-ankle coordination.
• This model provides a more accurate representation of phase transitions and hysteresis in human postural control.
• Findings advance the understanding of coordination dynamics in voluntary movement.