Rambling and trembling in response to body loading

Area of Science:

• Biomechanics
• Human postural control
• Sensorimotor systems

Background:

• Postural sway is theorized to be regulated by at least two distinct subsystems.
• Rambling-trembling analysis, based on the equilibrium point hypothesis, is a key method for differentiating these subsystems.
• This analysis separates center of pressure (COP) signals into 'rambling' (shifts between equilibrium points) and 'trembling' (deviations from the COP signal).

Purpose of the Study:

• To investigate how external loads differentially affect the rambling and trembling components of postural sway.
• To compare the dynamics of these COP signal components under various body loading configurations.

Main Methods:

• Utilized Rambling-Trembling analysis to dissect center of pressure (COP) signals.
• Employed Detrended Fluctuation analysis to compare signal patterns.
• Examined postural sway under different external load conditions.

Main Results:

• External loading altered the dynamics of the trembling component independently of postural sway area and the rambling component.
• The dynamics of the rambling component were affected only during backloading, which also significantly increased the postural sway area.
• Trembling dynamics were modified irrespective of changes in the overall postural sway area.

Conclusions:

• External loads can modulate the trembling subsystem of postural control without necessarily affecting the central control of equilibrium point shifts (rambling).
• The findings suggest that peripheral mechanisms and reflexes, potentially driving the trembling component, are more sensitive to external loading than central mechanisms.
• Loaded standing alters postural control strategies, with distinct impacts on central and peripheral contributions to maintaining balance.