Related Experiment Video
Updated: May 31, 2026
08:12
Experimental Methods to Study Human Postural Control
Published on: September 11, 2019
Closed-loop and open-loop control of posture and movement during human trunk bending
1Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Science, 5A, Butlerov, Moscow, 117485, Russia. alexeialexandrov@inbox.ru
Biological Cybernetics
|June 29, 2011
Summary
Human trunk bending involves distinct motor control strategies. Closed-loop control adjusts hip synergy gain upwards and ankle synergy gain downwards during movement, unlike quiet standing.
Area of Science:
- Biomechanics
- Motor Control
- Human Movement Analysis
Background:
- Human forward upper trunk bending involves complex motor control.
- Understanding closed-loop (CL) and open-loop (OL) control is crucial for analyzing movement strategies.
- Natural synergies, or eigenmovements, provide a framework for dissecting multi-joint coordination.
Purpose of the Study:
- To investigate the distinct motor control mechanisms (CL and OL) during human forward upper trunk bending.
- To analyze the roles of hip (H-synergy) and ankle (A-synergy) natural synergies in trunk bending.
- To differentiate control strategies for the primary bending movement versus postural adjustments.
Main Methods:
- Utilized a two-joint (hip and ankle) biomechanical model of the human body.
- Analyzed movements along eigenvectors of the motion equation, termed natural synergies (H-synergy and A-synergy).
- Estimated CL control parameters via sudden support platform displacement during movement execution.
Main Results:
- CL gain increased in H-synergy and decreased in A-synergy during bending compared to quiet standing.
- OL control analysis indicated H-synergy follows Equilibrium Point (EP) theory.
- A-synergy control, focused on equilibrium maintenance, balances muscle and gravity forces, rendering EP theory inapplicable.
Conclusions:
- Human trunk bending employs distinct CL and OL control strategies for different movement components.
- The H-synergy, driving the bending motion, appears to be regulated by EP theory.
- The A-synergy, crucial for postural stability, operates on a different control principle, balancing forces rather than adhering to EP theory.
Related Concept Videos
01:17Open and closed-loop control systems
Control systems are foundational elements in automation and engineering. They are broadly categorized into open-loop and closed-loop systems. These classifications hinge on the presence or absence of feedback mechanisms, significantly influencing the system's performance, complexity, and application.
An open-loop control system operates without feedback from the output. It consists of two primary elements: the controller and the controlled process. The controller receives an input signal and...
An open-loop control system operates without feedback from the output. It consists of two primary elements: the controller and the controlled process. The controller receives an input signal and...
00:51Anatomical Movements
Anatomical movements refer to the various actions or motions that can be performed by the body's joints and muscles. These movements are described using specific terms to provide a standardized way of discussing and understanding the range of motion at different joints.
Here are some common anatomical movements:
Flexion and extension motions are in the sagittal (anterior–posterior) plane of motion. These movements take place at the shoulder, hip, elbow, knee, wrist, metacarpophalangeal,...
Here are some common anatomical movements:
Flexion and extension motions are in the sagittal (anterior–posterior) plane of motion. These movements take place at the shoulder, hip, elbow, knee, wrist, metacarpophalangeal,...
01:22Indirect Motor Pathways
The indirect motor or extrapyramidal pathways originate in the brainstem, the lower portion of the brain that connects it to the spinal cord. They consist of several distinct tracts, each with specialized functions. The four main tracts of the indirect motor pathways are the vestibulospinal tract, the reticulospinal tract, the tectospinal tract, and the rubrospinal tract.
The vestibulospinal tract originates in the vestibular nuclei of the brainstem. The vestibular system detects changes in...
The vestibulospinal tract originates in the vestibular nuclei of the brainstem. The vestibular system detects changes in...
01:10Bending
Pure bending is a fundamental concept in structural mechanics, essential for understanding how materials deform under symmetrical loads without direct forces. Pure bending occurs when prismatic members, such as beams, are subjected to equal and opposite moments that induce bending. The phenomenon is crucial as it allows for predicting stress distributions without the influence of axial or shear forces.
In pure bending, the bending stress in a beam is calculated based on the bending moment and...
In pure bending, the bending stress in a beam is calculated based on the bending moment and...
01:18Residual Stresses in Bending
In the study of elastoplastic members subjected to bending moments, understanding the loading and unloading phases is crucial for assessing material behavior and structural integrity. During the loading phase, as the bending moment increases, the material initially responds elastically, adhering to Hooke's Law, where stress is directly proportional to strain. When the load exceeds the yield strength, plastic deformation occurs, resulting in permanent strain and deformation that remains even...
01:18Unsymmetric Bending
Unsymmetrical bending occurs when the bending moment applied to a structural member does not align with its principal axis. This misalignment leads to complex stress distributions and deflection patterns that differ from those in symmetrical bending, and are essential for designing structures to withstand different loading conditions. In unsymmetrical bending, the neutral axis—where stress is zero—does not necessarily align with the geometric axes of the cross-section. The orientation of the...