Weight knowledge and weight magnitude: impact on lumbosacral loading
Ahmed T Farrag1, Walaa H Elsayed, Mohsen M El-Sayyad
1a Basic Science Department , Faculty of Physical Therapy, Cairo University , Cairo , Egypt.
Ergonomics
|October 21, 2014
Summary
Weight knowledge significantly impacts spinal loads during lifting, especially for lighter weights. Unexpected lighter loads can increase tissue loading to levels similar to heavier weights due to muscle co-contraction.
Area of Science:
- Biomechanics
- Occupational Health
- Ergonomics
Background:
- Lifting mechanics are influenced by factors like weight magnitude and knowledge.
- The interaction between weight knowledge and magnitude on spinal loads remains under-explored.
Purpose of the Study:
- To investigate the interaction effect of weight knowledge and weight magnitude on lumbosacral forces and moments during symmetrical lifting.
Main Methods:
- Participants performed symmetrical lifts with three distinct weights under known and unknown conditions.
- A biologically assisted dynamic model was employed to compute spinal loading parameters.
Main Results:
- Weight magnitude affected all measured spinal loading parameters.
- Weight knowledge moderately impacted compression (5%) and spinal moments.
- For light weights, unknown conditions increased compression by 16% and anterior-posterior shear by 7.2% compared to known conditions; this difference was negligible (<1%) for heavy weights.
Conclusions:
- Weight knowledge is a critical factor influencing spinal loading, particularly at lower weight levels.
- Increased muscular co-contraction likely explains higher spinal loads when lifting unexpectedly light weights.
- Consideration of weight knowledge is essential for accurate risk assessment in lifting tasks, especially with lighter loads.
More Related Videos
Related Concept Videos
01:19Impact Loading
951
Impact loading occurs when a moving object collides with a stationary structure, such as a rod with a uniform cross-sectional area fixed at one end. Under these conditions, the rod absorbs the kinetic energy from the striking object, leading to deformation and subsequent stress development. As the rod returns to its original position and reaches maximum stress, the absorbed energy, initially manifested as kinetic energy, transforms entirely into strain energy.
In cases of elastic deformation,...
In cases of elastic deformation,...
951
01:13Resultant of a General Distributed Loading
1.2K
While designing structures exposed to non-uniform loads, it is crucial to consider the resultant force and its location. This resultant force is a single vector representing the net force applied due to the distributed load.
Examples such as load distribution due to wind and load distribution on a bridge illustrate how this concept is used to analyze and design safe, reliable structures under variable loading conditions. Most structures, such as residential buildings, bridges, and towers, are...
Examples such as load distribution due to wind and load distribution on a bridge illustrate how this concept is used to analyze and design safe, reliable structures under variable loading conditions. Most structures, such as residential buildings, bridges, and towers, are...
1.2K
01:29Load along a Single Axis
738
In structural engineering, the analysis of beams subjected to varying loads is a critical aspect of understanding the behavior and performance of these structural elements. A common scenario involves a beam subjected to a combination of different load distributions.
Consider a beam of length L subjected to a varying load, which is a combination of parabolic and trapezoidal load distribution along the x-axis. In this case, it is essential to determine the resultant loads, their locations, and...
Consider a beam of length L subjected to a varying load, which is a combination of parabolic and trapezoidal load distribution along the x-axis. In this case, it is essential to determine the resultant loads, their locations, and...
738
01:15Stress: General Loading Conditions
732
To grasp the intricacy of real-world conditions where multiple loads are applied simultaneously to a structure, one might visualize a section passing through a specific point within a body, aligned parallel to the xy plane. This section is subjected to various forces, including original loads, normal forces, and shearing forces.
The shearing force, possessing potential directionality within the plane of the section, is simplified into two component forces running parallel to the x and y axes....
The shearing force, possessing potential directionality within the plane of the section, is simplified into two component forces running parallel to the x and y axes....
732
01:16Eccentric Axial Loading in a Plane of Symmetry
755
Eccentric axial loading occurs when an axial load is applied away from the centroidal axis of a structural member. This scenario is common in engineering, where structural elements may not be directly aligned due to various design or functional requirements.
755
01:16Eccentric Loading
1.3K
Eccentric loading is a crucial concept in the study of structural engineering and mechanics, particularly when analyzing the stability and stress distribution in columns. Unlike centric loading, where the force is applied along the centroidal axis, causing uniform compression, eccentric loading occurs when a force is applied off-center. This off-center application introduces not only direct compressive stress but also bending stress, significantly influencing the column's behavior under...
1.3K