Related Experiment Video
Updated: Aug 12, 2026
09:46
Training Persons with Spinal Cord Injury to Ambulate Using a Powered Exoskeleton
Published on: June 16, 2016
Spine loading as a function of lift frequency, exposure duration, and work experience
W S Marras1, J Parakkat, A M Chany
1Biodynamics Laboratory, The Ohio State University, Columbus, 43210, USA. marras.1@osu.edu
Clinical Biomechanics (Bristol, Avon)
|November 29, 2005
Summary
Repetitive lifting increases spine loading, especially for novices and with unaccustomed frequencies. Motor programming, not just frequency or duration, significantly impacts biomechanical spine loads over an 8-hour workday.
Area of Science:
- Occupational biomechanics
- Ergonomics
- Manual materials handling
Background:
- Previous studies on lifting frequency focused on whole-body fatigue, not spine loads.
- Understanding of biomechanical spine loading may be inaccurate due to extrapolation from short lifting bouts.
Purpose of the Study:
- To document changes in spine loading based on experience, lift frequency, and duration during an 8-hour workday.
- To investigate the biomechanical implications of repetitive lifting over extended periods.
Main Methods:
- 12 novice and 12 experienced manual materials handlers performed repetitive lifts.
- Lifts varied in load and frequency over an 8-hour period.
- Spine loads (compression, shear) were assessed using an EMG-assisted biomechanical model.
Main Results:
- Spinal loads increased after 2 hours of lifting, irrespective of frequency.
- Inexperienced lifters experienced greater spinal loading than experienced lifters.
- Highest loads occurred at unaccustomed lift frequencies and weights.
Conclusions:
- Increased spine loading is linked to altered muscle recruitment patterns, specifically increased coactivation.
- Prior motor programming is crucial in determining spine loads during repetitive lifting.
- Extrapolating findings from short lifting periods to extended workdays is insufficient for biomechanical analysis.
Related Concept Videos
01:15Stress: General Loading Conditions
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.
01:21Fatigue
Fatigue occurs when materials rupture under repeated or fluctuating loads, even at stress levels far below their static breaking strength. It typically results in brittle failure, even for ductile materials. It is a critical consideration in designing machines and structural components subjected to repetitive or varying loads. The nature of these loadings can range from fluctuating loads like unbalanced pump impellers causing vibrations to repeatedly bending a thin steel rod wire back and forth...
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...
01:16Elastic Curve from the Load Distribution
The structural behavior of beams under distributed loads is critical for engineering analysis, which focuses on predicting how beams bend and react under such conditions. Different types of beams (e.g., cantilever, supported, or overhanging) behave differently under distributed load conditions.
For all beams, the analysis of the beam's reaction to distributed loads begins by understanding the relationship between a beam's load and the resulting shear forces and bending moments. Initially, this...
For all beams, the analysis of the beam's reaction to distributed loads begins by understanding the relationship between a beam's load and the resulting shear forces and bending moments. Initially, this...
01:16Eccentric Loading
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 load.
01:19Impact Loading
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,...