Solution Summary: Adjustable Height Work Bench
An adjustable height work bench is an engineering control that allows work materials to be placed at an optimal height. To alter the height of the work bench, a hand crank or motorized mechanism is used to raise and lower the telescoping legs.
Adjustable height work benches or platforms allows construction workers to stoop less because the materials and work surface are both kept at an optimal height. The optimal height for working on items is approximately 1 to 3 inches below the height of the elbow. Work at an optimal height has both physiological and productivity benefits.
Stooped postures can cause low back disorders, such as muscle strain or a disc herniation (“slipped disc”), which is bulging of disc material possibly pressing on the spinal cord or nerves that go into the leg. The adjustable height work bench can help reduce stooped postures by keeping the work between knee and shoulder height.
Overhead work can cause musculoskeletal disorders (MSDs) such as shoulder muscle strains; tendonitis, which is inflammation of the tendons; or rotator cuff tears, which is a rupture of a shoulder tendon. The adjustable height work bench can help reduce stooped overhead work by keeping the work between knee and shoulder height.
Stressful hand and wrist activity can cause musculoskeletal disorders (MSDs) such as muscle strains; tendonitis, which is inflammation of elbow and wrist tendons; or carpal tunnel syndrome, which is compression of a wrist nerve, resulting in finger numbness and loss of hand strength. The adjustable height work bench can help reduce stressful hand and wrist activity by keeping the work between knee and shoulder height.
Prolonged kneeling and squatting can cause musculoskeletal disorders (MSDs) such as osteoarthritis of the knee (degenerative joint disease), which is deterioration of the cartilage between knee joints causing bone on bone contact. The adjustable height work bench can help reduce prolonged kneeling and squatting by keeping the work between knee and shoulder height.
How Risks are Reduced:
There are several ways that adjustable height work benches reduce the risk of developing painful conditions in the muscles and joints. Workers are able to keep work at an optimal height, which is slightly below elbow level when standing. In general, work should be kept between knee and shoulder height, especially for manual material handling. Working at waist level reduces fatigue and risk of back problems associated with bending. Use of an adjustable height work bench may also encourage workers to perform assembly tasks at a safer height, possibly reducing the need for awkward overhead work postures.
Research has shown that workers who spend more time working in a stooped posture or other awkward back postures are at a higher risk for developing low back problems. Studies have reported a decrease in low back pain and stress among those working with materials kept at or near waist height. Manufacturers also report that the ability to set the work bench at any height allows workers to arrange materials between knee and shoulder height. Materials do not have to be moved as frequently, so there is less manual material handling of supplies and scaffolding parts. Research has shown that reduced manual materials handling decreases low back pain.
Working at waist height has also been shown to reduce repetitive motions of the hand and wrist. Repetitive motion is a risk factor for musculoskeletal disorders such as carpal tunnel syndrome and tendonitis.
There have not been independent published studies specifically evaluating the effect of adjustable height work benches on musculoskeletal disorder outcomes. Regardless, health and safety experts, such as ergonomists, encourage the use of adjustable workstations to accomodate for workers of different heights.
Effects on Productivity:
Productivity may indirectly be improved by using adjustable height work benches. Work at an optimal height reduces worker fatigue which could reduce the risk for developing musculoskeletal disorders.
An inexpensive method of raising work height is to work off of a stack of pallets. Along with adjustable height work benches, jigs, clamps, and vices should be used to maximize the benefit of working in an optimal posture.
Dan Anton, PT, PhD, ATC and Zack Sinner, SPT – Eastern Washington University
- Residential Construction
- Lay block or brick