Title
Force direction and physical load in dynamic pushing and pulling
Author
de Looze, M.P.
van Greuningen, K.
Rebel, J.
Kingma, I.
Kuijer, P.P.F.M.
Publication year
2000
Abstract
In pushing and pulling wheeled carts, the direction of force exertion may, beside the force magnitude, considerably affect musculoskeletal loading. This paper describes how force direction changes as handle height and force level change, and the effects this has on the loads on the shoulder and low back. Eight subjects pushed against or pulled on a stationary bar or movable cart at various handle heights and horizontal force levels while walking on a treadmill. The forces at the hands in the vertical and horizontal direction were measured by a force-transducer. The forces, body movements and anthropometric data were used to calculate the net joint torques in the sagittal plane in the shoulder and the lumbo-sacral joint. The magnitudes and directions of forces did not differ between the cart and the bar pushing and pulling. Force direction was affected by the horizontal force level and handle height. As handle height and horizontal force level increased, the pushing force direction changed from 45°(SD 3.3°) downward to near horizontal, while the pulling force direction changed from pulling upward by 14°(SD 15.3°) to near horizontal. As a result, it was found that across conditions the changes in force exertion were frequently reflected in changes in shoulder torque and low back torque although of a much smaller magnitude. Therefore, an accurate evaluation of musculoskeletal loads in pushing and pulling requires, besides a knowledge of the force magnitude, knowledge of the direction of force exertion with respect to the body.
Subject
Workplace
Force direction
Musculoskeletal load
Pulling
Pushing
Back
Force transducer
Human experiment
Lifting effort
Movement (physiology)
Muscle force
Normal human
Physical parameters
Shoulder
Treadmill ergometry
Adult
Exercise Test
Humans
Joints
Lifting
Lumbar Vertebrae
Lumbosacral Region
Male
Sacrum
Shoulder Joint
Torque
Videotape Recording
Walking
Weight-Bearing
To reference this document use:
http://resolver.tudelft.nl/uuid:442c0356-28a0-4e20-b1a6-e53fe50fbabf
TNO identifier
235456
ISSN
0014-0139
Source
Ergonomics, 43 (3), 377-390
Document type
article