Title
Trunk muscle activation and low back loading in lifting in the absence of load knowledge
Author
de Looze, M.P.
Steenhuizen, S.
Boeken-Kruger, M.C.
Baten, C.T.M.
Kingma, I.
van Dieën, J.H.
Publication year
2000
Abstract
People who know the actual mass of an object to be lifted normally prepare themselves before attempting a lift to control the movement and to minimize low back loading. In this study, the trunk muscular reactions and low back torque were investigated in the situation in which the individual did not know the actual mass but only had some idea of the range within which the mass lay. Nine males lifted boxes weighing 6.5 or 16.5 kg under the condition in which they knew the actual mass before attempting a lift (the 'known' condition) and the condition in which they only had the information that the mass would be within the range of 6.5 - 16.5 kg (the 'unknown' condition). The ground reaction forces and body movements were measured in the trials and, from these, the L5/S1 torques were calculated. The activation of back and abdominal muscles was also measured. For the 6.5 kg weight, a higher (16%) back muscle activation in grasping the box and a higher (10%) peak L5/S1 torque in actual lifting were observed in the 'unknown' compared with the 'known' weight condition. For the 16.5 kg weight, the back muscle activation was lower (10%) during grasping, and higher (10%) during lifting in the 'unknown' compared with the 'known' weight condition. Knowledge of the load had no effect on the activation of the abdominal muscles. It was concluded that in the so-called 'unknown' conditions, the risks of low back injury were increased in comparison with the conditions where the actual weight was known in advance.
Subject
Workplace
Lichaamshouding
Lichaamsbeweging
Tillen
Rugklachten
Hernia
Load knowledge
Movement control
Muscle activation
Spinal load
Abdominal wall musculature
Back muscle
Body movement
Controlled study
Human
Human experiment
Lifting effort
Low back pain
Lumbosacral spine
Movement (physiology)
Normal human
Weight lifting
Abdominal Muscles
Adult
Back
Electromyography
Humans
Lifting
Male
Multivariate Analysis
Muscle Contraction
Muscle, Skeletal
Psychomotor Performance
Torque
Weight-Bearing
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TNO identifier
276649
Source
Ergonomics, 43 (3), 333-344
Document type
article