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Mining Publication: Trunk Extension Strength and Muscle Activity in Standing and Kneeling Postures
Keywords: Back Electromyography Kneeling Physiology Standing 
 Torque reaction
Original creation date: August 1997
Authors: S Gallagher
Peer Reviewed Journal Article - August 1997
Download PDF Document (0.67 MB)
NIOSHTIC2 Number: 00240151
Spine 1997 Aug 22(16):1864-1872
The effects of posture on trunk muscle strength under isometric and isokinetic conditions in 21 healthy male volunteers and the associated electromyographic activity for eight trunk muscles were investigated. The men performed 12 trunk extension exertions in standing and kneeling postures. Isometric tests were performed at 22.5, 45, and 67.5 degrees of trunk flexion. Isokinetic tests were performed at three velocities: 30, 60, and 90 degrees per second. Electromyographic data were collected from eight trunk muscles to assess muscle recruitment under each condition. A priori orthogonal contrasts were specified for analysis of both torque and electromyographic data. The findings suggest that the kneeling posture was associated with a 15% decrease in peak torque output when contrasted with standing. However, no concomitant change was noted in trunk muscle activity. Trunk hyperflexion and increasing rotational velocity were associated with reduced torque in both postures. Trunk muscle activity was primarily affected by changes in trunk angle and velocity of contraction. The authors conclude that a reduced extensor capability existed in the kneeling posture in spite of equivalent trunk muscle activity. The similar activation patterns in both postures suggests that the strength deficit did not result from alterations in trunk muscle function. They suggest that it may be due to reduced capability to rotate the pelvis in the kneeling position, due to a disruption of the biomechanical linkage of the leg structures.
Image of publication Trunk Extension Strength and Muscle Activity in Standing and Kneeling PosturesPeer Reviewed Journal Article - August 1997
Download PDF Document (0.67 MB)
NIOSHTIC2 Number: 00240151
Spine 1997 Aug 22(16):1864-1872
See Also
Analysis of Applied Forces and Electromyography of Back and Shoulders Muscles When Performing A Simulated Hand Scaling Task
A Comparison of Fatigue Failure Responses of Old Versus Middle-Aged Lumbar Motion Segments in Simulated Flexed Lifting
Effects of Lifting in Four Restricted Postures
Effects of Posture on Back Strength and Lifting Capacity
The Effects of Restricted Workspace on Lumbar Spine Loading
Electromyography of the Thigh Muscles during Lifting Tasks in Kneeling and Squatting Postures
Lifting in Stooped and Kneeling Postures: Effects on Lifting Capacity, Metabolic Cost, and Electromyography of Eight Trunk Muscles
Locomotion in Restricted space: Kinematic and Electromyographic Analysis of Stoopwalking and Crawling
Nature and Cost of Low Back Pain
Physiological Responses and Subjective Discomfort of Simulated Whole-Body Vibration From a Mobile Underground Mining Machine
Page last reviewed: September 21, 2012
Page last updated: September 21, 2012
Content source: National Institute for Occupational Safety and Health, Mining Program
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