Effect of ship motion on spinal loading during manual lifting

This study investigated the effects of ship motion on peak spinal loading during lifting. All measurements were done on a ship at sea. In 1-min trials, which were repeated over a wide range of sailing conditions, subjects lifted an 18 kg box five times. Ship motion, whole body kinematics, ground reaction forces and electromyography were measured...

Pathophysiology of upper extremity muscle disorders

A review of the literature on the pathophysiology of upper extremity muscle disorders (UEMDs) was performed. An overview is given of clinical findings and hypotheses on the pathogenesis of UEMDs. The literature indicates that disorders of muscle cells and limitations of the local circulation underlie UEMDs. However, these disorders identified do...

Effect of precision demands and mental pressure on muscle activation and hand forces in computer mouse tasks

The objective of the present study was to gain insight into the effects of precision demands and mental pressure on the load of the upper extremity. Two computer mouse tasks were used: an aiming and a tracking task. Upper extremity loading was operationalized as the myo-electric activity of the wrist flexor and extensor and of the trapezius...

The effects of precision demands during a low intensity pinching task on muscle activation and load sharing of the fingers

High precision demands in manual tasks can be expected to cause more selective use of a part of the muscular synergy involved. To test this expectation, load sharing of the index finger and middle finger was investigated during a pinching task. Myoelectric activation of lower arm and neck-shoulder muscles was measured to see if overall level of...

Precision, comfort and mechanical performance of the Quadriso-tester, a quadriceps force measuring device

The mechanical performance, repeatability and comfort of the Quadrisotester, which assesses isometric knee extensor muscle strength, were examined. Twenty healthy subjects and 20 patients treated for unilateral anterior ligamenta cruciata insufficiency were tested. Intra-rater repeatability was determined by the testing and retesting of subjects...

Mechanisms of action of lumbar supports: A systematic review

Study Design. A systematic review and meta-analysis of studies on the putative mechanisms of action of lumbar supports in lifting activities. Objective. To summarize the evidence bearing on the putative mechanisms of action of lumbar supports. Summary of Background Data. A restriction of trunk motion and a reduction in required back muscle...

Force direction and physical load in dynamic pushing and pulling

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...

Physical risk factors for neck pain

To identify physical risk factors for neck pain, a systematic review of the literature was carried out. Based on methodological quality and study design, 4 levels of evidence were defined to establish the strength of evidence for the relationship between risk factors and neck pain. Altogether, 22 cross-sectional studies, 2 prospective cohort...

Abdominal muscles contribute in a minor way to peak spinal compression in lifting

In lifting, the abdominal muscles are thought to be activated to stabilize the spine. As a detrimental effect, they contribute to spinal compression. The existing literature is not conclusive about the biological relevance of this effect. From biological, mechanical and anatomical considerations it was hypothesised that the relative abdominal...

Physiological criteria for functioning of hands in the cold

Hands are important instruments in daily life. Without hands man is hardly able to function independently. Proper functioning of the hands is determined by several physiological parameters. These physiological parameters in turn are influenced by environmental factors. In this view of the literature, physiological processes in manual dexterity...