PubMed Health⌕ Search

PubMed · 11868848

Do specially designed visual display unit lenses create increased postural load compared with single-vision lenses during visual display unit work?

Abstract

Three different types of spectacle lenses, specially designed for visual display unit (VDU) work, were compared with single-vision lenses regarding postural load. The different corrections effect on postural load was measured by using electromyography. Muscle loads were recorded from the trapezius muscle and the infraspinatus muscle. Continuous measurements of body posture were measured by using three dual axis inclinometers attached to the head, back, and upper arm. No significant differences were found between the single-vision lenses and the specially designed VDU lenses regarding muscle load. Small differences were found regarding the head angle. The study concludes that these new lens designs create interesting opportunities for the optometrist to optimize the visual conditions for VDU workers.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Gunnar Horgen, Arne Aarås, Helene Kaiser, Magne Thoresen. 2002. Do specially designed visual display unit lenses create increased postural load compared with single-vision lenses during visual display unit work?. https://doi.org/10.1097/00006324-200202000-00013

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

FMRI evidence for a 'parietal reach region' in the human brain.

Event-related functional magnetic resonance imaging was used to examine activation in the posterior parietal cortex when subjects made pointing movements or saccades to the same spatial location. One region, well positioned to be homologous to the monkey parietal reach region (PRR), responded preferentially during memory-delay trials in which the subject planned to point to a specific location as compared to trials in which the subject planned to make a saccade to that same location. We therefore conclude that activation in this region is related to specific motor intent; i.e. it encodes information related to the subject's intention to make a specific movement to a particular spatial location.

Arm↗

Depression of activity in the corticospinal pathway during human motor behavior after strong voluntary contractions.

The corticospinal system plays an important role in control of voluntary movements in primates. Recently, we demonstrated that the effectiveness of this system is depressed after maximal exercise. Because the depression was absent after antidromic activation of the motoneurons, we argued that transmission across corticospinal synapses was involved. Here, we explore the possible functional consequences of such a depression. In humans, direct electrical stimulation of axons of corticospinal neurons at the cervicomedullary level evokes motor potentials in elbow flexor muscles. When tested during relaxation after a maximal voluntary contraction (MVC) of the elbow flexors, potentials in biceps brachii and brachioradialis were depressed for approximately 90 sec. The potentials were also depressed, although less markedly, when tested during a weak elbow flexion. Brief intermittent MVCs abolished the depression transiently, but during the intervening periods of relaxation, the depression appeared similar to that during continuous relaxation. The depression was greatest during relaxation after a 10 sec MVC and smaller after submaximal contractions. To look for effects of the depression on voluntary activity, we compared bilateral matching weak elbow flexions. After a conditioning 10 sec maximal elbow flexion of one arm, the electromyographic activity produced on that side was reduced relative to the activity on the contralateral side. Our findings support the view that synapses in the corticospinal system are depressed after strong voluntary contractions during both relaxation and activity. Furthermore, this depression can affect the production of voluntary movement.

Arm↗