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Work-Related Ill Health
Published in Céline McKeown, Office Ergonomics and Human Factors, 2018
Limbs are considered to work most efficiently when moving within a natural/neutral, or comfortable, range. Over-extension of a joint, or the adoption of an irregular posture, so that the joint moves beyond its natural range, is more likely to result in the development of a ULD if performed repeatedly or is sustained for an extended period. Irregular wrist positions include ulnar and radial deviation and extension and flexion of the wrist. Ulnar deviation relates to the bending of the hand at the wrist in the direction of the little finger. Radial deviation relates to the bending of the hand at the wrist in the direction of the thumb. Extension relates to bending the hand upward at the wrist and flexion relates to bending the hand downward at the wrist. These positions are illustrated in Figure 11.1.
Work-Related III Health
Published in Céline McKeown, Office Ergonomics, 2007
Limbs are considered to work most efficiently when moving within a natural/neutral or comfortable range. Over-extension of a joint, or the adoption of an irregular posture, so that the joint moves beyond its natural range is more likely to result in the development of a ULD if performed repeatedly or is sustained for an extended period. Irregular wrist positions include ulnar and radial deviation and extension and flexion of the wrist. Ulnar deviation relates to the bending of the hand at the wrist in the direction of the little finger. Radial deviation relates to the bending of the hand at the wrist in the direction of the thumb. Extension relates to bending the hand upward at the wrist and flexion relates to bending the hand downward at the wrist. These positions are illustrated in Figure 11.1.
Ergonomics in the Office
Published in Stephen Pheasant, Christine M. Haslegrave, Bodyspace, 2018
Stephen Pheasant, Christine M. Haslegrave
On balance, a supported wrist when using the keyboard or mouse would seem to be desirable rather than otherwise, in that it will reduce the static loading on the muscles of the neck, shoulder and arm, as clearly shown by Aarås et al. (1997, 1998) for both keyboard and mouse work. There are two caveats to this general position. One is that supporting the wrist on the sharp edge of the desk (which you see quite commonly) can cause blunt trauma to the tissues of the front of the wrist (and in particular to the ulnar nerve). The second is that it may result in a ‘cocked’ (i.e., extended) wrist, which will in turn cause static loading of the muscles in the extensor compartment (i.e., back) of the forearm. The latter is particularly likely to be a problem if the keyboard is abnormally thick or if it is used in a steeply raked position. Both are highly undesirable. Both may be avoided by the use of a padded wrist support (while raising the seat height slightly to allow for this). In addition to reducing the mechanical loading on the lumbar spine, the laid-back sitting position (particularly when combined with the supported wrist) has the additional advantage of tending to increase the overall horizontal distance between the user’s shoulders and the keyboard. (The disadvantage that would accrue in terms of static load is eliminated by the supported wrist.) It follows, as a matter of geometry, that the degree of wrist deviation required to maintain the alignment of the fingers on the keys will be correspondingly diminished. As the trunk moves from a reclined position to an upright position, and then from an upright position to a forward sitting position, the elbows must also move out sideways to accommodate the width of the lower part of the rib cage. This results in a further and progressively more pronounced ulnar deviation of the wrist.
Tire Tread Removing Units in Central India: Risk Factors and Potential Interventions
Published in IISE Transactions on Occupational Ergonomics and Human Factors, 2020
Prabir Mukhopadhyay, Durwesh Jhodkar
Mean VAS and RPE scores were very high and this was expected as the workers were performing a task involving forceful exertion coupled with frequent forearm rotation in prone and supine directions. This was further accompanied by ulnar deviation of the wrist. Such elevated scores were expected because of deviated wrist and forearm postures, and are in accordance with similar studies (Kilbom, 1994; O’Sullivan & Gallwey, 2005). OVAKO scores for the back and legs were at a very high level, which was expected as the users worked in highly non-neutral postures, including forward stooping and twisting of the torso while working. The arms were also in abduction and adduction, which was indicated by an elevated OVAKO score of the arms. High SI scores indicated that the tasks were in the high-risk category. Similarly, elevated REBA and RULA scores further substantiate that the task being performed is in a high-risk category, thus requiring immediate ergonomic intervention. Several such interventions are provided below.