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Development and evaluation of an observational method for assessing repetition in hand tasks.

Latko-WA; Armstrong-TJ; Foulke-JA; Herrin-GD; Rabourn-RA; Ulin-SS
Am Ind Hyg Assoc J 1997 Apr; 58(4):278-285
An observational method developed for the assessment of repetition in hand tasks was examined in this study. The development of this method was founded on previous studies, preliminary job selection and categorization, and the application and improvement of the rating system used to grade hand activity repetition. Jobs were videotaped and documented prior to ergonomic analysis by an expert team. The development of the rating system was based on the analysis of 185 different jobs. The hand activity rating scheme incorporated the duration and frequency of rest pauses and the speed of hand movements. A set of 33 jobs was selected for the evaluation of the method. Hand exertion was calculated by averaging the number of forceful hand actions over several cycles. The team ratings of repetition and the number of exertions per second was significantly correlated, with a coefficient of 0.53. Recovery time was determined by computing the percentage of the work cycle spent with the hands idle. The team ratings of repetition and the percentage of resting were significantly correlated, with a coefficient of 0.58. Jobs rated as minimally, moderately, and highly repetitive had average recovery times of 64+/-16%, 26+/-22%, and 12+/-12%, respectively. Cycle time, defined as the interval during which the employee worked on one unit of production, was not significantly related to the team rating of repetition. Cycle times ranged from 1.2 to 214 seconds. When the same 33 jobs were reanalyzed by the same team at a later date, the two rating sets were highly correlated, with a coefficient of 0.88. The ratings from the second session were generally about 0.6 units higher than those of the first session. The authors conclude that although this observational rating system is sensitive, efficient, and consistent, further improvements are planned.
NIOSH-Publication; NIOSH-Grant; Workplace-studies; Repetitive-work; Work-analysis; Work-practices; Work-intervals; Musculoskeletal-system-disorders; Skeletal-movement; Musculoskeletal-system; Cumulative-trauma-disorders; Cumulative-trauma; Carpal-tunnel-syndrome; Hand-injuries; Vitamins; Age-factors; Ergonomics
Environmental & Indust Health the University of Michigan 1420 Washington Heights Ann Arbor, MI 48109-2029
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American Industrial Hygiene Association Journal
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University of Michigan at Ann Arbor, Ann Arbor, Michigan