Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

NIOSHTIC-2 Publications Search

Search Results

Bootstrap exploration of the duration of surface electromyography sampling in relation to the precision of exposure estimation.

Authors
Fethke-NB; Anton-D; Cavanaugh-JE; Gerr-F; Cook-TM
Source
Scand J Work, Environ & Health 2007 Oct; 33(5):358-367
NIOSHTIC No.
20033314
Abstract
OBJECTIVES: This study examined the effect of sampling duration, in units of work cycles, on the precision of estimates of exposure to forceful exertion obtained with surface electromyography (EMG). METHODS: Recordings of the activity of the flexor digitorum superficialis, extensor digitorum, and upper trapezius muscles over 30 consecutive work cycles were obtained for a random sample of 25 manufacturing workers, each of whom was performing a unique production task representing a portion of the whole job. The mean root-mean-square amplitude and the 10th, 50th, and 90th percentiles of the distribution function of the amplitude probability were calculated for each cycle. Bootstrap analyses were used to examine the precision of the summary measures as the sampling duration increased incrementally from 1 to 30 work cycles. Precision was estimated by calculating the coefficient of variation (CV) of the bootstrap distributions at each sampling duration increment. RESULTS: The average minimum sampling duration for a bootstrap distribution CV of 15% ranged from 2.0 (SD 1.5) cycles to 7.5 (SD 9.6) cycles, depending on muscle and summary measure. For a 5% CV, the average minimum sampling duration ranged from 11.9 (SD 9.0) to 20.9 (SD 10.5) cycles. CONCLUSIONS: The results suggest that sampling as few as three work cycles was sufficient to obtain a bootstrap distribution CV of 15% for some of the muscles and summary measures examined in this study. While limited to machine-paced, cyclic manufacturing work, these results will assist the development of exposure assessment strategies in future epidemiologic studies of physical risk factors and musculoskeletal disorders.
Keywords
Sampling; Sampling-methods; Worker-health; Musculoskeletal-system; Musculoskeletal-system-disorders; Mathematical-models; Statistical-analysis; Repetitive-work; Analytical-processes
Contact
Dr N Fethke, East Tennessee State University, Environmental Health, Campus Box 70682, Johnson City, TN 37614, USA
CODEN
SWEHDO
Publication Date
20071001
Document Type
Journal Article
Email Address
nathan-fethke@etsu.edu
Funding Type
Grant
Fiscal Year
2008
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-007945; Grant-Number-T42-OH-008491
Issue of Publication
5
ISSN
0355-3140
Source Name
Scandinavian Journal of Work, Environment and Health
State
TN; IA; WA
Performing Organization
University of Iowa - Iowa City
TOP