The spatial dependency of shoulder muscular demands during upward and downward exertions

Alicia L. Nadon, Meghan E. Vidt, Amy Y. Chow, Clark R. Dickerson

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Lifting and lowering are common occupational tasks contributing to shoulder injury risk. Quantifying task interaction with physical demand can precipitate better workstation designs. Nineteen university-aged males performed one-handed, submaximal upward/downward manual force exertions at 70 hand locations; unilateral electromyography (EMG) of 14 muscles was recorded. EMG across planes was evaluated with ANOVA. Predictive equations for muscle activity throughout the reach envelope were developed with stepwise regression. Total muscle activity (sum of individual muscle activity) was most sensitive to vertical hand location for upward exertions, where activation at superior locations was 192% of values for inferior locations. For upward exertions, activation differences for hand location occurred along all anatomical axes, and along anterior/posterior and superior/inferior axes for downward exertions. Predictive equations were non-linear, reflecting complex muscular demand with three-dimensional hand location. This work details foundational exposure data for lifting/lowering exertions. Results are applicable to workstation design to minimise occupational shoulder muscular demands. Practitioner Summary: Lifting and lowering in the workplace contribute to shoulder injury risk. Shoulder muscle activity magnitudes revealed a dependence on three-dimensional hand location in the reach envelope for a defined hand force. This information can inform evidence-based workstation designs that reduce shoulder muscular demands for numerous materials handling scenarios.

Original languageEnglish (US)
Pages (from-to)1-13
Number of pages13
JournalErgonomics
DOIs
StateAccepted/In press - Feb 24 2016
Externally publishedYes

Fingerprint

Spatial Analysis
Hand
Muscle
Muscles
workstation
Electromyography
activation
Chemical activation
demand
Workplace
Materials handling
Analysis of variance (ANOVA)
Analysis of Variance
Precipitates
workplace
scenario
regression
university
interaction
evidence

Keywords

  • electromyography
  • hand force
  • occupational
  • reach envelope
  • Upper extremity

ASJC Scopus subject areas

  • Human Factors and Ergonomics
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

The spatial dependency of shoulder muscular demands during upward and downward exertions. / Nadon, Alicia L.; Vidt, Meghan E.; Chow, Amy Y.; Dickerson, Clark R.

In: Ergonomics, 24.02.2016, p. 1-13.

Research output: Contribution to journalArticle

Nadon, Alicia L. ; Vidt, Meghan E. ; Chow, Amy Y. ; Dickerson, Clark R. / The spatial dependency of shoulder muscular demands during upward and downward exertions. In: Ergonomics. 2016 ; pp. 1-13.
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