title: The effects of hand force variation on shoulder muscle activation during submaximal exertions.
abstract: Upper limb injuries are highly prevalent in the workplace and new tools are needed to proactively design workstations to reduce injury risk. The objective was to characterize spatial, load and direction dependency of muscle activity for hand exertions in the upper limb workspace. Electromyographic signals were collected from 14 upper limb muscles during exertions for all combinations of 4 submaximal hand forces (20/30/50/60 N) in 6 cardinal (up/down/left/right/forward/backward) directions at 5 hand locations. Linear muscle activity increases accompanied increased hand forces. Total muscle activity increases between 20 and 60 N hand forces ranged by direction from 92% (downward) to 189% (right). Prediction equations for all muscles depended on hand force, and linear, quadratic and interaction permutations of hand location. Muscle activity associated with manual tasks is load, direction and spatially dependent. Equations developed to describe these complex relationships can be used to better design future and evaluate current occupational activities.
authors.affiliation: a Department of Kinesiology , University of Waterloo , Canada.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Meszaros
authors.affiliation: b Exercise Science and Health Promotion , Arizona State University , USA.
authors.forename: Meghan E
authors.identifier: http://orcid.org/0000-0002-8811-8569
authors.initials: ME
authors.lastname: Vidt
authors.affiliation: a Department of Kinesiology , University of Waterloo , Canada.
authors.forename: Clark R
authors.initials: CR
authors.lastname: Dickerson
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D004576:Electromyography; D006804:Ergonomics; D006225:Hand / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion; D011187:Posture; D012782:Shoulder / Q000502:physiology*; D055815:Young Adult
keywords: electromyography; hand force; muscle; upper limb; work envelope