Anthropometry of Wheeled Mobility Project: Final Report

2.2.5 Grip Strength

Four types of grip strength measurements for the dominant hand were assessed. These included a power grip with the elbow in full extension (i.e. shoulders flexed 90-degrees and upper extremity fully extended), power grip with the elbow flexed 90-degrees, lateral pinch (i.e. with the pinch gauge between the thumb pulp and the radial aspect of the forefinger), and thumb-forefinger pinch (i.e. with the pinch gauge between the tips of the thumb and forefinger). These measurements are important to the design of and/or standards development for some types of hand tools, hardware and electrical controls (e.g. scissors, some types of door latches, knob controls). Grip strength was recorded with manual hand and pinch dynamometers (Jamar, Inc). WhMD users were required to perform three maximal efforts in each of the four types of grips with their dominant hand, with the mean value considered as the maximal force value for analysis. Force measurements were not obtained for those WhMD users that were unable to perform a grip or exert a grip force, or declined from grip measurements (e.g. due to pain or discomfort in the hand). If the person could not complete all three force repetitions, force data for that particular grip was not included in the analysis.

Prior analysis of a subset of this data (D’Souza et al., in review) showed maximal power grip forces to be greater on average by approximately 1% to 5% with the arm in full extension as compared to with the elbow flexed 90-degrees on average across gender and mobility device type. In light of this marginal difference, only the power grip data measured with the elbow flexed 90-degrees along with data on pinch grips are included in this report. Additional analyses of this data to study potential differences in grip strength capabilities by age and medical condition that may clinical relevance have also been reported (e.g. Joseph et al., 2010).