title: Handle Shape Affects the Grip Force Distribution and the Muscle Loadings During Power Grip Tasks.
abstract: The objectives of this study were to investigate the effect of handle shape on the grip force distribution in the hand and on the muscle forces during maximal power grip tasks. Eleven subjects maximally grasped 3 handles with different external shapes (circular, elliptic, and double-frustum). A handle dynamometer, equipped with both a force sensor and a pressure map, was used to record the forces exerted at the hand/handle interface. The finger and wrist joint postures were also computed from synchronized kinematic measurement. These processed data were then used as input of a biomechanical hand model to estimate muscle forces. The results showed that handle shape influences the maximal grip force, the grip force distribution, and the finger joint postures. Particularly, we observed that the elliptical shape resulted in a 6.6% lower maximal grip force compared with the circular and double-frustum handle. Concomitantly, the estimated muscle forces also varied significantly according to the handle shape, with up to 48% differences for the flexor digitorum superficialis muscle for example. Interestingly, different muscle coordination strategies were observed depending on the handle shape, therefore suggesting a potential influence of these geometrical characteristics on pathological risks such as tendonitis.
authors.affiliation: Aix-Marseille University, Institute of Movement Sciences, UMR CNRS 7287, 13288 Marseille, France.
authors.forename: Jérémy
authors.initials: J
authors.lastname: Rossi
authors.forename: Benjamin
authors.initials: B
authors.lastname: Goislard De Monsabert
authors.forename: Eric
authors.initials: E
authors.lastname: Berton
authors.forename: Laurent
authors.initials: L
authors.lastname: Vigouroux
mesh_terms: D000328:Adult; D006804:Ergonomics / Q000295:instrumentation / Q000379:methods; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D008328:Man-Machine Systems; D009119:Muscle Contraction / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D011312:Pressure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013647:Task Performance and Analysis