Evaluation of Grip Force Using Electromyograms in Isometric Isotonic Conditions

The purpose of this study was to develop a relationship to evaluate the grip force (force_rel) using the electromyogram (EMG_rel) of the flexor digitorum superficialis (FDS) and of the extensor digitorum (ED) according to the flexion-extension wrist angle (θ_f.e) and to the pronation-supination forearm angle (θ_p-s). Fifteen participants had to exert 3 levels of grip forces in 4 positions of the wrist combined with 3 positions of the forearm. The relationship is: force_rel = 0.0045· θ_f-e· EMG_rel(FDS) + 0.48· EMG_rel(FDS)-0.0014 · θ_f-e · EMG_rel(ED) -0.0016 · θ_p.s · EMG_rel(ED) + 0.4· EMG_rel(ED) This relationship can be used to estimate grip force for levels of strength lower than 50% of the maximal voluntary contraction.