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 (forcerel) using the electromyogram (EMGrel) of the flexor digitorum superficialis (FDS) and of the extensor digitorum (ED) according to the flexion-extension wrist angle (θf.e) and to the pronation-supination forearm angle (θp-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:forcerel = 0.0045· θf-e· EMGrel(FDS) + 0.48· EMGrel(FDS)–0.0014 · θf-e · EMGrel(ED) –0.0016 · θp.s · EMGrel(ED) + 0.4· EMGrel(ED)This relationship can be used to estimate grip force for levels of strength lower than 50% of the maximal voluntary contraction.