A. The inverted T-shaped apparatus. Here the mass distribution is hidden by the balsawood covers. B. Schematic drawing of the device, with w representing the distance between the fingers (w = 8 cm). Load forces (LF, parallel to the grip surface) and grip forces (GF, perpendicular to the grip surface) were measured. T = thumb, I = index. C. Configurations of the bars on the grip device used in the experiments 1 and 2. The arrows represent the location of the center of mass (CM). B = brass bar, P = plastic bar.