PMC

Grip force magnitude decreased with increase in handle diameter (p<0.05) except when comparing force magnitudes for handle 1 and handle 2, and handle 1 and handle 3. Grip force vector direction decreased with increase in handle diameter (p<0.05) except when comparing force directions for handle 2 and handle 3. A decrease in force vector direction corresponds to clockwise rotation in force vector toward the thumb-tip ().

Grip Apertures during transport to grasp the object. (a) Shows the grip apertures averaged over participants for each of the 5 conditions from start until just after MGA (100%, line) is reached. Participants started with their hand pinched. Their grip apertures were wider in the ‘move’ compared to the ‘drink’ conditions. In the former conditions, we observed significant modulation in grip aperture relating to the presence of a handle, even though the dimensions of the cup that was moved were identical. The MGA was largest in the move conditions when the cup had no handle. It was significantly reduced when the cup had a handle oriented away and when this was oriented toward the grasping hand. The grip apertures for the two ‘drink’ conditions, namely with a ‘handle on cup’ or a ‘handle only’ showed no significant modulation. (b) Represents the grip aperture histograms for each of the 3 move conditions. The data has been grouped in 10% of MGA time points, demonstrating significant differences in grip aperture between conditions over time (handle toward vs no handle occurring at 60% until 100% of MGA, handle away vs no handle occurring at MGA, see results section). *p =  < 0.05, **p < 0.001.

(a) The No-grip handle showing finger guard for finger positioning, (b) Pinch grip handle with a pinch pulp grip, and (c) The Power grip handle.

Maximal grip force vector magnitudes. Grip force magnitude decreases with handle diameter for both males and females.