What action is being applied to the character while hanging upside down?
Pull
Pulling may be described as the force transmitted axially by the means of a string, cable, chain, or similar one-dimensional continuous object, or by each end of a rod, truss member, or similar three-dimensional object.
In the image, the character is pulling the web line so that he can hang. The web itself is able to provide this support as it sticks to the surface.