Signs Of Efficiency
Because sign languages have different major articulators (arms and hands instead of lips and tongue), they provide an opportunity to discover aspects of effort that are not as apparent in spoken languages. [...]they can be considered representative of how we might expect any arbitrarily selected sign language to behave, and indeed, of the more than twenty sign languages we have examined since this initial study, the results have been consistent.\n All destabilizing movements require expending reactive effort, but because the torso's moment of inertia is larger for rocking, the inherent resistance to rocking is larger, so we do not have to expend quite as much reactive effort.
Nathan Sanders and Donna Jo Napoli.
"Signs Of Efficiency".