Strength was the quality or state of being physically strong and physical strength was the measure of how muscularly strong an individual was. Physical strength was the amount of force exerted on a physical object. The demonstration of skill in strength was called physical prowess.
Boasting of their strength by a specimen was listed as one of the displays of the fear threat reaction by the Talosian Magistrate. When this reaction failed to elicit a positive response, the specimen would, as commented on by the Magistrate and as demonstrated by Captain Christopher Pike, be frustrated into a need to display physical prowess by throwing themselves against the transparency of their cell. Over a day later, when evaluating the factors in Yeoman J.M. Colt's favor as a potential mate for Pike, the Magistrate remarked upon her youth and strength. (TOS: "The Cage")