Strength measures the character's raw physical potential in the short-term, and describes a character's capacity to change their physical environment. It defines how much the character can lift or push, how fast they can run, what they are capable of deforming, and how much damage they can do.
Strength also governs actions related to martial hand-to-hand training. Wrestling, boxing, and martial arts capability are the pervue of the Strength trait in the short-term.
In abstract, Strength combines a number of functions, as a number of different mechanisms contribute to making someone 'strong'. It represents not only the raw power of a single muscle, but the ability to stretch the limits of the body, the sum of muscles, bones, and leverage that can be marshalled to produce force, coordination between disparate strength-related activities, and the speed at which power can be brought to bear or muscles made to move.
A high strength trait would be appropriate for a sprinter, any kind of power athlete, a farmhand, a martial arts expert, a wrestler, and most people who work with their hands.