With the speed force seemly being about all forms of speed, not just running really fast, I'm thinking that the strength force would be more then just super-strength, like super stamina, leaping, nigh-invulnerability, since tensile strength is a form of strength, and perhaps willpower. Though she would be vulnerable when she's not tapping into the strength force, like Barry when he's moving like a normal person, because perhaps he is until he taps into the speed force to move really fast, like an on/off switch thing to energize them when needed.

She could perhaps also run/move faster in a lighter gravity kind of way, but not in a accelerated kind like a speedster.