Well as I've gathered from sources on google, seiryoku zenyo seems to be the concept of exerting maximum force in a technique, but using very little effort. Seiryoku zenyo is also often translated to "maximum efficiency with very little effort." I can't think of direct examples, but I'm guessing seiryoku zenyo is the idea of throwing someone or using another technique effectively, but without exhausting a large amount of power to do so.

Though I might be wrong, correct me if I am.