In Marxian economics, the rate of exploitation is the divergence between labor productivity and the wage rate. In Marx's analysis of capitalist development, technological progress yields a higher ratio of constant capital (non-labor inputs) to variable capital (labor inputs), which lowers the demand for labor relative to capital inputs. This causes unemployment that services to exert a downward pressure on wages while productivity per worker rises, thus increasing the rate of surplus value extraction.
References
Rate of exploitation Wikipedia(Text) CC BY-SA