Differences in EMG/Force relationship between a single-joint exercise and a multi-joint exercise

Order Description
My dissertation will be looking at differences in EMG/force relationship between knee extension (single-joint) and leg press (multi-joint). Muscles under investigation are rectus femoris, vastus lateralis, and vastus medialis. I would like these 4 pages to be used for the introduction of my dissertation. Hypothesis of this study is that there will be a non-linear relationship between single-joint and multi-joint exercise