It helps me to think of the row pull as a clean, that is finish driving with your legs before pulling with your arms. Doing the reverse in the recovery is important also.
So for the recovery from the finish position of a stroke - first straighten your arms, then swing upper body forward from the hips to reach a comfortable forward leaning position. THEN bend your knees and slide into the catch position, upper body shouldn't change position much at all.
At first row slowly until you can integrate it all into a smooth flowing stroke and recovery.
This explanation was stolen from CII, more discussion and a video can be found at www.concept2.com