"In his postdoctoral work (Habilitationsschrift) Frank investigated the isometric and isotonic contractile behaviour of the heart and it is this work that he is best known for. Frank's work on this topic preceded that of Ernest Starling, but both are usually credited with providing the foundations of what is termed the Frank–Starling law of the heart. This law states that "Within physiological limits, the force of contraction is directly proportional to the initial length of the muscle fiber" (Wikipedia article on Otto Frank, accessed 4-2020).

Translated into English with commentary by Carlton B. Chapman & Eugene Wasserman, "Translators note in relation to a Special Article 'On the Dynamics of Cardiac Muscle' by Otto Frank," American Heart Journal , 58 (1959) 282-317.