All of the following factors normally increase the length of the ventricular cardiac muscle fibers except

Heteromeric regulation of stroke volume includes factors that regulate cardiac output as a result of changes in cardiac muscle length. End-diastolic volume has a role increasing the length of cardiac muscle fibres. .Venous return and ventricular filling are the factors affecting EDV. Venous return is affected by skeletal muscle pump, venous tone, negative intrathoracic pressure due to its suckinv effect, lying down posture than standing posture, increased blood volume. Ref: Textbook of medical physiology by N Geetha, 2nd edition, page no. 169,170