Starling’s law of the heart

Starling’s law of the heart

Starling’s law of the heart states that the force of contraction of the heart muscle is directly proportional to the initial fibre length. When the heart muscle fibres are stretched, the force of contraction increases, to a particular limit. This helps the heart to deal with an extra load.

It is the volume of the heart which determines the force of contraction. Increase in muscle fibre length increases the force of contraction upto a certain level. Beyond this level, further increase in the volume of the heart produces deterioration of cardiac output. 2.2 microns is the critical sarcomere length at which there is optimal force of contraction, due to good overlap of actin and myosin filaments.