Preload vs. Afterload

Preloadverb

(transitive) To load in advance (used especially in reference to software installed on a computer prior to sale).

Preloadverb

To drink (cheaper) alcohol at home before going out socially.

Preloadnoun

The end diastolic pressure that stretches the right or left ventricle of the heart to its greatest geometric dimensions under variable physiologic demand.

Afterloadnoun

(physiology) The load on a working muscle from a constant opposing force

Afterload

Afterload is the pressure that the heart must work against to eject blood during systole (ventricular contraction). Afterload is proportional to the average arterial pressure.