Systolic pressure represents:

Systolic pressure is defined as the peak or highest pressure within the arteries during the heart's contraction phase, known as systole. During this phase, the ventricles of the heart contract and pump blood out into the arteries, resulting in an increase in pressure. This measurement is crucial because it indicates how well the heart is functioning and how effectively blood is being circulated throughout the body.

Understanding systolic pressure is vital in assessing cardiovascular health, as elevated levels can indicate conditions such as hypertension, which increases the risk of heart disease and stroke. In contrast to this, the lowest pressure in the arteries occurs during diastole, the phase when the heart is relaxed, and thus does not relate to systolic pressure. The average pressure during the heartbeat would not accurately represent the peak pressure measurement, and diastolic pressure specifically refers to the pressure during the relaxation phase, not systolic pressure.