Final answer:
The intensity needed to cause excitation when the pulse duration is maxed out is known as chronaxie.
Step-by-step explanation:
The intensity needed to cause excitation when the pulse duration is maxed out is known as chronaxie. In muscle physiology, chronaxie refers to the stimulus duration required to elicit a response at twice the rheobase current. It is a measure of the strength-duration relationship of a muscle fiber. When the pulse duration is maximized, a higher intensity is needed to reach the threshold for excitation, which is characterized by the chronaxie.