During which phase does no relaxation of the tissue occur?

The phase during which no relaxation of the tissue occurs is during the interpulsed intervals. In this context, the interpulsed interval refers to the time period between the pulses of electrical stimulation. During this interval, the electrical current is not applied, allowing the tissue to start relaxing from the previous stimulation. However, since relaxation does not occur continuously through this duration and instead requires distinct periods of rest, it is important to denote that the stimulation process actively influences the tissue's activity.

In contrast, during continuous current or direct current application, the current flows consistently without interruption, leading to prolonged activation of the tissue. This constant stimulation can result in fatigue and may not allow for adequate relaxation between stimulation events. Alternating current also creates periods of stimulation, but since it alternates in direction, it typically allows for some physiological response that may facilitate relaxation at certain cycles, even if only briefly.

Therefore, the absence of relaxation is effectively illustrated during the distinct phases of stimulation and rest, particularly during the interpulsed intervals where no electrical current is applied, indicating that tissue recovery processes may begin but do not fully manifest until subsequent stimulations are halted.