Final answer:
The typical normal response to exercise on an ECG is an increased heart rate, observed as a shorter time interval between QRS complexes, not T-wave inversion, ST-segment depression, bradycardia, or an increased PR interval, which are often signs of pathological conditions.
Step-by-step explanation:
The normal electrocardiographic (ECG) response to exercise includes increased heart rate, which can be noticed by a reduced time interval between QRS complexes on an ECG. Among the options provided, the correct answer is T-wave inversion. However, it should be noted that while T-wave inversion may occur during exercise, it is not considered a 'normal' response and is often seen in ischemic conditions. Thus, the more typical and 'normal' response to exercise is none of the given options; a normal response would typically include an increase in heart rate rather than ST-segment depression, bradycardia, or an increased PR interval.
An increased heart rate during exercise is due to the sympathetic nervous system's response to physical activity, leading to faster depolarization rates and therefore a reduced interval between successive QRS complexes. In the context of an ECG, this translates to a shorter R-R interval, exhibiting a normal adaptation of the heart to increased physical demand.