Final answer:
A good PT can manipulate the intensity of a resistance training program by increasing weight, adjusting repetitions, or altering rest intervals; changing the exercise is not a method of manipulating the same exercise's intensity.
Step-by-step explanation:
A good PT (physical trainer) can manipulate the intensity of a resistance training program without the need to change the exercise itself. The ways to achieve this increased intensity include, but are not limited to, increasing the weight (slight or huge increase in resistance), adjusting the number of repetitions, and altering the rest intervals between sets. Such adaptations are essential as the muscles require progressively heavier loads to grow in size and strength. However, changing the exercise altogether does not adjust the intensity of the same exercise; it introduces a different type of stimulus.