An example of change in the intensity training principle is adjusting the duration you hold a stretch or perform a cardio activity kind of exercise you perform level of effort you use number of days per week you participate in a physical activity

level of effort you use

Explanation:

Intensity in physical exercise is related to the power that your body is capable of withstanding the physical exercise in question. So intensity exercises usually test the power of your body through the effort you use to perform the exercise. Thus, we can state that the intensity is related to the capicity that your body has to perform an activity at a given time, so we can conclude that an example of change in the principle of intensity training is the level of effort you use .