What can be used to compare changes from one period to another?

The answer would be true. hope this !

People who utilizes the progression principle will ensure their exercise program increases in frequency, intensity, time, and type. the changes need to happen gradually in order to ensure they make gains in their fitness program. a person who doesn't utilize the progression principle can still gain health benefits from exercising, but will not continue to improve in cardiovascular fitness.

Yes, this is very true. specifically causing damage in the  dentrite. 

The average penis size is 27 inches