Lauren wants to strengthen her core and lower back muscles. she currently performs three sets of 6 inch holds for about 10 seconds on each lift. she decides to increase to 15 seconds per lift. this type of change is an example of a

The answer is organisational websites.

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)