According to the principle of progression, exercise programs should gradually become more difficult over time.

It's TRUE.

Explanation:

      There comes a point when doing the same workout in the same way every time doesn't make you feel you are exercising. To change this, you can base your workout on  the principle of progression. That is, you have to build an exercise program designed to improve your physical fitness by gradually increasing the difficulty of your routine. In this way, your will be doing harder exercises making changes in repetitions, duration, or speed. You have to progressively challenge your body so that your work out pays off.

i think she would gain 18 grams