Ive been on this for about 2 weeks and my strength has increased a good bit but i havnt seen much mass relustls yet because its too early to tell. I am 15 and my shoulder press went from the 50 DB's 8 times to the 55 DB's 8 times, curls went from 40s 9 times to 45 8 times. Overhead single DB ext 25 8 times to 30 8 times. So everything has gone up and i finally reached 300 with my deads!