Program design by natural bodybuilding and powerlifting champion Layne Norton. P.H.A.T stands for Power Hypertrophy Adaptive Training. Program is split up into a 5-day split with 2 days being dedicated to powerlifting and the other 3 being utilized for hypertrophy training. This a high volume approach to training and is not for that faint at heart. I have seen great gains with this training style and would highly recommend it to anyone.