Hands down The Biomechanics is the way to go. I have been NASM since ’99 and it is great but I really believe in Justin Price. His methods are very simple and easy to understand. The difference in the two programs is that The Biomechanics is centered around clients in chronic pain and doesn’t outline a weight-loss or performance enhancement type programing the way that NASM does. So it probably really depends on who you service, but for ease of education, I pick The Biomechanics.
I do not think you can go wrong with either. I have my CES through NASM and thought it was an excellent and thorough program. I did not find it to be centered about weight loss or performance enhancement, I thought it was geared to every day people with imbalances and/or chronic pain. That said I have viewed many continuing ed videos by Justin Price and agree with Jeremy, that his methods are sound and easy to understand. I would weigh price and convenience to help you decide.
I also have the CES through NASM. I found it to be an excellent course. You can use the text book, online text book, and online videos. The videos demonstrate how to perform an assessment and clearly teach you what to look for. Weight loss and performance enhancement is not part of this course. There are separate NASM courses which focus on those topics. Having the NASM CES has helped me expand my base of clients. I am sure the Justin Price course is also very good, but as I remember it is quite expensive. I think it was over $2000 and I paid less than $600 for the NASM CES.
I have the NASM CES cert. I think that it’s great for integrating corrective exercise into your clients program. I thought that the course was very thorough and simple to understand. Just as Denny mentioned, the course includes a variety of materials in addition to the text that clearly demonstrate how to make practical use of the assessments. The course also includes a ton of pre-programed workout charts for all the movement dysfunctions that are covered.
I initially tested this stuff out on myself as I was a little gunked up in a few areas. I can vouch that the program works and is worth every penny.