The NASM Certified Personal Trainer Certification (http://www.nasm.org/become-a-personal...) and Specializations are developed with NASM's exclusive Optimum Performance Training (OPT™) model, the industry's first comprehensive training system based on scientific, evidence-based research. It takes the guesswork out of program design and helps you produce consistent and remarkable results for your clients. The OPT model was developed to concurrently improve all functional abilities, including flex