The National Academy of Sports Medicine (NASM) is one of the largest certifiers of personal trainers, known for its Optimum Performance Training (OPT) programming model.
NASM's public listings describe the NASM-CPT as an NCCA-accredited certification requiring a proctored exam, CPR/AED qualification and recertification every two years through continuing education. NASM also publishes specialisation credentials — corrective exercise (CES) and performance enhancement (PES) among them — which are add-ons rather than stand-alone trainer certifications. NASM-certified trainers appear in the USREPS registry, where the credential's current status can be checked.