ExRx.net : Home ExRx.net is a resource for the exercise professional, coach, or fitness enthusiast. It offers evidence based exercise prescription tools and resources including reference articles, comprehensive exercise libraries, and fitness calculators. ExRx.net is a recommended resource in ACSM''s Resource Manual for Guidelines for Exercise Testing and Prescription (5th 6th, and 7th Editions). ExRx.net has also been an NSCA authorized CEU provider since 2008.