Loved this book. I've been "lifting weights" for years without really seeing any results. Now with the X3 and variable resistance (as described in this book) this scrawny guy has been able to put on 10 lbs of muscle. Dr. Jaquish wrote this in a way that covers hundreds of research studies but makes the science approachable. I'd highly recommend this book to anyone, male or female, looking to build muscle and get stronger without risking injury.