The only thing with Joe Friel's book is that is really hard to understand. His communication skills leave a lot to be desired. It was disjointed and overly complex and as a scientist I read and write scientific journal articles in immunology. So it isn't as if physiology is a tough subject for me.

I would go with one of Chris Carmichael's books instead. Joe Friel also doesn't really have any training plans in the book. It was designed for a person to understand exercise physiology and then design your own training plan.