I feel that each time I stumble upon fitness advice it's just throwing advice around without having any solid basis at all. It seems that it most often has its root at personal experience and sometimes experience from training others, leading to highly conflicting statements depending on the sites you visit/book you read.

While I don't think empirical knowledge is bad all around for this field, it would be very refreshing to have scientific sources and references to back these statements.

Does anyone know a site or book that at least tries to work more scientifically and states sources?