Paul Chek states in part 2 of his Program Design audio clinic that in order to increase anabolic responses after a workout, your sessions should only last 30-50 minutes maximum. Does this include the warm up and stretches? When adopting this theory, would you still take a day's rest between workouts? If so, would that rest mean complete rest (e.g., no cardio)? What if this were a boxer trying to maintain muscle as opposed to a strength athlete?
Training Time Per Workout
When determining training time, all stretching and exercise related warm-up activities are not considered part of the actual training volume. Training time begins when the individual/athlete is actually performing what are traditionally referred to as "work sets." Care must be taken, though, when there is a need for extensive pre-workout stretching and/or extended warm ups, to make sure blood sugar levels do not drop. If they do, there is a pronounced catabolic response to the workout. I have my athletes eat about 30 minutes before they begin their pre-training routines; some athletes do better with 45-60 minutes while those lifting heavier weights are typically protein types and do very well on about 30 minutes and spend about 30 minutes in preparation.
The use of rest is quite a complex topic, and I know several variables to answer the question optimally. This is covered in detail in both my "Program Design" and "Advanced Program Design" correspondence courses. A general answer based on your question is yes, there is scheduled rest days between workouts, allowing optimal time for an anabolic response by the body.
I personally very rarely use cardio as you are likely to be referring to it unless I'm training an endurance athlete, and if I do, they do that work as sport specific training (e.g., runners run, bikers bike, swimmers swim). Cardio responses are movement pattern specific, and therefore, any useful cardio for an athlete must be pattern specific. In addition, there is a significantly greater catabolic response by the body with cardio than with resistance training, which is why those athletes doing it regularly become smaller, skinny in fact. Most people use cardio because they want to burn extra calories, yet it is far inferior to resistance training. I think you would benefit from reading my article about Cardio Training on PTontheNET.com.
The use of active, passive or total rest methods, again, is very specific to individual needs. A boxer trying to maintain muscle mass would use resistance training as part of a carefully periodized program and would be performing multiple workouts in one day. I was the trainer of the US Army Boxing Team in 1984-1986 as well as the World Military Championship Team in the same period. I was also a fighter on the team and am very familiar with such methodology. I would have some fighters train either first thing in the AM or in the late afternoon depending on their overall boxing volume and time of season.
Most trainers overtrain people, having almost a fear of rest. It is very important to remember that the under-trained athlete will always out-perform the over-trained athlete, which becomes very evident in a boxing ring! If you assess biomotor abilities, as I describe in "Advanced Program Design," you will know exactly what your athlete/client needs, and you will be able to properly periodize all acute and chronic variables. Until programs are being designed based on comprehensive assessments, trainers and coaches are merely following the sheep or doing what most know as fad training. This is very easily seen in sports like boxing and sprinting, for example, where the way people train changes every time a new champion is crowned. Everyone was training like Ben Johnson, then Michael Johnson, and in boxing, you will have seen everything from Mohomad Alli to Mike Tyson and all variations in between. Why? Lack of confidence in individualization of training programs and no assessment!
I'm sorry if I can't be more specific. Program design is an exquisite science, and general questions only result in general answers. That said, I think you will get some clinical pearls from this transaction.