Eric Cressey had an interesting tidbit in his newsletter recently:  to the throngs of athletes, pro and weekend, who besiege him daily with questions about whether this or that fitness protocol is useful, healthy, or effective, he says, essentially, "it always depends."

Cressey and his charges approach fitness programming rather like a physicians working with patients:  not with blanket recommendations but with highly individuated plans tailored entirely to each person who walks in their door.  So virtually no fitness protocol is applied uncritically to everyone.

The main lesson here is that the rules--such as they are--are highly changeable and highly context-specific.  Ask three trainers the best way to lose weight, for example, and you'll get three answers--not because any of those trainers is dumb or ill-informed, but because many systems are effective and the science--the hard data--about what works best is sparse and diffuse. 

But perhaps the most important factor in determining the effectiveness of a given fitness system for any single person is the human one.  A few weeks ago I wrote about the results of a study conducted by Alwyn Cosgrove and John Berardi comparing the relative benefits of a strength-training protocol combined with either a steady-state cardio protocol, an interval protocol, or a suspension-training protocol. 

The dropout rate was astronomical for the steady-state group (around 80%), fair to middling for the interval-training group (50% or so), and relatively small for the suspension-training group (30% or so). 

In the real world, then, the effectiveness of these programs would, to a large extent, be determined not by calories burned per hour or by elevated BMR rates, but simply by the taste of the participants:  how FUN did they find the program?  If four out of five people who embark on a steady-state cardio program can't stick to it for a measly eight weeks, even when they're being monitored by two of the top fitness pros in the business, well, that probably tells us all we need to know about steady-state cardio:  most people can't stomach it.  So even if it's proven effective--which the study results bore out--the human factor says that it's probably not the right choice.  The best program in the world only works if you--you know--DO it.

As much as I love knowing the best this and that for this and that training effect, I'm therefore willing to accept a little inefficiency, and even take on a little risk, if a client loves a given exercise or activity, rather than tell them they shouldn't be doing it and try to substitute in my own methods that might be maximally efficient but dead boring to someone who's wired for something else.