I have had many conversations with CrossFitters, and others, about the efficacy of CrossFit programming. As somebody who teaches about physical conditioning at the university level, I am interested in the unorthodox nature of CrossFit and the results it achieves.
While the majority of trainers and athletes easily understand many aspects of CrossFit programming, there is a certain mystique (the infamous "black box") regarding the metcon (metabolic conditioning) workouts. We all know that a "Deadlift 1-1-1-1-1-1-1" WOD (Workout of the Day) is a strength workout and that "Run 10K" (everybody's favorite!) is an aerobic workout.
However, one of my favorite quotes from the CrossFit philosophy is Greg Glassman's injunction to "strive to blur distinctions between 'cardio' and strength training. Nature has no regard for this distinction." But how does CrossFit blur this distinction given that strength/power training and cardiovascular training are at different ends of the power spectrum?
More simply put, when you do "Grace" or "Fran" or "Angie" or even "Linda," what kind of training are you doing? Is it power, strength, or cardio? Can they be combined? To what extent do they overlap? Obviously, they in fact do, and this is one of CrossFit's huge contributions to fitness, but it flies in the face of much of the accepted knowledge in exercise science. How does it work? What are the mechanisms? These are complex questions and the answers depend on many factors.