Possible Insight

I wanted to like Little and McGuff’s Body By Science. The fact is that most people, from novices to professionals, follow exercise programs that at best waste their time and at worst are counterproductive. BBS does do a good job of pointing out these areas.  However, the conclusions it draws about what people should do instead are also not well supported by the science.

I get the feeling that Little and McGuff started with a pre-conceived exercise ideology and then went hunting for science that supports it. I would sum up this ideology as: less is more, weight machines are better than free weights, cardio is bad. The actual science on this is strong, non-existent, wrong.

What really rubbed me the wrong way was how they evangelized their specific program . I categorize the objectionable evangelical tactics into three categories: blinding readers with science, selective application of principles, and just plain wrong.

Blinding Readers with Science

BBS contains discussions of physiology (primarily cell biology and endocrinology) that one would find in a mid-level college text. Two problems.  First, the vast majority of readers simply won’t understand it. Second, it’s misleading because it looks at physiological features in isolation.

My guess is the first problem is intentional. The authors want to overwhelm readers so they will believe the book’s conclusions: blinding them with science. My guess is the second problem is inadvertent. The authors sincerely believe they can draw causal conclusions by analyzing narrow subsystems: ignoring complex systems effects.

There’s a lot of discussion of various endocrine circuits and how the fact that a particular pathway exists implies that optimizing the execution of that pathway will lead to the desired macro results. The problem of course is that the endocrine system is actually a complex system of interdependent, nonlinear circuits so it’s difficult to predict the macro results of changes to a pathway or group of pathways.

Selective Application of Principles

Having tried to get readers to accept them as experts, Little and McGuff proceed to selectively apply various principles.  Many uninitiated readers probably buy these arguments as objective applications of scientific results. Nothing could be further from the truth.

The prime example is the principle of specificity: that whatever exercise you perform trains your body to perform that specific activity. The first problem with BBS is that it treats specificity as a binary property, either the exercise is exactly like the target activity or it isn’t. Of course, this can’t possibly be true.  Running on a track at Stanford is similar enough to running on a track at UCLA to hold athletic competitions. Running on a track is similar enough to running on a flat road to allow track runners to run very well roads. Running on a flat is similar enough to running on a hill to allow flat runners to run fairly well in the hills. There is a spectrum of specificity.

Of course, specificity is multidimensional.  There is tempo as well as mechanics. Will a marathon runner or a sprint cyclist win in a 50m foot race?  Good question.  I’d give even odds.  But I’d go with the runner at 400m.  And either one would smoke a sprint swimmer at 50m.

Now, Little and McGuff use the principle of specificity to argue against cardio. Cardio won’t help your practical endurance more than weightlifting because they put the same strain on the cardiovascular system.  If you want endurance for a sport or recreational activity, you should just do that activity. Huh? A lot of activities involve running of some sort so it seems like hitting the track or the treadmill might be a good idea for general fitness.

Of course, they fail to apply the specificity principle to the question of free weights versus weight machines. They argue that free weights are potentially more damaging to the joints and no better at building muscle. But doing a free weight hammer curl is really similar to picking up a gallon of milk and a free weight deadlift is really similar to picking up a box. Much more so than the machines targeted at those body parts. Funny, no mention of that.

Just Plain Wrong

BBS also supports its exercise ideology with assertions that are just plain wrong. The most egregious is that you shouldn’t do cardio because all endurance adaptations occur in the muscles. So if you just lift weights then you’re getting the same benefits as doing cardio that works the same muscles.

Hmm. Stroke volume, blood volume, blood pressure, lung capacity, and pulmonary diffusion are just some of the systemic adaptations that occur from aerobic exercise.

And contrary to the assertions of the authors, cross training does improve performance (presumably due to the systemic effects).  Not as much as additional training in the specific activity, of course. Running seems to be the most beneficial cross training discipline (see here and here).  So again, it seems like a good idea to hit the track or treadmill.

Now, I’m used to exercise books and articles that are full of misinformation. But this book had such potential that it bothered me much more than most.