Being an LSAT dude, I'm pretty skeptical of things I read at first, especially when an author makes big claims.
In a nutshell, McDougall says many foot problems and foot/leg injuries today are a direct result of our footwear. He thinks cushioning and support are bad. They negatively impact the way we run and walk (heel down first = bad), and they make our feet and leg muscles weak so that we can't handle the impact of running this way.
He offers a lot of support for this, but let's look at one particular piece of evidence in isolation.
Runners wearing top-of-the-line shoes are 123 percent more likely to get injured than runners in cheap shoes, according to a study led by Bernard Marti, M.D., a preventative-medicine specialist at Switzerland’s University of Bern.Reminds you of an LSAT Logical Reasoning stimulus, doesn't it? I'll add McDougall's conclusion (in my words): "Therefore, design flaws in top-of-the-line shoes are the cause of these runners' injuries, and they'd be less likely to experience injuries if they switched to cheap no-frills shoes."
Let's think about the evidence and conclusion here and examine for potential flaws.
The evidence regards a correlation (in this case, a direct relationship) between top-of-the-line shoes and a greater number of injuries. Similarly, there's a correlation between cheap shoes and having fewer injuries (than those with top-of-the-line shoes).
Can we conclude from this that the top-of-the-line shoes are actually causing the injuries? It's possible, of course, but there are other potential explanations.
The LSAT's Logical Reasoning section frequently contains arguments where the author confuses correlation with causation (and whenever studies or surveys are presented, there's usually some sort of flaw in their construction or interpretation).
For this reason, I immediately started thinking of alternative explanations:
-Maybe injury-prone and inexperienced runners are more likely to buy fancy and expensive running shoes (hoping the shoes will be a substitute for good technique and actual exercise!)).
-Maybe people who have fancy and expensive running shoes take more risks while running (and thus, it wouldn't actually be the design of the shoes that is at fault - it'd be the runner's fault).
-Maybe people who have fancy and expensive running shoes spend more time running and are thus at greater risk of injury (like the previous alternative explanation, the runner's behavior is to blame for the injuries, not the shoes).
McDougall provides additional evidence
If that one piece of evidence (the correlation) was all McDougall provided to support his argument, I wouldn't take him seriously, given the alternative possibilities.
He's smarter than that, though, and provides dozens of pieces of evidence to support his argument about modern shoes. He also gives additional support for the particular study described above:
Dr. Marti’s research team analyzed 4,358 runners in the Bern Grand-Prix, a 9.6- mile road race. All the runners filled out an extensive questionnaire that detailed their training habits and footwear for the previous year; as it turned out, 45 percent had been hurt during that time.(Source: Born to Run, p171-2)
But what surprised Dr. Marti, as he pointed out in The American Journal of Sports Medicine in 1989, was the fact that the most common variable among the casualties wasn’t training surface, running speed, weekly mileage, or “competitive training motivation.” It wasn’t even body weight, or a history of previous injury: it was the price of the shoe. Runners in shoes that cost more than $95 were more than twice as likely to get hurt as runners in shoes that cost less than $40.
McDougall tells us that Dr. Marti was considering potential alternative causes such as "training surface, running speed, weekly mileage," and "'competitive training motivation.'" Of course, perhaps there's something else Dr. Marti failed to consider, but he seems to have considered, and dismissed, some of the biggies. In short, Dr. Marti's argument appears to be pretty good so far.
However, there are still other areas to attack in this study now that we have more information.
Is 4,358 runners a large-enough sample size? We might want to think about how big the running community is in general.
Is the previous year enough of a period to look at? Perhaps we want to go back further in time.
What sort of runners go to the Bern Grand-Prix race? What sort of runners run a 9.6-mile road race? Maybe racers in general aren't representative of the running population.
You won't always have to go this far into your analysis of a particular argument, but it's good to be skeptical. Always think about alternatives. Think "what if?"
As for me, I'm enjoying running barefoot. Let me know if you want to go for a run in Central Park sometime!
Photo by mikebaird / CC BY 2.0