Carbon shoes are not going to replace training. Get your training down, get your mechanics, and then carbon shoes will add that 2 to 4%.

The lab result is real. Carbon-plated, high-stack shoes improve running economy by about 4 percent against the old racing flats, and that finding has been replicated to death. I am not a shoe skeptic. I own more than 30 pairs.

But 4 percent of what? The gain is a percentage of the engine you already built. Four percent of a well-trained aerobic system is minutes. Four percent of three easy runs a week is nothing you will notice at your goal race, and it cost you 250 dollars.

So the order of operations matters. Training first. Mechanics second. Shoes last. The plate rewards a runner who loads it the way it was designed to be loaded, which is why the same shoe reviews as magic for one runner and as a wobbly waste for another.

How I run mine. Every race shoe gets a 2 to 4 mile break-in before it races, never more, because the foam is the expensive part and it has a lifespan. I get roughly 150 miles from a race pair before the pop is gone. My actual rotation, with the miles and the verdicts, is in the shoe picks.