runderun wrote:
Running economy is measured by your oxygen intake. So you basically use 4% less when running in the Vaporflies. This is compared to running in a standard racing flat - in one study I know they used the Adidas Adios as a baseline and in another it was the Saucony Endorphin Racer.
All of the papers I've read on this issue are well-designed studies, not your L'Oreal "87 of 102 women agree" kind of junk researvh.
As to how this translates to time: 4% improved economy is about 2-2.8% improvement in time. For an elite marathoner, around 1m30s-2m.
How fast are your elite marathoners? Even for someone who can run a two-hour marathon in the baseline shoe, a 2-2.8% reduction in time would be 144- 201.6 seconds, or 2m24s-3m21.6s. For a 2:10 marathoner, the time reduction would be 156-218.4 seconds, or 2m36s-3m38.4s; for a 2:20 marathoner, the reduction would be 168-235.2 seconds, or 2m48s-3m55.2s. Also, although I could see it in other contexts, It's not immediately obvious to me why, in the context of marathon running involving shoe models that may vary by perhaps a couple of ounces, a 4% increase in economy would typically produce only a 2-2.8% improvement (reduction) in time. With this particular type of shoe as compared with a more conventional racing flat, I would expect the percentage difference in time (not just the absolute time difference) to increase as the race distance gets longer, approaching and eventually surpassing the difference in economy. But obviously, that's ultimately a highly specific empirical matter; the human body is too complicated for purely armchair calculations and crude laboratory experiments,