This turned up in my alerts today. It is an undergraduate thesis from Fort Lewis College¹:
The Acute Effect of Heel to Toe Drop on Running Economy.
Brown, Harrison and Silva, Robert (2013). Undergraduate thesis, Fort Lewis College.
The purpose of this study was to assess how the running economy of experienced runners was affected when wearing 4mm and 0mm heel to toe drop shoes as opposed to regular running shoes. Previous studies have shown that barefoot running and running in lower heel to toe drop shoes increases running economy (Squadrone & Galozzi, 2009). The participants (n=23; 18 male and 8 female) were subjected to 3 separate tests that were each 20 minutes. The tests were performed within 90 minute, the order randomized. During the first test, the subject ran for 20 minutes at a speed they would run at for 1 hour. During the second and third test, the subject ran at the same speed in their randomly chosen shoes. Gas analysis was used to measure VO2 in kilograms and measurements were taken one time per breath for 20 minutes with a Vacumed mini-CPX. Using one way repeated ANOVA, results were not significant (p>.05). The results of this study show that there was not a significant difference in running economy between running with 4mm or 0mm heel to toe drop shoes and running with regular running shoes. This study was examining acute changes in running economy, however it is recommended that further research examine long term changes in running economy
They compared college runners in their usual shoes and also the 0 and 4mm drop New Balance Minimus running shoes and they measured oxygen uptake and found no differences between the 3 conditions.
The study does suffer from the usual constraints that go with an undergraduate type project but was still a pretty impressive effort. There are issues in this and other running economy studies about the acute vs habituated intervention. This just adds to pot of mixed results in studies on running shoe conditions and running economy. We are no further down the track on resolving which is the most economical way to run, but I suspect it is going to be very subject specific.
As always, I go where the evidence takes me until convinced otherwise.
¹This is the second undergraduate project from Fort Lewis College that I have commented on. the other one was this: Vertical Ground Reaction Forces Produced in Shod Running vs. Barefoot Running