Effects of Footwear and Stride Type on Running Economy

Here is is study looking at how running economy differs in habitual minimalist or barefoot runners if they are in minimalist shoes or in a more standard running shoe. 

The researchers found that runners were 2.41% more economical in a minimal shoe when forefoot striking and 3.32% more economical in a minimal shoe when rearfoot striking. 


The conclusion was that these runners in minimal shoes were more economic than runners in traditional shoes. 


However, something bothers me. I quote "We measured the cost of transport (mlO2/kg/m) in subjects who habitually run in minimal shoes or barefoot while they were running at 3.0 m/s on a treadmill during forefoot and rearfoot striking while wearing minimal and standard shoes" 


Bingo. 


The runners tested were habitual barefoot or minimalist runners. That only shows me that we as runners become more efficient at what we most often do. 


Habitually, I...

• do my long runs at a 9-10 minute pace depending on terrain and distance. If I were to deviate from this, going slower or faster, my economy would be negatively impacted.
• have executed the the majority of my training on flat roads. If I go to a trail I use different stabilizer muscles, may land slightly differently, etc. All negatively impacting my economy. 
• use minimalist Skora shoes. Like this study clearly demonstrated, if I was to go for a run in a pair of Brooks Beasts, my economy would take a hit.
• run longer and slower distances. I would be more economical running a marathon than a 5k. 
• run at a 94 steps per minute pace. Any slower or faster and I would be less economical.

Unless I am missing something (please tell me if I am), the study does nothing to show that minimalism/barefoot is better than standard shoes. Only that if you habitually do something, you will become less economical if you make a sudden change.  

Med Sci Sports Exerc. 2012 Jan 3. [Epub ahead of print]

Effects of Footwear and Strike Type on Running Economy.

Perl DP, Daoud AI, Lieberman DE.

Source

Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge MA 02138, USA.

Abstract

PURPOSE:

This study tests if running economy differs in minimal shoes versus standard running shoes with cushioned, elevated heels and arch supports, and in forefoot versus rearfoot strike gaits.

METHODS:

We measured the cost of transport (mlO2/kg/m) in subjects who habitually run in minimal shoes or barefoot while they were running at 3.0 m/s on a treadmill during forefoot and rearfoot striking while wearing minimal and standard shoes, controlling for shoe mass and stride frequency. Force and kinematic data were collected when shod and barefoot to quantify differences in knee flexion, arch strain, plantarflexor force production, and Achilles tendon-triceps surae strain.

RESULTS:

After controlling for stride frequency and shoe mass, runners were 2.41% more economical in the minimal shoe condition when forefoot striking and 3.32% more economical in the minimal shoe condition when rearfoot striking (p<0.05). In contrast, forefoot and rearfoot striking did not differ significantly in cost for either minimal or standard shoe running. Arch strain was not measured in shoes condition but was significantly greater during forefoot than rearfoot striking when barefoot. Plantarflexor force output was significantly higher in forefoot than rearfoot striking, and in barefoot than shod running. Achilles tendon-triceps surae strain and knee flexion were also lower in barefoot than standard shoe running.

CONCLUSIONS:

Minimally shod runners are modestly but significantly more economical than traditionally shod runners regardless of strike type, after controlling for shoe mass and stride frequency. The likely cause of this difference is more elastic energy storage and release in the lower extremity during minimal shoe running.