|Picture from article Scientific Reports|
Each time we land on our arches when we run, energy is stored in our arches. This is free energy that doesn't require anything to activate. The researchers wanted to measure wanted to find out specifically how much energy is lost if they restricted the arch with orthotics.
|Orthotic that was used|
In order to have a baseline measurement, the runners ran in just the shoes (that were similar for all runners, pictured below) first followed by the same shoes at the same speed while testing the home made orthotics.
|Picture from Scientific Reports|
The runners tested the orthotics while walking as well as running.While walking, there was virtually no difference in energy expenditure. However, while running significant energy loss occurred.
In the orthotics that blocked all compression, researchers measured an energy cost of six percent (or less efficient by six percent) while the orthotics that allowed for 50 percent compression lost four percent.
Before you throw away your orthotics (if you're wearing them) the authors suggested don't throw them out yet as many runners get custom made insoles to prevent injury. They felt this is more important than saving energy without the orthotics. In fact the authors were very diplomatic and said that "We don't want to say orthotics are good or bad."
Likewise, if you are considering wearing orthotics (but may not need them), then maybe you shouldn't especially if you wanna run faster.
Stearne SM, McDonald KA et al (2016). The Foot's Arch And The Energetics Of Human Locomotion. Scientic Reports 6, Article number: 19403. DOI: 10.1038/srep1940.