Efficiency & footwear (or lack of)
Alex Hutchinson at Sweat Science recently wrote a post highlighting two studies looking at the effect of a small amount of cushioning on the energy cost of running.
The first study had athletes run in lightweight shoes and barefoot with weights on their feet equal to the weight of the previously used shoes. The results showed that running in the shoes preserved energy while running. Interestingly, they also found that barefoot without added weight was still less efficient than with shoes. The belief is that without the cushioning, the leg muscles must do a bit extra work to absorb the landing.
While there may have been other issues with the study, one is very obvious. No one runs with weights attached to their feet.
To try to remedy this, another study was recently completed. They tested athletes running barefoot and running in lightweight shoes. “As expected, the cost of running was about the same in both conditions — the extra energy burned by the weight of the shoes was almost exactly balanced by the energy saved by the cushioning,” said Hutchinson. Next however, the researchers put 10mm of EVA on the treadmill. This basically placed cushioning under the athlete’s feet without adding any extra weight. When the barefoot runners ran on the cushioned treadmill, they burned 1.91% less energy than when they ran barefoot on a hard surface.
While the studies did teach us something, it does not seem like it will actually change the mind or habits of anyone.
From these two studies we can conclude that a small amount of cushioning saves energy, but the weight of the shoe takes energy, though, not as much as is saved if the shoe is very very light.
So the take away is to simply do what is best for you. Many runners take their shoes off for the pure joy of being barefoot and all of the sensory feedback it gives, not to be a more efficient runner. The increased feedback of being unshod can increase the “feel good” sensation that running gives us! On the other hand, if you wish to squeeze the most speed or endurance out of your running as you can, shoes may be a viable option for you.
Another option is you could mix the two practices. Running barefoot is less efficient. So it is a reasonable idea to include some barefoot running in your training to strengthen your legs. When it comes to those key workouts or races were performance really matters, shoes, and that 1.91% may make a difference.
What factors influence your footwear choices?