In the last decade, there has been a growing body of people who try and emulate our ancestors’ diet and lifestyle. One aspect that appealed to many was bare-footedness. However, some of these people began to realize that while being barefoot in the house was enjoyable, going outside only to step on rocks and stub toes was not. Thus, the minimalist shoe was born.
Running, specifically, is an activity in which many persons have ditched their shoes. In fact, a recent survey of 364 recreational, 380 competitive, and 41 elite runners who participated in races ranging from 5km to full marathons revealed that 75% were at least interested in barefoot (BR) or minimalist (MR) running, while just over 50% had actually switched away from shod running (SR). The main reason listed for switching away from SR was injury prevention, and some research does suggest that the change in running kinetics (heel strike vs. non-heel strike) may protect the feet and legs from some of the impact-related injuries now experienced by a high percentage of runners.
Another reason for making the switch is the proposed improvement in running economy. Higher running economy basically means that less oxygen is required to run a certain distance, which is critically important in aerobic sports such as running. But reports on this are mixed, which is what led researchers from Hong Kong Polytechnic University to synthesize the available literature into a meta-analysis.
Before analyzing the data, however, what is a “minimalist” shoe? These definitions will obviously influence the results and, as such, were defined in the following manner:
- BR was complete barefoot running or running with socks
- MR was using footwear that weighed ≤8 ounces, had a heel-toe drop of ≤5 mm, and had no additional cushioning padding and artificial support
- SR was everything else
Ultimately, a total of 13 studies with 168 participants were included. Since some studies reported the habitual running type of the participants while other didn’t, about 50-73% were experienced with barefoot running. The metabolic cost of running was similar with BR and MR, but both had lower oxygen consumption than SR. It is also worth mentioning that the most commonly used minimalist shoe was a Vibram Fivefinger.
The researchers offer three explanations for the reduced oxygen consumption. First, it has been shown that elastic energy that is released from the arch is reduced in shod running. Second, BR and MR are associated with shortened stride length and increased cadence, which leads to less ground time and thus less friction. Finally, more oxygen is necessary because shoes weigh more.
The current findings support the notion that the running economy of BR and MR are statistically more efficient than SR. Previous work has indicated that a 1.7% drop in the oxygen cost of running may lead to an improvement in running speed by about 7.3 meters/minute. Thus, the oxygen cost saved in the current meta-analysis would translate to an increase in running speed of 1.73-1.59 meters/minute, which may indeed enhance performance when looking to long-distance events. That said, all the studies of the current meta-analysis were conducted in on a laboratory treadmill, so the application to real running remains to be determined. Additionally, oxygen consumption may actually be greater when individuals perform unfamiliar tasks, thus making it possible that runners not yet adapted to shod running may initially perform worse.