1. Barefoot running transmits a less violent shock to the runner at foot strike because it distributes the impact with the ground over more time.
Rebuttal: Barefoot running doesn’t reduce impact force, forefoot striking reduces impact force.
The argument that running barefoot reduces shock is largely based on the following three graphs, which show that running barefoot results in a softer, more gradual impact with the ground. The uphill slope at the start of each peak represents the impact loading rate, or the shock experienced by the runner at foot strike. A steeper slope means a more violent impact.
This first graph (below) shows the vertical impact force when heel striking in a running shoe.
The spike before each peak is typical of a heel striking gait and is even more dramatic when heel striking barefoot.
This second graph (below) shows the vertical impact force when running barefoot with a forefoot-striking gait.
When striking with the forefoot while barefoot, the initial spike is gone and the full load of 2.5 times the runner’s body weight is applied more slowly.
This third graph (below) shows that although running in shoes reduces the impact force during foot strike when heel running in shoes compared to heel running barefoot, forefoot striking while barefoot creates a much smaller initial impact force than the other two conditions.
Most runners new to barefoot running quickly learn to strike with their forefoot, so it seems logical that running barefoot would reduce injury when compared to running in shoes because this initial shock is so much less.
This chart is not only a comparison of barefoot to shod running, but it is also a comparison of forefoot to heel striking. To complete the chart, it needs a final data point of a forefoot striker in shoes. This argument promotes forefoot running, not barefoot running.
The dramatic change in initial impact force did not come when the subjects switched from shod to barefoot; it came when they switched gait pattern from heel striking to forefoot striking. There is no reason to believe forefoot striking in shoes would result in an impact force more similar to the “shoes heel” column than the “barefoot forefoot” column.
One of the studies cited declares that running in shoes promotes heel striking, so therefore forefoot striking in shoes isn’t a practical option. But the article then goes on to clarify that a prolonged adaption or break-in period is needed to run barefoot without excessive soreness or injury. So why not use that period to learn to strike somewhere other than the heel while wearing shoes? Shoe brands are now designing shoes specifically to facilitate fore- and mid-foot striking by building them with a smaller height differential between the toe and the heel. Although some shoes certainly can promote heel striking, there are plenty of alternatives that help facilitate mid- or forefoot striking.