For years runners have debated the merits of what they wore on their feet. Some recommended running barefoot. Others argued that shoes’ spongy soles helped runners cope with the rough concrete of roads and trails. Others believed that the running shoes were somehow amplifying the body’s natural spring-like steps.
A new study, conducted by researchers at the University of Queensland, outfitted 16 volunteers with intramuscular electrodes that recorded the muscle activity in their feet. The wired volunteers ran—both barefoot and with running shoes—on a treadmill equipped with force sensors. According to Ars Technica science writer Beth Mole the researchers “paid particular attention to the runners’ muscles in their longitudinal arches, which have a natural spring-like action, bending as the foot lands and recoiling on the lift.”
When the study participants wore shoes, their arches did not bend as much. In fact they bent about 25% less than when the runners ran barefoot. This finding appeared to support those in favor of running shoes who believed that good shoes cushion each strike of the foot.
Skeptics disagreed, claiming that arch support diminishes the use of the muscle which leads to muscle weakness and eventual atrophy. Not so. Researchers found that arch muscles were working harder when runners wore shoes than they did when they were barefoot.
According to Mole, to make sense of their data, the researchers drew on results from experiments in which researchers stimulated muscles with electrical zaps and found that the muscles in the foot work as a unit, not individually. They hypothesized that with arch support from the shoe, the foot muscles had to work harder to match the extra stiffness in the system. They found that the best scenario was when running shoes act as a spring that works in concert with the runners’ feet. The shoes stiffened the foot’s natural springiness, rather than acting like an independent shock absorber.
The researchers in this study are aware that their work did not produce the final answer on how best to run. Mole reports that the data hints that running shoes have benefits. Maintaining leg stiffness during running is something bodies innately try to do. This may be because we need leg stiffness to keep our balance and control our center of gravity. Because running shoes provide some arch stiffness, foot muscles must work harder, boosting overall stiffness.
The study and researchers’ conclusions are reported in the Journal of the Royal Society Interface.
