Yesterday, I interviewed Lee Saxby, the barefoot running expert, and we discussed why so many recreational runners continue to get injured, year after year, despite the millions poured into research and development by the big running shoe companies.
Bare feet work pretty well on the beach
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Lee explained how his research and experience pointed to the fact that the human foot is designed to operate barefoot and not clad in a shoe. So today, I have taken a look at a relatively old study that makes exactly the same point.
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What’s the study?
The study is called Running-related injury prevention through barefoot adaptations, Robbins and Hanna, Medicine and Science in Sports and Exercise, 1985. It’s not easy to sum up the study simply, so bear with me a moment.
The study starts with the principle that the cause of lower extremity injuries in runners is predominantly the impact forces, which have been measured at up to 2.5 times bodyweight. Apparently, this is fairly well-known and accepted.
Next, the researchers note that there is a very high injury rate amongst recreational and competitive runners. (I have actually looked at quite a bit of research on this and concur). However, they note that this has led many scientists to come to the conclusion that this implies the foot is of a naturally fragile and injury-prone nature.
Our researchers disagree. They suggest that this makes a mockery of evolutionary principles and natural selection. How could we evolve a foot that is so fragile and breaks whenever we try and run on it? There are scenarios that would explain this but we should at least test other hypotheses first.
Robbins and Hanna propose that this idea that the foot is naturally injury-prone is linked to the notion that the foot is made up of rigid bony and muscular structures that offer no function in shock absorption. However, the researchers disagree that the muscular structures operate in this way. They suggest that the muscular structures are supposed to offer a great deal of shock absorption but are conditioned to be disfunctional because of disuse.
They hypothesise that the muscular atrophy is due to the foot being prevented from experiencing forces in the way that it evolved to do, because of the packaging in cushioning footwear.
They suggest that the arch of the foot is designed to function as a “dynamic impact dampening structure” by virtue of being controlled by the intrinsic musculature of the foot. They believe that the impact forces are intended to be dissipated to some degree by this arch.
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So what did they do?
Robbins and Hanna therefore took 117 recreational runners and divided them into a control group and an experimental group. The experimental group was asked to build up to doing as much of their training barefoot as possible, beginning with just being barefoot around the house, moving into barefoot walking and finally barefoot running, over a period of four months.
The researchers measured the length of the foot arch in all of the runners both before and after the experimental period. A longer foot arch implies that the foot musculature is inactive and the foot has no innate shock absorption. A shorter arch implies that the foot musculature has a lot more give in it and can mediate forces more effectively.
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So what happened?
The average shortening of the foot arch in the experimental group was 5mm, whereas the control group’s foot arches actually lengthened. When the experiment was discontinued, the researchers found that the experimental groups’ feet gradually returned to their original state.
While this does not show that building up the foot arch prevents injury, it does at least show that wearing shoes reduces the strength of the foot arch and going barefoot increases the strength of the foot arch.
Robbins and Hanna noted that the subjects with the greatest adaptations were those who spent the most time walking or running on irregular surfaces outdoors. So they hypothesise that the key factor for generating the foot arch is plantar sensory feedback. This would suggest that the biggest problem with footwear is that it removes the ability of the foot to experience this feedback. The researchers note that it may be possible to devise shoes that offer some protection but without compromising this function of the foot by minimising the padding on the sole.
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Implications for plantar fasciitis
Well, the researchers propose that plantar fasciitis may be affected by the flattening of the foot arch. They note that in a flattened arch, the fasciia is essentially acting as the support at the heel end of the foot. When the arch is active and supported by the musculature of the foot, the stress on the fasciia is reduced.
Since many incidences of plantar fasciitis occur in populations who stand (in shoes) all day, this is an attractive hypothesis.
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My thoughts
I am always a fan of the idea that the body is a more complex and sophisticated mechanism than we often assume. So I have a great deal of sympathy for an hypothesis that suggests we are doing something stupid by applying an external device to a perfectly evolved appendage. I have also found that spending time barefoot at home and walking barefoot has been both enjoyable and comfortable. Since I don’t run, I can’t really comment on that side of things but I’ll review another study tomorrow that looks at that issue in more detail.
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And don’t forget that it’s better to learn how to run barefoot properly rather than just jump in with both feet, as we found out in my interview with barefoot running coach Lee Saxby yesterday. You can find more information about Lee and his clinics here. And if you are in the UK in mid-December, you can catch one of Lee’s workshops in London. See the details in the flyer below:
