While I have spent a great deal of time assessing the arguments and the literature concerning the true function of the foot and differences between shod and unshod postures, gait, and movement I haven’t really addressed the injury realm extensively nor have I shared with you Boddicker Performance’s assessment set that we use to check preparedness for barefoot running.
It is commonly asserted that barefoot running isn’t a good idea based on the evolutionary thought process because our landscape is rife with modern objects that were not around when Cousin Caveman was unshod on the plains. While I agree with this, it does not provide enough of an argument to completely rule out barefoot training.
Some further assert, then, that external loading forces are greater in unshod conditions and lead to greater impact loading. Unfortunately, this isn’t entirely true and the research is equivocal on the matter. Additionally, impact force is not a strongly supported biomarker of injury potential in running. Provided ample recovery time and nutrition is given to allow Wolff’s Law to do its thing, it may result in even stronger tissues. Interestingly, there seems to be an application of the same law in shod populations in reverse. Those habitually shoe-wearing people demonstrate decreased robusticity of the hallux and a number of other toes, presumably as a result of a lack of use (Ruff, 2006). Trinkaus, after studying a number of shod and unshod populations reached similar conclusions because of restricted lateral movement and superior/inferior movement when wearing shoes.
One may also note that barefooted, while impacts may be slightly greater, the forces are much more evenly distributed across the entire plantar surface leaving less pressure per unit area (likely due to behavioral modification from the “Ouch, my heel contact hurts without cushion. Time to find a better way.” law). The foot position at ground contact in barefooted locomotion also transmits forces to yielding musculature allowing the active restraints to take stress away from passive tissues leading to better attenuation of force. In barefoot running, toe splaying, ground gripping, and the formation of a more stable base are accommodations to prevent too much stress in one place that will lead to tissue overload.
In populations that have co-existing shod and unshod populations, Robbins and Hanna show that the shod populations show much greater frequencies of lower extremity injuries compared to the habitually unshod. The authors further assert that running-related injuries to the bone and soft tissues are significantly lower in developing countries, where shoes are worn infrequently (1987). Zipfel and Berger also confirmed this finding in their own research (2007). What’s more is that Robbins demonstrated that those who spend more money on their running shoes are going to experience a greater likelihood of running related injury than those who spend much less (1991). He theorized that this is presumably because the padded heel creates “a perceptual illusion is created whereby perceived impact is less than actual impact, which results in inadequate impact moderating behaviors and subsequent injury.” Like we discussed last week, the afferent impact on locomotion and movement is critical and putting something in the way generally limits perception and subsequent reactions negatively. Remember to respect the nervous system.
Anthropologists have done fascinating research on habitually unshod populations, and have reported a number of interesting observations. Including wider spread toes in barefoot people, thickened glabrous skin on the surface of the foot sometimes a centimeter thick, and natural arches.
If this is the case, then, ideally it will open up your mind to begin to consider barefooted training with a bit more seriousness. However, an immediate transition to barefooted running for 100 miles in a week is a bad idea because if you are reading this, odds are quite strong that you are not a member of habitually barefoot clan. A sensible progression should always be undertaken when making the transition to minimize undue harm from years of maladaptation, and I will soon share with you my approach.