Articles

To bare or not to bare

For an activity that is supposed to be second in nature, the sport of running seem to be fairly complex, at least judging from the number of possible running styles. The latest of which is that of barefoot running.

Written by Dr. Jason Chia, Consultant, Head of Sports Medicine and Surgery Clinic

I get asked by my patients whether barefoot running is right for them, whether there it will make them faster, what type of barefoot running shoes (I still pause when I say that, if there is ever an oxymoron, "barefoot running shoes" must be one) should one use.

It really isn't helped by the fact that there is relatively little empirical data on this style of running and most of the pronouncements are based on personal likes and dislikes.

Let us first have a look at what empirical data there is, and what might we infer from it.

Is barefoot running is more efficient?

Intuitively, most runners would agree that having less weight on the feet translates into less effort on running. This is true as there are energy cost incurred from moving this extra weight repeatedly on your feet (this has been tested by hanging weights on the feet of runners). The energy cost has been estimated to be twice to thrice as much were you to put the equivalent weight on the trunk. Indeed only some of the studies that compare oxygen consumption (and therefore energy demand) between running barefoot and running with shoes have shown a difference and one has actually shown less metabolic requirement with light weight running shoes1. Why this is the case is not clear but one conjecture is that while shoes do incur a weight penalty, perhaps it helps in the cushioning and support and this might translate into less effort for the muscles, at least up to a certain point beyond which the weight of the shoes outweigh the benefit of shock dampening. Conversely, in studies where running is measured over a short distance (much shorter than most endurance races in practice), comparing net efficiency between barefoot running and running with shoes, the latter is less efficient, as shoes add weight, and though it functions mechanically as a dampener, might also result in less energy transfer to the elastic tissue in the leg or foot, which might be recycled in the next step (but also mean these structures are under less strain)2. In fact, the studies seem to suggest that as we run without shoes, we tend to change to our running pattern to that with shorter strides and forefoot landing, with pre-contraction of the calf muscles to anticipate the impact of foot strike3.

There are other practical considerations involved. Since empirical data shows that runners change the way they run and tend to activate the muscle on the leg when not wearing shoes (presumably to account for the change in impact), whether this increased activation leads to earlier fatigue and then a less efficient gait in a the latter part of a long race (hence off-setting the initial benefits of carrying less weight on the foot) is not known at this stage. Does this mean that we would have immediate race improvement if we change to barefoot running based on the current available data? Not necessarily so. For instance, we do know that for regular runners, the gait that we adopt are often the most metabolically efficient way of running (that our body can manage) and that in the short term, altering the cadence and stride length actually makes a runner less efficient4. This is not to say that one cannot change the running pattern to improve but potentially, it takes time to be retrained in the new gait both in turn of the technique and for physical adaptations) in order to be proficient (and also avoid overuse injuries). Conceptually, it is akin, to climbing down one peak (best performance on running with shoes) into the valley (of temporary poorer performance)  in the hope that climbing the next peak (running barefoot) is ultimately higher when reaching the top.

Is barefoot running the panacea for running injuries?

Conceptually, when running barefoot, the impact of foot strike has to be absorbed and with the absence of shoes to cushion impact, then the "work" must be done by some other part of the body (in the context of landing on the forefoot, the muscles tendon units of the calf and the tibialis posterior, flexor hallucis longus and the flexor digitorum longus). This run counter to the assertion by barefoot running proponents that barefoot running decreases running injuries, since the structures would have to work harder.  Despite the assertions of barefoot running enthusiasts, there are no good studies to demonstrate this but rather there are case studies associated with the switch to barefoot running (but not barefoot running per se)5, 6

The distinction is important as, in overuse injuries, it is often the pace of change (out stripping the adaptative capacity in response to training), not just the absolute volume of training alone, that leads to injury. The practical implications when advising runners who seek to change to barefoot running are three- fold. Firstly, the switch should be gradual, in term of the time given to the change and how fast we remove the support from the regular shoes. So one might reserve barefoot running to the shorter, slower, recovery runs to begin with, and gradually working it into the longer runs. In addition, there are many degree of "bareness" in the minimalist running shoes (sometimes referred to as "barefoot running shoes"), with different amount of shock absorption, stiffness in the shoes and different degrees of drop (how much the deep is raised above the ground versus the forefoot). One can graduate from a shoe with more cushioning / support to one with less over time. Incidentally, the Vibram five-finger shoes appear to result in a similar running pattern as running barefoot, so one can might avoid total "bareness" and save our soles7.

Secondly, it might be advisable to condition the foot in preparation for the change in loading pattern e.g. through eccentric calf strengthening.

Lastly, bearing in mind that barefoot running probably results more transfer of energy to the elastic tissues in the foot and leg, one should take into consideration the presence of pathology in deciding whether to switch. For instance, in the presence of plantar faciitis or Achilles tendinopathy or enthesopathy, it would be advisable to do the switch slowly, if at all.

References

  1. Med Sci Sports Exerc. 2012 Mar 2. [Epub ahead of print] Metabolic Cost of Running Barefoot versus Shod: Is Lighter Better? Franz JR, Wierzbinski CM, Kram R.
  2. Int J Sports Med. 2008 Jun;29(6):512-8. Epub 2007 Nov 16. Barefoot-shod running differences: shoe or mass effect? Divert C, Mornieux G, Freychat P, Baly L, Mayer F, Belli A.
  3. Int J Sports Med. 2005 Sep;26(7):593-8. Mechanical comparison of barefoot and shod running. Divert C, Mornieux G, Baur H, Mayer F, Belli A.
  4. Med Sci Sports Exerc. 1989 Aug;21(4):467-79. Stride length in distance running: velocity, body dimensions, and added mass effects. Cavanagh PR, Kram R.
  5. J Am Podiatr Med Assoc. 2011 May-Jun;101(3):231-46. Barefoot running claims and controversies: a review of the literature. Jenkins DW, Cauthon DJ.
  6. J Sports Med Phys Fitness. 2011 Sep;51(3):401-8. Barefoot-simulating footwear associated with metatarsal stress injury in 2 runners. Giuliani J, Masini B, Alitz C, Owens BD.
  7. J Sports Med Phys Fitness. 2011 Sep;51(3):401-8. Effect of a five-toed minimal protection shoe on static and dynamic ankle position sense. Squadrone R, Gallozzi C.