Shod vs. Unshod : What the Lieberman-Harvard study really said.
Shod vs. Unshod : What the Lieberman-Harvard study really said.
Thanks to OwenAnderson of Educatedrunner.com for this excellent article.
If you are paying attention to everything that is going on, you want to read this well thought out article. The Gait Guys are digesting this article and we will render our thoughts and opinions shortly. But, differing points of view, when laid out logically and with sound reason, deserve consideration. This is how the truth is eventually discovered.
Give this article a productive and attentive read. We will get back to you shortly.
Summary statement seems to be this….. (quoted word from word from the article).
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“Ironically, the popular press has been using the Harvard study as a launching pad for the idea that barefoot running is healthier than shod ambling, even though Lieberman’s paper provided no data at all to test the idea that barefoot running lowers the risk of running injuries!
Here’s what Lieberman et al actually found:
(A) Habitually shod runners (groups 1 and 5 from above) who grew up wearing shoes are usually rear-foot strikers (RFS), meaning that their heels make the first impacts with the ground during running, right at the beginning of the stance phase of gait. This is not new information. The strong link between running in shoes and heel-striking has been known for many years.
(B) Runners who grew up running barefooted or who switched to running barefooted (groups 2, 3, and 4) are generally fore-foot strikers (FFS), meaning that they tend to land initially on the balls of their feet while running, after which their heels drop down to make contact with the ground. Again, this is nothing new – the tight connection between barefoot running and FFS (and also MFS, mid-foot striking) has been general knowledge for years.
© Impact forces transmitted through the foot, ankle, and leg immediately after impact with the ground are about three times greater in shod runners using RFS, compared with barefoot runners with FFS. Some – but not all - previous studies have shown this same relationship, with RFS producing greater impact force during the first portion of stance, compared with MFS and FFS. The sudden rise in force with RFS, immediately after ground contact, is known as the “impact transient.” The disparity in impact transient between barefoot and shod running represents a “foundation” for the belief that barefoot running is “safer” and less injury producing. While this appears to be logical thinking, it is important to know that no study has ever shown that greater impact forces during the first portion of stance magnify the risk of running injury.
(D) Rates of loading of impact force are actually quite similar between shod RFS runners and barefoot FFS athletes (Figure 2b from the Nature paper). The rate at which impact force is loaded into the leg has also been suggested to be a risk factor for injury, although convincing proof of this notion does not exist.
(E) During the early stance phase of barefoot FFS running, there is greater knee flexion, greater dorsi-flexion at the ankle, and a 74-percent-greater drop in the center of mass, compared with shod RFS running. “Vertical compliance” is defined as the drop in the runner’s center of mass relative to the vertical force during the impact period of stance, and it is obviously greater in barefoot FFS running, compared with shod RFS. Vertical compliance varies as a function of running-surface hardness, and this is why force-loading rates are similar for barefoot FFS runners over a wide array of running surfaces (the runners adjust compliance according to surface). This is not novel information, however.
(F) During barefoot FFS ambling, the ground reaction force torques the foot around the ankle (and therefore increases the amount of work carried out by the ankle, compared with shod RFS running). With shod RFS running, the ankle converts little impact energy into rotational energy. Potentially, this could spike the rate of ankle-area injuries (for example in the Achilles tendon and calf) for barefoot runners, although this hypothesis has not been tested.
And that was pretty much it! The Nature investigation did disclose some interesting information about the effective mass of the foot and shank (which we won’t discuss here), but it offered no other information about the potential links between barefoot running and either injury or performance. And that’s why it’s too early for you to consider changing from shod to barefoot running, unless such a shift would be a lot of fun for you.
There’s just no proof that barefoot running will reduce your risk of injury or make you faster. In fact, it’s important to remember that most injuries in running are caused by an imbalance between the strain and micro-damage experienced by a muscle or connective tissue during training and the tissue’s ability to recover from such stress. This imbalance can occur when training is conducted shod – or barefooted! A weak or overly tight hamstring muscle which has been undone by excessive mileage won’t care if its owner was running barefooted or wearing shoes – it will still feel the pain. ” -
Owen Andersson, http://educatedrunner.com/Blog/tabid/633/articleType/ArticleView/articleId/797/BAREFOOT-RUNNING-WHAT-THE-HARVARD-STUDY-REALLY-SAID.aspx
