1. Barefoot running is different and no shoe perfectly replicates the barefoot condition. Running barefoot, particularly on a hard surface, increases the likelihood that a runner will adapt a midfoot or forefoot strike. Running barefoot will also generally result in an increased stride rate and decreased stride length.

2. Running in a shoe with no cushioning will simulate some aspects of barefoot running, but will not necessarily simulate the barefoot condition perfectly. This might in part be due to the ability of any type of sole, even one with no cushioning, to reduce friction between the foot and the ground and thus reduce plantar skin abrasion.

3. Running in a “minimal” shoe with a moderate amount of cushioning is unlikely to alter form very much, particularly foot strike. In other words, if cushioning is present, a heel striking runner is unlikely to move to a midfoot or forefoot strike.

A new study was just published on-line in the journal PLOS One that adds additional support to some of what I have written above (full text available here). Here’s the Abstract:

Comparison of Minimalist Footwear Strategies for Simulating Barefoot Running: A Randomized Crossover Study

Karsten Hollander, Andreas Argubi-Wollesen, Rüdiger Reer, Astrid Zech

Published: May 26, 2015, DOI: 10.1371/journal.pone.0125880

Abstract

Possible benefits of barefoot running have been widely discussed in recent years. Uncertainty exists about which footwear strategy adequately simulates barefoot running kinematics. The objective of this study was to investigate the effects of athletic footwear with different minimalist strategies on running kinematics. Thirty-five distance runners (22 males, 13 females, 27.9 ± 6.2 years, 179.2 ± 8.4 cm, 73.4 ± 12.1 kg, 24.9 ± 10.9 km.week^-1) performed a treadmill protocol at three running velocities (2.22, 2.78 and 3.33 m.s^-1) using four footwear conditions: barefoot, uncushioned minimalist shoes, cushioned minimalist shoes, and standard running shoes. 3D kinematic analysis was performed to determine ankle and knee angles at initial foot-ground contact, rate of rear-foot strikes, stride frequency and step length. Ankle angle at foot strike, step length and stride frequency were significantly influenced by footwear conditions (p<0.001) at all running velocities. Posthoc pairwise comparisons showed significant differences (p<0.001) between running barefoot and all shod situations as well as between the uncushioned minimalistic shoe and both cushioned shoe conditions. The rate of rear-foot strikes was lowest during barefoot running (58.6% at 3.33 m.s^-1), followed by running with uncushioned minimalist shoes (62.9%), cushioned minimalist (88.6%) and standard shoes (94.3%). Aside from showing the influence of shod conditions on running kinematics, this study helps to elucidate differences between footwear marked as minimalist shoes and their ability to mimic barefoot running adequately. These findings have implications on the use of footwear applied in future research debating the topic of barefoot or minimalist shoe running.

Methods

In a nutshell, the study authors recruited 35 runners and had them run trials at 3 speeds (12:04 min/mile, 9:38 min/mile, 8:03 min/mile if I did the math correctly) in each of four different footwear conditions. The footwear conditions (see image at top of post) were barefoot, shoe with no cushion (Leguano), shoe with moderate cushion (Nike Free 3.0), and standard running shoe (Asics 2160). They recorded the following biomechanical variables during each trial: ankle angle at footstrike, knee angle at footstrike, stride frequency, step length, frequency of rear-foot strikes.

Results

Barefoot running was significantly different from all other footwear conditions (including the shoe with zero cushion) for three of the five variables measured. When barefoot, runners exhibited reduced ankle dorsiflexion at contact (flatter foot strike), increased stride frequency, and reduced step length. Barefoot runners still exhibited a heel strike about 60% of the time, which was similar to the zero-cushion shoe condition. In cushioned shoes, heel striking was observed about 90% of the time.

When subjects ran in the shoe with zero cushion (Leguano) they exhibited reduced ankle dorsiflexion at contact, increased stride frequency, reduced step length, and lower frequency of heel striking relative to both cushioned shoe conditions.

The cushioned minimal shoe (Nike Free 3.0) differed from the standard shoe (Asics 2160) in that the runners exhibited increased stride rate and reduced step length. Ankle angle and frequency of heel striking did not differ between the two cushioned shoes.

Knee angle at foot strike did not differ between any of the footwear conditions (barefoot included).

Commentary

The results of this study suggest a gradation of effect of running footwear on form. None of the shoes mimicked the barefoot condition perfectly, even the minimal shoe with no cushion. When barefoot, the runners had the smallest amount of ankle dorsiflexion, a higher cadence, and a shorter stride. The zero cushion shoe yielded similar results to barefoot for foot strike, and had intermediate values for ankle angle. Stride rate decreased incrementally from the zero cushion shoe to the standard shoe, and step length increased incrementally from the zero cushion to the standard shoe.

This study by Bonacci et al. found a similar reduction in stride length and increase in stride rate in the Nike Free relative to a traditionally cushioned shoe, so it does appear that a moderately cushioned shoe may induce some amount of form change in the direction of barefoot running. That being said, retention of a heel striking gait in such shoes can lead to increases in impact forces over traditional footwear.  Although the importance of impact forces to injury risk remains a source of debate, it seems prudent to suggest that care should be taken when migrating toward shoes with moderate cushion.

One of the disadvantages of this study is that it looked at immediate change in runners who were not familiar with running in minimal footwear, so we can’t know for sure if changes from the standard shoe might become more apparent with time and additional adaptation to such shoes.

In my own research I have found that barefoot runners on asphalt are more likely to midfoot or forefoot strike compared to runners in the minimally cushioned Vibram Fivefingers. Combined with results from the study discussed here (and others), these findings support my belief that barefoot running is different from running in any kind of shoe, and that although a zero or minimally cushioned shoe can alter form in the direction of barefoot running, it may never perfectly simulate what happens when you take your shoes off. At the same time, running in a minimal shoe is different than running in a more traditional shoe, but it might take removal of most or all of the cushioning to elicit major changes in running form (at least in the short term).

I planted myself behind a bush about a quarter-mile from the starting line, and wound up getting slow-motion video (300 frames/sec) of 169 barefoot runners, and 42 runners wearing Vibram Fivefingers shoes (other footwear were represented as well, but sample sizes were small). My goal was to compare foot strike patterns between these two groups, as well as to compare patterns to those observed in other studies published on recreational runners wearing typical cushioned shoes.

I didn’t really do much with the video for a few years. I’d had some students analyze some of it for a senior research project, but the data needed some work if it was going to be publishable. Last Spring I met Martyn Shorten, head of the Runner’s World Shoe Lab, and we were chatting about our mutual interest in filming road races to look at form. When I told him about the NYC dataset he urged me to publish it, and put me in touch with Daniel Lieberman and Irene Davis. They were organizing a special edition of the Journal of Sport and Health Science on the topic of barefoot and minimalist running. They encouraged me to analyze and submit the data for publication – it was the push I needed, and I got it done.

The article I wrote was just published on-line – you can read the full text here. Here are the key points (note – midfoot strike means simultaneous contact of the heel and base of the fifth metatarsal):

1. For barefoot runners: 59.2% were forefoot strikers, 20.1% were midfoot strikers, and 20.7% were rearfoot strikers.

2. For minimally shod runners: 33.3% were forefoot strikers, 19.1% were midfoot strikers, and 47.6% were rearfoot strikers. Yes, almost 50% of the runners wearing Vibram Fivefingers contacted first on the heel.

3. The foot strike distributions were significantly different between the two groups.

4. Foot strike distributions for both groups differed from previously reported distributions in shod road runners (where ~90% of runners tend to heel strike).

What does all of this mean? Here’s my take on the significance of these results:

1. Barefoot runners are less likely to heel strike on asphalt than both minimally and traditionally shod runners. That being said, some barefoot runners (about 1 in 5) do continue to contact initially on the heel. This could be due to a lack of experience with barefoot running for some subjects observed. Anecdotally, my experience is that some people will immediately switch to a forefoot strike when you take their shoes off, others do not. Research suggests that for some people foot strike may change with experience. It could also be the case that a mild heel strike as typically exhibited by the barefoot runners is not a problem on a hard surface.

2. It is not easy to quantify and I did not attempt to do so in the paper, but the heel strikes observed in barefoot and minimally shod runners were typically not characterized by the extreme dorsiflexion you sometimes see in traditionally shod runners. For example, you don’t tend to see this type of pattern:

I’ve previously written about the fact that not all heel strikes are the same – we are beginning to realize that there is a lot of variation in how forces are applied even with the category we refer to as a “heel strike.”

3. The minimal shoe pattern differed from the barefoot pattern. Why? First, it’s possible that the Vibram runners were less experienced and thus opted to wear shoes rather than run barefoot in this “barefoot” race. Thus, they may not have had as much time to adapt their form. Second, the Vibram shoes may have provided enough cushion to make a heel strike on asphalt comfortable. Third, it may be that some factor other than a lack of cushioning is responsible for the reduced frequency of heel striking in barefoot runners. For example, a shoe sole also provides resistance to abrasion/friction with the ground. Removing that sole may require modifications of form to prevent damage to the plantar skin that are not required even when wearing a very minimal shoe.

What I’ve come to realize over the past several years is that determination of foot strike is multifactorial – I don’t think there is one right answer that applies to all conditions (and we now have evidence that some habitually barefoot humans heel strike a lot). The specific foot strike adopted by a given runner likely depends on some mix of footwear, running surface, running speed, running experience, etc. If you want to maximize the likelihood of observing a forefoot strike, I think you look at an experienced runner who is A) barefoot, B) has previous experience running barefoot, C) is running at a relatively fast pace, and D) is running on a hard surface like and asphalt road. That doesn’t mean that all runners under those conditions will forefoot strike, but I think the combo is most likely to encourage a form change from what we typically see in conventionally shod runners.

I elaborate on these points in a lot more detail in the actual paper, which you can read here. If you have any questions/thoughts, feel free to leave a comment.

I get the sense that most people equate the phrase natural running with barefoot running, or at least running with a form similar to that which you would adopt when barefoot (shorter stride, increased cadence, more plantarflexed foot at contact, generally a reduced impact transient if not heel striking, etc.). I largely agree with this definition. However, I think there’s a bit more to it than this.

Though barefoot running form has certain general elements that characterize it, it’s not something that can be defined concretely. There is no single barefoot running form, and thus there is no single natural running form that applies in all circumstances for all people.

Understanding what natural running means is further complicated by the fact that it’s become increasingly common for barefoot and natural running to be equated with forefoot striking alone, whether that is the intended message of those teaching natural running form or not. Sometimes a 180 cadence and forward lean are tied in, but I’m not going to go there in this post or I’ll never stop writing…

The reality is that running form is highly variable, and is largely dependent on an individual runner’s body and the conditions in which they are running (things like speed, surface, incline/decline, etc.). This applies even to foot strike. For barefoot runners, things will change depending on speed, surface, etc. There are habitual barefoot runners that forefoot strike, there are habitually barefoot people who heel strike when they run on softer surfaces. There are barefoot runners who heel strike on asphalt (and I have seen some very experienced barefoot runners making initial contact on the heel while running on asphalt). Most shod runners probably forefoot strike running uphill, and heel strike on the flats and downs.

In fact, when it comes to foot strike, Prof. Daniel Lieberman of Harvard emphasized variation when I interviewed him for my book. He said:

“I think everybody does everything. This idea that you’re just a forefoot striker, or just a midfoot striker, just a heel striker is bizarre. Variation is what biology is all about – everybody does everything! I think barefoot runners heel strike sometimes, of course they do. I don’t think they do it all the time. It’s speed dependent, terrain dependent, warm up dependent, etc.”

Let’s take a look at  a few videos from the 2011 NYC Barefoot run to further emphasize this point. When we think about natural running form, we tend to think of something that looks like this – short stride, forefoot strike, vertical shin at contact, etc.:

But, sometimes, barefoot running form on asphalt looks like the video below – is this natural running form?

How about this clip, which of these runners is exhibiting natural running form?

To a certain extent, I’d argue that all of the barefoot runners in the above videos are using natural running form. They are using the form that is working for them in their current situation, with zero assistance from footwear or other technology. That’s really how I would define natural running. It’s not some ideal, archetypal running form, it’s what happens when you let your own body figure out what works best for you when you minimize interference between the foot and the ground. It’s what happens when you let your own muscles, ligaments, tendons, and bones do all or most of the work. It will vary depending on the type of ground under your feet, how fast you’re running, and so forth. It could hurt you – just because it’s “natural” does not necessarily mean that it’s always good. It could also help you – some people have overcome chronic injury by going “natural.” It’s a form employed by you, not necessarily a form employed by all. And your natural running form can change with time and practice. It might reach a comfortable steady state, or it might continue to change in small ways.

The last point is an important one. The form employed by the barefoot runners in the videos above is their current “natural form” while running easy on asphalt, but it may not be the “best” form that they could be using given the situation. If they are inexperienced, their form may change over time as they continue to practice. There may be some residual baggage in the form of ingrained motor patterns from running “un-naturally” with the assistance of footwear for many years (and yes, for good or for bad, I absolutely believe that shoes, even minimal shoes, change the way we run). Practice may be a required element to finding one’s natural running form.

It’s worth considering, however, that given that the individuals in the above videos came to a barefoot running event (some traveled a long distance to attend), we might assume that they have at least some experience running barefoot. Furthermore, unless they jumped in after the race started, these videos are taken of people running a second loop around Governor’s Island (i.e., they had already run a few miles on asphalt). Maybe heel striking is “natural” for them.

Now that these videos are posted on-line, I fully expect the usual slew of YouTube comments telling the heel strikers that they’re idiots and they might die if they keep running that way. Will they break their calcaneus? Maybe, maybe not. Most are running with other hallmarks of barefoot running form – short stride, bent knee, etc., and we can’t tell what the forces acting upon them at contact look like from a video. If they are highly experienced barefoot runners without an injury history, I’d probably just tell them to keep doing what their doing. Embrace the heel strike! Their natural running form is working just fine. If they are inexperienced, some advice or coaching might help them along the way to undoing their neurological baggage and finding their natural form without getting hurt.

As a final point I’ll say that “unnatural” isn’t necessarily bad. I run the vast majority of my miles in cushioned shoes. I’m pretty sure my form would change a bit if I ran regularly barefoot. But, I haven’t been injured seriously in 6+ years of regular running, and I’ve never missed a target race due to a running related injury, so I’m not too concerned about my form. My wife has found that the only shoes she can run in without foot pain are Hokas. Sometimes a bit of help from a shoe can keep you going, and there’s no shame in that.

How about you, how would you define natural running?

The article is authored by Kevin Hatala of George Washingotn University and colleagues and is titled “Variation in Foot Strike Patterns during Running among Habitually Barefoot Populations.” It was published in the on-line, open source journal PLOS One (you can read the full text here).

The Hatala study certainly is thought provoking, and it raises a number of interesting questions regarding the factors that determine how our foot strikes the ground when we run.

Let’s start by looking at what they did.

Methods

The group filmed 38 individuals (19 male, 19 female) from a habitually barefoot tribe in Kenya (the Daasanach) as they ran along a packed sand surface onto a pressure mat. In his interview with Amby Burfoot, Hatala describes the surface as “…a firm sand surface. It has a little give, but it’s not at all like a beach sand.” The running trackway was about 15m long. It is not clear to me if any warmup running was conducted. The runners each ran along the trackway 3 times at a self-selected endurance running pace, and 3 times at a sprinting pace.

The group defined foot strike based on the location of pressure recorded by the mat at initial contact:

“A RFS was identified as a trial in which the first data frame included pressure on the heel only. A FFS was identified as a trial in which plantar pressure was exerted only on the forefoot (metatarsal heads) at touchdown. The heel almost always contacted the ground in these cases, but not until later in the stance phase. A MFS was considered to include trials where initial contact occurred at the lateral midfoot (cuboid/base of the 5th metatarsal), and also those trials where initial contact included both the heel and forefoot.”

I would quibble a bit with their definition of a forefoot strike since contact way up by the metatarsal heads is pretty rare in the videos I have analyzed over the years – I tend to view a forefoot strike as one that involves initial contact anywhere from the base of the fifth metatarsal forward without concurrent heel contact. A midfoot strike would only include those landings with simultaneous heel and forefoot contact. As such, I’d be wary of interpreting too much from the rarity of “forefoot strikes” in their results.

Results

At average endurance running pace (3.3 m/s, or a bit over an 8:00/mile pace, though the individual range was up to a 12:30 min/mile pace), 72 percent of the foot strikes observed were heel strikes, and 28 percent were midfoot/forefoot. They did not break this down by individual, so it’s hard to know if, say, the 28% who were midfoot/forefoot striking were doing so in all of their trials (this data would have been helpful). At the fastest sprint paces (6-7 m/s, or about 3:50-4:30 min/mile) they observed 40% heel strikes and 60% midfoot strikes (note that they observed no forefoot strikes at the fastest pace range, which I think has mainly to do with how they defined a forefoot strike as contact at the met heads). They found a significant speed effect – the subjects were more likely to switch to a midfoot/forefoot strike as speed increased.

Commentary

Most of the discussion surrounding this paper has been regarding how the results contrast starkly with those reported by Harvard’s Daniel Lieberman in his now famous 2010 study of barefoot Kalenjin runners from Kenyan. In that study, among other things, Lieberman observed that those Kenyan adolescents who had never worn shoes landed on their midfoot or forefoot 88% of the time when running at a self-selected pace on a dirt road (contrary to what was written in the New York Times article, Lieberman’s Kenyan subjects were not running over a pressure mat). This is obviously quite a different result from that reported by Hatal et al.!

The results have been interpreted to suggest that maybe we humans did not evolve to run barefoot using one particular type of foot strike. The reality is that Lieberman’s own data had already indicated the same thing – although the percentage was far lower, a few of his fast running, habitually barefoot Kalenjin subjects did indeed land on their heels (their self-selected pace was about a 4:50 min/mile). I was fascinated by this particular finding, and asked Lieberman if we should all be using only one type of footstrike when I interviewed him for my book. Here is the passage from Tread Lightly where I quote his response:

“So is there even a “one-footstrike-fits-all” scenario? Daniel Lieberman says no, expressing skepticism that there exists one optimal type of foot strike that should be used under all conditions. “I think everybody does everything. This idea that you’re just a forefoot striker, or just a midfoot striker, or just a heel striker is bizarre. Variation is what biology is all about—everybody does everything! I think barefoot runners heel strike sometimes, of course they do. I don’t think they do it all the time. It’s speed dependent, terrain dependent, warm up dependent, etc.”

I think this quote really gets to the heart of the issue. The reality is that foot strike is likely influenced by a whole bunch of different factors, and to their credit the authors of the paper discuss many of these. It’s also very difficult to compare the results of the Hatala study with the results of Lieberman’s study because they don’t represent a very controlled comparison. Perhaps the most important difference is the fact the Daasanach studied by Hatala are not known to be habitual runners – regarding this, Hatala stated the following in his interview with Burfoot:

“…I would say that there is not a clear “running culture” such as that which the Kalenjin are known for. Children are always running as they spend a great deal of time playing outdoors, but it is not common to encounter someone running purely for exercise.”

In contrast, Lieberman’s habitually barefoot subjects averaged nearly 20 km of running per day. In other words, one sample practiced the movement pattern being studied an awful lot every single day, whereas there other sample did not. We are now learning the importance of neuromuscular control in determining running form, and it’s not so surprising to me that a population that doesn’t run much at all might adopt a foot strike that is a bit different than that of a high mileage sample. What was particularly striking (no pun intended!) to me here were the results observed during sprinting – it’s odd to see such a high percentage of heel strikes in a sprinting gait, and this makes me wonder if there is something unusual about the Daasanach sample.

Other factors might also come into play here as well. It’s really difficult to know for sure, but there may have been differences in surface hardness between the two studies (packed sand plus pressure mat on top vs. dirt road), and both are likely quite different than the asphalt that many of us run on day in and day out (data I have for barefoot runners on asphalt is much closer to what Lieberman observed). Surface properties are well known to influence things like limb stiffness, and this should be considered in any discussion of foot strike (and Hatala et al. do emphasize this).

Problems not much discussed with the Hatala protocol is that there does not appear to have been a warmup, the runway was only 15m, and the runners had to land on a pressure plate (leading to the possibility of mat targeting). These factors are frequently cited as problems by biomechanists I have spoken to who do lab-based research, and is why many prefer using a force treadmill even though it also might not perfectly simulate overground running – they feel that the drawbacks of using a treadmill for analysis are far fewer than those associated with having subjects run along a short trackway. In other words, you can get away with running on your heels for 15m, but try doing that continuously for several miles and you might see a different response.

The last point I’ll make here is one that have made repeatedly – all heel strikes are not created equal. There is enormous variation in the category we refer to as “heel strike,” and this includes variable ankle dorsiflexion, variable position of the contact point relative to the center of mass, variation in joint angles, and so forth. It’s quite possible that another aspect of gait is more critical to our ability to run barefoot than foot strike – for example, gait expert Jay Dicharry believes that stride length may in fact be much more important, and it is well known that running stride length tends to shorten when people take their shoes off. My guess is that it would be unlikely to find the Daasanach runners overstriding barefoot to the degree that many recreational runners do. It is worth noting that the foot in the photo of a heel strike accompanying the article (see below) is actually still quite a way from making contact with the pressure mat – a lot happens to foot position and lower limb orientation in the final milliseconds prior to contact.

In summary, I found the results of this paper to be very interesting, but I think they need to be interpreted in the context of the subject population (mostly non-runners) and the conditions under which they were obtained. The great value of this study to me is that it highlights the fact that we don’t know everything there is to know about what determines foot strike patterns, and it emphasizes that we can’t simply say that everyone who grows up barefoot will forefoot strike when they run barefoot. It’s just not that simple. The human body is incredibly adaptable to the conditions it finds itself in, and as Lieberman pointed out, we need to investigate in more depth how factors like speed, surface, warmup state, running history etc. affect foot strike and other aspects of running form.

Like any good piece of science, this one raises a lot of questions, and based on the author’s comments in his interview with Amby Burfoot, it sounds like they are teaming up with Lieberman to investigate the factors that distinguish the samples they studied. It will be interesting to watch for their results!

Methods

The authors recruited 22 highly trained, high-level runners (mean 10K time of 33 minutes) and provided them each with a pair of Nike Free 3.0 and Nike Lunracer 2 running shoes. They were given 10 days to run a few times barefoot and in the new shoes so that each condition would not be entirely novel. They also ran in their usual running shoe (which was on average about 125-140g heavier than the two lightweight shoes).

The researchers filmed the runners with a 22-camera 3D Vicon system on an indoor track, and measured force using 8 force plates (this was a pretty high-caliber setup). The combination of cameras and plates allowed them to capture biomechanical data from a 20m long section of the track.

After a warmup, Each runner performed 10 running trials in each of the four conditions (barefoot, Free, Lunaracer, variable standard shoe). Average speed was 4.48m/s (about 6:00/mile) during the trials, so they were running far faster than most recreational runners.

Results

The results of the study basically showed that running barefoot is a lot different than running in shoes, but that the three shoe conditions didn’t differ all that much.

The only real difference between the shoes was that runners tended to have shorter, quicker strides in the Frees and Lunaracers vs. their standard shoe (mean cadence 183.9 steps/min for both lightweight shoes vs. 181.3 steps/min  in standard shoe). The Nike Free did reduce peak ankle adduction during stance and increased peak ankle internal rotation moment equivalent to barefoot, but in all other respects was more similar to the other shoes.

The real standout here in terms of biomechanical differences was barefoot running. Here are some of the key differences that were found for barefoot relative to the shoes:

1. shorter stride length than all shod conditions
2. higher cadence than all shod conditions (avg. 187.7 steps/min)
3. less dorsiflexion of the ankle at initial contact (i.e., flatter foot placement at contact)
4. greater ankle plantarflexion at toe-off
5. reduced knee extension and abduction moments
6. less knee flexion during midstance (straighter leg)
7. smaller joint moments and less work done at the knee (24% less negative work when barefoot compared to the standard shoe)
8. greater joint moments and more work done at the ankle

The authors summarize by saying: “Knee and ankle mechanics when running barefoot were different to all shod conditions, including the minimalist shoe, indicating that the minimalist shoe cannot entirely replicate the mechanics of running barefoot.”

Thoughts

This study provides further confirmation for a pattern that we are starting to see over and over. That is: barefoot running mechanics are different than shod running mechanics, particularly when comparing barefoot to a well cushioned shoe. Barefoot running tends to reduce work done by the knee and increase work done by the ankle. From a therapeutic standpoint, barefoot running may have benefits to those with knee issues, but may put the foot, ankle, Achilles, and calf at greater risk. Thus, knowing the individual runner and their needs/weaknesses is critical to avoid trading one set of injuries for another.

What I particularly liked about this study is that the authors were very open about admitting its limitations. For example, they point out the the Nike Free has quite a bit of cushion and an elevated heel. Habitual barefooters jump all over anyone who claims that the Nike Free replicates barefoot running, and this study seems to prove them right, at least in terms of how it affects biomechanics (and much to the chagrin of Nike marketing…). Studies of less cushioned shoes (e.g., Vibram Fivefingers) have revealed more similarity to barefoot running, but even ultraminimal shoes don’t seem to be a perfect mimic to running without footwear. They also admit that by not controlling the standard shoe they may have not as easily detected differences between the minimal and more traditional shoes.

Another important point that the authors emphasize is that their subjects were very highly trained runners and that as a result they might “already have highly consistent running mechanics and different types of shoes have little influence on their running gait.” They indicate that “It is possible that lesser trained runners with less consistent mechanics may be more susceptible to changes in running gait when utilising a minimalist shoe.” As always, one must consider the subjects and conditions studied when applying the results of a scientific study, and I’d once again love to take a look at individual variation.

The authors end the paper with the following conclusion, which I feel is a very nice summary of the implications of their study:

“In conclusion, the dynamics of running overground while barefoot are different to that of running in a minimalist shoe that has cushioning and an elevated heel. Athletes and their coaches should not expect to instantly replicate barefoot running while in a minimalist shoe. Running barefoot does induce mechanical changes to habitually shod highly trained runners gait and it is inherently different to shod running. The increase in work done at the ankle must be considered when transitioning to running barefoot as too rapid a transition may overload the triceps surae complex. Conversely, the reduction in joint moments and work done at the knee while running barefoot may provide potential benefits for the management of knee pain and injury.”

You can read the abstract to Bonacci et al., 2013 here: http://bjsm.bmj.com/content/early/2013/01/10/bjsports-2012-091837.full

English: Vibram FiveFingers Bikila shoes, top view. (Photo credit: Wikipedia)

The question of how footwear (or lack thereof) affects running economy has received a great deal of attention over the past year or so. Several studies have come out that have compared oxygen consumption in runners in both shod and unshod states, and most recently Franz et al. published a study showing that among habitual barefoot runners there is no significant difference in economy when “barefoot” (wearing only socks) vs. running in a lightweight racing flat (see my commentary on the Franz study here). The Franz study concluded that any economy gains due to weight savings when running in a simulated barefoot condition seem to be balanced by economy losses due to the lack of cushioning, which results in a non-significant difference between the “barefoot” and shod conditions.

However, until now, studies have not looked at how economy changes as a result of a period of barefoot or minimally shod training. A study, titled “Four-week habituation to simulated barefoot running improves running economy when compared with shod running,” was just published on-line in the Scandinavian Journal of Medicine & Science in Sports. In the study, authors J.P. Warne and G.D. Warrington of Dublin City University in Ireland investigate how 4 weeks of training in Vibram Fivefingers affects running economy and a variety of other physiological and biomechanical variables.

Methods

The study authors recruited 15 experienced collegiate runners who each ran a minimum of 6-7 days per week (minimum 50km per week of training). None of the runners were experienced or habitual barefoot runners. Each runner was given a pair of Vibram Fivefingers (VFF; weight = ~150g) and a neutral training shoe (weight = ~450g). During the pre-test, running economy was determined for each footwear condition by measuring oxygen consumption while running at both 11km/h and 13km/h on a treadmill. The researchers also measured heart rate, rated perceived exertion (RPE), stride rate, and foot strike type.

After the pre-test, the runners were assigned a 4-week transition program to acclimate them to running in the Vibram Fivefingers (the simulated barefoot condition). They maintained their typical weekly training volume in their typical shoes, but gradually added (or substituted) in mileage each week in the VFFs (two 15 minute runs the first week, up to 3-4×30 minute runs in week four). At the end of the four week period they ran a post test that was identical to the pre-test conducted at the outset.

Results

Pre-test results showed no difference in running economy between the training shoes and VFFs at either speed. Previous research has typically found that a 100g reduction in shoe weight leads to about a 1% increase in running economy. Given that the VFFs weighed ~250g less than the training shoes, it appears once again that any economy benefit of the reduced shoe weight seemed to be balanced by losses resulting from other properties of the barefoot-simulating footwear. These losses could be due to a lack of cushion, or in this study possibly a lack of familiarity with how to run efficiently in a barefoot-simulating shoe at the outset. The only difference that was found between the footwear conditions for the pre-test was that runners had a higher stride rate (and thus a shorter stride length) in the VFFs (83.69 strides/min in VFFs vs. 81.54 strides/min in training shoes).

What happened next was interesting. After the 4-week acclimation period, running economy in the Vibram Fivefingers increased dramatically (~8%), RPE decreased by 9.45%, and foot strike shifted more toward the forefoot. To a certain extent this is to be expected – as they acclimated to the novel footwear condition, the runners got more comfortable and more efficient at running in the barefoot-style shoes. However, more surprising is that in the post-test comparison the runners were now about 7% more economical in the VFFs than they were in the training shoes (the difference was statistically significant). They also tended to land more often on the forefoot in VFFs, and continued to run with a higher stride frequency in the VFFs compared to the training shoes. Economy in the training shoes improved by 2.32% after the 4-week period, but the improvement was not significant and the authors point out that this could simply be a normal training effect (i.e., 4 weeks of additional training would be expected to have some physiological benefit).

Commentary

So the big question here is why the runners were so much more economical in the Vibram Fivefingers when compared to the cushioned training shoes after using them for 4 weeks in training? The magnitude of the difference exceeds what would be expected from the weight difference alone (even when combined with any physiological benefit from 4 additional weeks of training), and the authors discuss some possible explanations. They speculate that the combination of increased stride frequency and landing more toward the forefoot may have resulted in a more effective recovery of elastic energy in the muscles and tendons of the feet and legs. They suggest that increased feedback from the ground surface when wearing a barefoot-simulating shoe might, through a period of motor learning, lead to “increased coordination and pre-activation of the dominant running muscles in anticipation of ground contact.” The resulting form changes (e.g., increased stride frequency, limb stiffness adaptation through changes in joint angles, and foot strike modification) could then explain the benefits to running economy in the barefoot-style shoes.

As I read this study I kept wondering to myself why they found such a large difference in economy between the VFF and training shoe conditions when Franz et al. found no significant difference in economy between “barefoot” (socks) running and running in a light racing flat (Nike Mayfly). There are a couple of differences between the two studies that are worth considering. First, Franz et al. recruited experienced barefoot runners and screened their subjects to only include those who landed midfoot/forefoot. They were specifically interested in the effects of shoe weight, so they tried very hard to control for form/biomechanics. In the Warne and Warrington study subjects were not experienced at barefoot running, and biomechanical differences were observed when they ran in the VFFs vs. training shoes both before and after the 4-week habituation. As such, form changes (e.g., shorter stride, foot strike change) resulting from a period of simulated barefoot training could explain at least part of the improvement in economy in the VFFs, and these may not have yet translated across to the training shoes (more time needed perhaps, or just not likely to happen in a 12oz training shoe?).

Another thing to consider is the type of footwear used for the “shod” condition in the two studies. Franz et al. used a light racing flat (Nike Mayfly), whereas Warne and Warrington used a heavy trainer (400g). It’s possible that some property of the shoes used influenced the results – for example, there may be a point of diminishing returns when it comes to shoe cushioning. As is pointed out in this article in the NY Times (discussing another study from Rodger Kram’s research group), there may be a cost to too much cushioning. As a personal aside, I find it very, very hard to run the same way in Vibram Fivefingers and a 12mm drop, 10oz+ training shoe, and I don’t know that form changes will ever perfectly translate from one to the other due to structural differences between the shoes (I don’t know if it’s wise to even try forefoot striking in a 12mm drop shoe).

One other related study is worth mentioning. In 2009, Squadrone and Gallozzi published results on habitual barefoot runners in which they found them to be about ~3% more economical in VFFs compared to traditional training shoes, which could be explained in part by a weight effect (though economy when barefoot was the same as in VFFs). However, even among these habitual barefooters there were biomechanical differences between the shoe conditions (e.g., joint angles at contact differed, foot strike was more posterior, contact time was higher, and peak impact force was higher in the traditional shoes vs. VFFs). All of this points to the complex effects that footwear can have on running gait. Shoe properties matter, experience of subjects matters, as do probably a variety of other factors.

Will this study end the debate about whether barefoot running is better or worse, or just different? No, not likely. But, it does provide some additional evidence that including some amount of barefoot or minimally shod running in your training routine can help you develop a more efficient running form (and things like barefoot strides have long been used as a training tool by high level runners for this very reason). However, it’s worth noting that benefits accrued from “barefoot” training may not translate directly to running in a traditional training shoe, particularly if your form reverts when running in that shoe. What needs to be done now is to figure out which factors specifically explain benefits gained as a result of barefoot/minimal training, and figure out how best to get those to translate to running in other shoes.  A longer term study might help accomplish this, and a study incorporating more explicit form training and cueing might help as well.

I always like to end posts like this with a call for anecdotal experiences – some hate anecdotes, but I find them interesting and informative. Have you sensed an improvement in your economy or perceived exertion after migrating to a more minimal or barefoot-style shoe? Share your thoughts in the comments!

The Running Event is the major annual trade show for the specialty running market, and is attended by brands showing off their newest product offerings, and retailers trying to figure out what’s going to be hot in the coming year. Based on the articles, the future of minimalism was a hot topic at the show, and I thought I’d add some of my own commentary on things that were written in the magazine.

Asics’ Simon Bartold on Minimalism and Running Injuries

The first article in the issue was an interview with Simon Bartold, an international research consultant for Asics. Simon and I have had our disagreements in the past, but I also think we tend to agree on many issues regarding the etiology and management of running injuries. His interview is interesting, and there are things I agree with, and things I don’t.

The first question asked of Bartold was “ HOW DO YOU THINK THE WHOLE BAREFOOT/MINIMALIST TREND IS EVOLVING?” His response:

“I actually think it’s dead. I think the big vibe around minimalism and barefoot as it existed 18 months ago has run its course.  We’re starting to see a lot of retailers say, ‘We really can’t sell it. Inventories are stacked up. And we can’t find anything to justify it scientifically.’ So it’s going to go back to where it was – what we called racing flats 10 years ago.

WHAT MINIMALIST PRODUCT ARE YOU TALKING ABOUT?  Mostly the zero-drop footwear and the whole talk of it as a main running shoe for the bulk of people. That’s the story we’ve been told. We’ve been told that if you go to a zero-drop running shoe then your gait will change and you’ll be running naturally like a caveman. But I think the concept has a fatal flaw and I believe people have seen through it. It’s taken 3 or 4 years but I think that concept is dead in the water.”

I both agree and disagree with what Simon says here. Sales at the barefoot-style end of the minimalist spectrum have indeed died down (particularly toe shoes like Vibram Fivefingers, though even those retain a very passionate niche following), and as with any hot trend things settle into place after an initial burst of popularity (and one must be careful not to equate minimalism with extreme barefoot-style and toe shoes). If he’s talking only about the idea that zero drop or barefoot-style is best for all people being dead, I agree with him, but I think only a small (albeit vocal) minority of people ever espoused that belief.

The reality is that minimalism and zero drop are far from dead – one need only look at the number of zero drop offerings coming out in early 2013 from top 7 brands like Mizuno (Be, Levitas, Cursoris), Brooks (PureDrift), and Saucony (Virrata) to see that zero drop is alive and well (not to mention that New Balance has a large suite of minimal offerings, Nike has the Free line, and adidas just released their own “adipure” natural running line a few months ago – of the big 7, seems that Asics is the only one not joining the minimal party, though they are testing the waters with the Gel-Lyte). Even small and niche companies are getting into the market with minimal spectrum offerings – Altra has developed a strong following and has a suite of new zero drop shoes coming in the next year, and Merrell continues to add zero drop models to their stable of offerings (would they be doing that if their sales had totally tanked?).

Minimalism is not dying, it’s evolving. We are learning through self experimentation – for example, I still like to run in a barefoot-style shoe from time to time, but I prefer a bit of cushion for most of my runs, many of which are in zero drop shoes. We are seeing the pendulum swing back a bit away from extreme minimalism, but more low and zero drop cushioned offerings are on the way. Minimalism may be dead for Asics, but then they never set foot in that market to begin with – it’s hard to evolve a product that you never made a go at.

Regarding Bartold’s comment about minimalism going back to the racing flats of 10 years ago, this is a tired argument that I hear too often and that I disagree with completely. Most so-called minimal shoes out there today are very different than racing flats. Flats tend to be stiff, tight fitting, and sacrifice durability for weight (and, ironically, they are almost never flat) – these are aspects that are specifically designed to support running fast, and Asics makes some very good flats based on what I have heard from other runners. In contrast, minimalist spectrum shoes come in a wide variety of weights (compare the almost 10oz Altra Instinct to the sub 5oz New Balance MT00), have variable amounts of cushioning (Saucony Kinvara vs. Inov-8 Bare-X 180), tend to be very flexible, and typically have a wide forefoot. Let’s please drop the “minimalist shoes are just re-marketed racing flats” line of argument.

I also disagree with Simon’s contention that we can’t find anything to justify minimalism scientifically, especially since he himself talks about different needs for different people (and I agree with him completely on this!). We have learned a lot in the past few years about how different footwear can alter forces applied to our bodies, how form training can be used clinically to treat injuries, and how footwear can influence our form. A barefoot-style shoe will alter force application just as a motion control shoe or custom orthotic will, it’s just a matter of understanding how forces are altered so that appropriate decisions can be made for each individual. None of these options are necessarily inherently bad, they’re just different, and one runner might benefit from a barefoot-style shoe whereas another might benefit from a more structured style of footwear.

I don’t want to come off sounding as if I disagree with everything that Bartold says, because I don’t. In fact I strongly agree with what he says here:

“The biggest problem with us as runners in the western world is we tend to run in the same manner, which means the same loading at each step, and the human body is very bad at adapting to that. This whole concept that you should mix the terrain you run on – some hills, some sand, some grass – and especially the look of the shoe to a less structured one at least a couple runs a week is completely logical from an injury prevention standpoint. Running in the same pair of shoes during the week is not varying the input signal enough. If you’re running on a different terrain or using a lightweight, lower drop, more flexible shoe like the GEL-Lyte for shorter, faster runs during the week, you’re not hitting the same repetitive load all the time. You’re not radically changing the experience, but enough to mix up the input signal in a positive manner.”

I’m an advocate for variation. Vary your shoes, vary your workouts, vary your terrain. Mix up force application and I think you will be better off from an injury prevention standpoint. This might mean a minimal shoe on some days, and a Hoka One One on others. There’s nothing wrong with using shoes that vary widely in their properties if it works for you, no need to be dogmatic about one style or another (and this is why I find it confusing that Bartold speaks so strongly against zero drop and barefoot-style shoes in one response and then openly supports variation in another).

I also agree with this:

“If you want to be active, there are risks involved and you probably will get an injury from time to time. And getting in better shape and doing simple exercises to strengthen your hamstrings and butt muscles will likely pay off better than changing your strike pattern. From a footwear standpoint, it’s very hard for us to build anything that we can say will definitely change injury rates because injury is caused by different things and footwear is a tiny piece of the jigsaw.”

I agree that too much emphasis has been placed on foot strike modification – yes, it can make a difference, but it can also cause problems, and one must be careful in making a change. There are also other things that can be done that might better protect you from injury than playing with your foot strike (strengthening, optimizing stride length, varying footwear and training, etc.). I might argue that footwear is more than a “tiny piece” of the jigsaw puzzle based on my own personal experience with a lot of shoes, but I’ll leave it at that.

Brand Views on Minimalism and the 2013 Shoe Market

The second article is titled “Running Market Retains its Mojo” and focuses more widely on trends in the running retail market. Once again I’ll focus mainly on the discussion of minimalism here, which the article introduces as follows:

“In the aisles the talk was still largely about the evolution of the minimalist trend. Marked by the slowdown with Vibram’s FiveFinger franchise, the market appears to be shifting for 2013 away from targeting purely minimal looks to offering a more generous amount of cushioning and structured options in a lightweight package. Heel-toe drops may fall in the zero to 8mm range, but stack heights (outsole to footbed) are coming closer to the 15 to 25mm range.

Nonetheless, lightweight still rules the day with motion-control shoes certainly not making a comeback. Many of the learnings of minimalism, including lean construction, flexibility as well as theories around natural motion and natural transition through the midfoot, continue to work their way into next year’s models.”

This passage really highlights to me the major positive outcome of the minimalist movement. It’s not so much that we now view ultraminimal shoes with no cushion as a viable option for some (but not all, and probably not even most) runners (don’t get me wrong, this is a good thing), it’s moreso that the trend has pushed the market in a new direction away from the old neutral-stability-motion control paradigm where almost every shoe was 10-12mm drop, looked pretty much the same, and weighed over 10oz.

We are now in a market filled with much more variety, and this is a great thing, but with variety comes complexity in choosing the right shoe, and this is where knowledgeable retailers are critical – science may or may not ever be able to tell us which shoe is ideal for you, and help from a retailer experienced with a variety of shoes is critical.

The article goes on to interview reps from various brands who share their thoughts on minimalism. Here’s a selection:

Ryan reports that Scott Tucker of Pearl Izumi feels barefoot and “super-low-to-the-ground, no-midsole” options are “dying away.” Ryan quotes Tucker:

“What we have been calling minimalism is evolving into something else which doesn’t have a name but which brands like Pearl Izumi are addressing,” said Tucker. ”It’s taking those elements that became popular in minimalism evolving them and making sense of it.”

In other words, we don’t know what to call it, but Pearl Izumi are on it! (I might offer that the term “transitional” shoe has been in use for awhile for this niche) Not exactly a winning marketing message, and I’m not sure what elements they are planning to make sense of since the major tenets of minimalism are pretty straightforward (less drop, less cushion, wider forefoot, greater flexibility, more work done by the runner’s body, etc.).

Next we have Dave Jewell of Zoot, who Ryan reports as believing the following with regard to form:

…although the running industry was due for a “reset” since shoes were becoming over-built over the years, he laments that much of the natural discussion is around the midfoot strike.

“I have an active son so I live and breath cross country,” said Jewell. “I go to practices and the coaches talk about running form – staying relaxed, running proud and not slumping your shoulders. These coaches who have been doing this well before these new shoes arrived never talked about midfoot strike. Running has nothing to do with where your foot lands.”

Running has nothing to do with where your foot lands? Nothing???

Now, I’ll grant that foot strike modification has been overemphasized, but there is plenty of science describing how foot strike can alter force application (Bartold even discusses it in his interview) and foot strike modification can be used as a therapeutic tool for some injuries. Just because his son’s cross country coach doesn’t talk about midfoot strike doesn’t mean that foot strike is not important. In fact, the cross country coach at my college (and he’s been coaching a long, long time as well) just sent one of his runners to me a few weeks ago to talk about his foot strike since he has been chronically injured (tibial stress fractures). Heck, prominent runners have talked about foot strike for over 100 years – Arthur Newton, Bill Bowerman, Joe Henderson, Tom Osler, Jim Fixx, Gordon Pirie, Ryan Hall and many others have all had some strong feelings on the topic (and they don’t all agree). As you might guess, I’m not a fan of black and white thinking along the lines of “Running has nothing to do with where you foot lands.” It can matter quite a lot for some people (such as the runners with anterior compartment syndrome in this study).

Let’s move along to what I thought were the best two responses from shoe manufacturers in the article. First is adidas:

“It’s an exciting time,” said Pete Stolpe, marketing specialist, running, Adidas America. “Because never in the history of the industry has there been more companies with more footwear. The individual runner can truly have a choice and a voice of what they want to put on their foot. If you’re a high arched runner, if you’re a forefoot runner, whatever your running gait is, whatever your distance preference is, there’s never been a time in the industry‘s history where you have more companies where each runner can absolutely choose what they want on their foot. The bottom line benefit is runners win because they have more choices than ever before and they have more of a voice. That’s fantastic for the health of the sport and makes it more inclusive as it’s ever been because there’s something for everybody.”

And then Brooks, who demonstrate here why they are now the leading brand in specialty running – this is as fine a statement of how things should be done as I have seen from any brand thus far:

Brooks Footwear Product Line Manager Carson Caprara said the research will seek
to “clear up” much of the ongoing conflicting information in the marketplace but particularly focus on the individual. For instance, the research will seek to explain why someone with chronic running injuries in the past may have suddenly become injury-free when switching to a minimal shoe. Perhaps even more puzzlingly, it will try to understand why someone else when viewed on a treadmill with the exact same gait alignment gets injured when wearing a minimal shoe.

“I think it may entail shifting the paradigm a little bit in how we look at runners and injuries and how we build shoes and that hopefully long term will resonate and make sense for retailers and runners across the spectrum,” said Caprara. “It will have an element of choice, but also bring a little bit of the science back into the equation about optimal running for each individual. And it’s going to focus less on there being one standardized baseline that everyone has to be aligned in this one way to what is your best alignment as an individual and looking at your optimal motion and your optimal alignment and figuring out how to keep you in that alignment as you run. And that’s very different because now it’s, ‘Let’s put a bunch of people on a treadmill and try to align them on the same plane.’ But for some people, that plane may not work.”

“It’s just a matter of not having one point of view but offering choices for runners and I really think that’s resonating,” said Caprara. “We’re not telling runners you have to run minimal or run core. Run them both. We’re going to build them both for your type of foot and you can make the choice on what you prefer.”

The future is not about minimalism, it’s about choice. With the variety that now exists in the running shoe market we can each individually hone in on our needs and preferences. Some of us will wind up being be minimalists, some of us will be maximalists, and neither is necessarily right or wrong. I mostly write about minimalism here on Runblogger because it’s my personal preference and I review shoes that I like to run in. That being said, I have no problem recommending a more traditional style shoe when asked if it’s appropriate and fits within the preferences of a runner looking for advice. Whether we land on our forefot, midfoot, or heel, we can likely find a shoe that will work pretty well with our chosen or unconscious (for those who could care less about form work) running style. We can also find a shoe that will accommodate the varying widths of our feet and meet our aesthetic requirements. We live in an exciting time as runners when it comes to our footwear options, and the shake-up that minimalism caused is a big part of that.

The challenge going forward is not so much adding more variety to the market (don’t get me wrong, innovation should continue), but rather to figure out how best to match a runner to a shoe among the variety that exists. As the Brooks rep points out, the methods we have been using (trying to control pronation so that we all look the same) have not stood up to scientific testing over the past few years. We need to move on, and we need scientists and retailers to work together to develop new and better protocols – neither in isolation will be able to answer this question in a general way for most people. Scientists need to continue to investigate better practices for matching runners to shoes, and retailers need to help scientists understand the footwear business and what methods will be most successful in a retail setting (e.g., it can’t require a million dollar piece of machinery or a Ph.D. in biomechanics to implement it).

The shoe industry has changed, of that there is no doubt. I ran my first mile in a pair of the original Nike Free 3.0’s back in 2009, and now the Nike Free is the best selling running shoe on the market (even if most who wear it don’t run in it). Times change, as do preferences, but I’m confident that we are moving forward in a positive way, and that the events of the past few years have changed the shoe industry for the better. I’m excited to see what the future will bring!

I highly recommend that you read the articles in SGB Weekly yourself: http://sportsonesourcecloud.com/sgbweekly/SGBW_1251hi.pdf

As always, thoughts are always welcome, leave a comment below!

“I’ve been trying to fight this trend for years now, but the masses have spoken.  In a battle that would rival BetaMax v. VHS, the term “barefoot shoes” has won out over “minimalist shoes.”  I concede.

Yeah, I know “barefoot shoes” is an oxymoron.  Yes, I know not all “barefoot shoes” give an experience that is remotely like being barefoot.  Yes, I know many of my purist friends will scoff my tossing of the towel.

The only people that use the term “minimalist shoes” are my ten barefoot friends.  The rest of the world calls them “barefoot shoes.”

I’ve long resisted the temptation to ever refer to a stripped-down minimalist shoe like a Vibram or a Merrell Trail Glove as a “barefoot shoe.” I’ve caved to the point of calling them barefoot-style shoes, but never straight-up barefoot (at least I hope I haven’t).

Quite frankly, I don’t even like to use the word “minimalist” to describe a specific category of footwear since there is so much variation within it. As I’ve written before, I view minimalist more as a relative term to describe shoes along a spectrum from the Brooks Beast to the bare foot (i.e., one shoe can be more or less minimal than another).

The reality is that Jason is right. The average person is far more likely to know what a “barefoot shoe” is than a “minimalist shoe.” Only serious runners and shoe geeks (and their poor spouses, children, friends, neighbors, etc.) are familiar with the minimalist terminology. Ask a random non-runner what a barefoot shoe is and the likely response will be “aren’t they those ugly things with the toes?” Ask the same person what a minimalist shoe is and you might get a blank stare.

If you don’t believe me, let me provide some evidence. I popped over to the Google Adwords Keyword tool last night for a bit of research. If you’re not familiar with the tool (and if you are a blogger, you should be!), it allows you to see how often particular term combinations are searched for via Google in a given month. Thus, it helps to determine what people call things when they are looking for information on-line. I plugged in the following three phrases: “running shoes,” “barefoot shoes,” and “minimalist shoes.” Here are the number of global monthly searches for each:

running shoes: 1,830,000

barefoot shoes: 135,000

minimalist shoes: 49,500

Barefoot shoe searches nearly triple minimalist shoe searches. What’s more, the phrase “barefoot running” beats out “minimalist running” 110,000 to 33,100.

What’s the big deal? The problem as I see it is that barefoot running and minimalist running are two truly different things. Not only is “barefoot shoe” and oxymoron, putting on a “barefoot shoe” creates an expectation that one will run as if they were barefoot. Sometimes this will be the case, but quite often it’s not, and this can create problems and increase injury risk.

For example, I was at the track last week and a guy and his wife/girlfriend showed up in his and hers Fivefingers (it was very sweet!). They had a metronome and were obviously working on “barefoot” form. However, he was heel-striking away as if he was wearing a traditional shoe. (Ironically, I was there attempting to get a high-school runner with injury problems who barely pronates when barefoot out of a pair of motion control shoes that had been “prescribed” to her by a local shoe store.) I have plenty of video of people continuing to run with a heel-striking gait in “barefoot shoes,” even on asphalt. Their form may change in other ways, but heel striking when barefoot causes a dramatic increase in the impact loading rate applied to the body, and a person heel striking in a minimally cushioned shoe like a Vibram is probably experiencing much more impact than someone in a regular running shoe – I suppose this defeats the purpose of making the switch.

I will concede that “barefoot shoes” as a category description is not going away. Although Vibram sales are declining, they will likely always fill a niche, just as other ulraminimal shoes do. But, I do think it is important to maintain a distinction: barefoot is barefoot, shoes are shoes, and the moment you put one on the other things change. Though I agree with the sentiment of Jason’s post, I just can’t bring myself to refer to a shoe as a barefoot shoe. I’ll continue to say “barefoot-style,” or perhaps “ultraminimal,” but that’s as far as I can go.

And now that I’ve addressed this most pressing of controversies, time to go for a run in my sort-of-barefoot-end-of-the-minimal-spectrum-trail-shoes :)

The goal of the study was to determine how heel striking vs. forefoot striking while running might alter: 1) lower back movement, 2) peak leg acceleration, 3) impact shock attenuation (i.e., how much shock is attenuated from the shin to the head), and 4) subjective comfort.

Methods

To address these questions, the researchers had 43 runners (24 male, 19 female) run barefoot on a treadmill using both a heel striking and a forefoot striking gait. Since 84% of the runners were heel strikers, in the vast majority of cases forefoot striking was a novel gait with which the runners had little or no experience. Shock was measured using accelerometers attached to the tibia and head, and lower back movement was measured using an electrogoniometer.

Results

Results of this study showed that running with a forefoot strike:
1) decreased total range of motion in the lower back, but did not alter peak   flexion or extension
2) reduced peak tibial acceleration
3) reduced shock attentuation from the shin to head (since there was less shock to attenuate)
4) reduced subject running comfort

Commentary

One of my critiques of this paper is the manner in which they cued a forefoot strike. Here’s what they told runners to do: “1) ‘try to run on your toes’ and 2) ‘do not let your heels touch the ground.’”

This is not the typical way barefoot runners run (the heel almost always comes down after forefoot contact – see the video below from the NYC Barefoot Run), and is the same cueing applied in a previous study, which I wrote about in an article for Lower Extremity Review:

“…Laughton et al. found no significant difference in loading rates between rearfoot and forefoot strikers and increased tibial acceleration in forefoot-striking runners. However, they looked at natural rearfoot strikers asked to switch to a forefoot strike pattern rather than natural forefoot-striking runners, and, furthermore, they instructed runners to run with a “toe-strike” and not let the heel touch the ground. In my observation, natural toe running without heel contact is extremely rare among runners, and the authors point out that running with this style of gait could have caused artificial stiffening of the leg, leading to an increase in tibial shock.”

Interestingly, even though they advised runners to run in a similar manner, Delgado et al. actually found that tibial acceleration was lower in forefoot strikers in this case. This is the opposite of what Laughton et al. found, and I’d be curious to see the results if the heel were allowed to come since that would allow increased use of the ankle and calf musculature in shock absorption and could further reduce the need for movement at places like the knee, hip, and lower back.

Regarding the finding that adopting a FFS reduced overall back movement, they report the following:

“Greater overall low back excursion with a RFS pattern may suggest that this pattern creates a greater demand for stability in the lumbar spine. Therefore, this foot strike could possibly not be beneficial for individuals with stability problems, including hypermobility or atrophied lumbar spine musculature. However, the change in ROM did not exceed known error of the measuring device for lumbar ROM, suggesting that the effect may not be clinically significant even though it reached statistical significance.”

Thus, the results thus could indicate a positive effect of switching to a forefoot strike for those with lower back pain, but the difference was not of such a magnitude that they felt comfortable stating this with certainty (anybody experienced a reduction in lower back pain as a result of changing footstrike? – let us know in the comments). Again, it would be interesting to see if things might change with slightly different cueing and greater experience with a forefoot strike – it’s always difficult to know with instantaneous changes with a novel movement pattern will change with time. Following on the the latter point, the authors propose that the reason for the perception that heel striking while barefoot was more comfortable despite causing greater shock was because the forefoot strike was novel for most of the subjects (I can’t help but wonder if the advice “to run on your toes” was also detrimental to comfort – this style of forefoot striking puts a lot more strain on the calf muscles).

Finally, regarding impact shock they say the following:

“This study revealed that there was lesser peak leg impact at contact when running with a FFS pattern. This is consistent with current evidence suggesting that running with a FFS would decrease shock when compared to running RFS (6,29,31). Shock attenuation was also observed to be greater with RFS than FFS; there is more shock absorbed throughout the body when running RFS. This may be due to the overall greater foot-ground impact to be generated in RFS, thus increasing the magnitude of shock to be attenuated.”

So, like many other studies, this one shows that running barefoot with a forefoot strike reduces shock to the body relative to running barefoot with a heel strike. Not much surprise there, but another piece of evidence suggesting that if you plan to run barefoot, it may be best to avoid those heels!

The study, titled “Relationships Among Self-reported Shoe Type, Footstrike Pattern, and Injury Incidence,” was authored by LTC Donald Goss of the US Army/Baylor University Doctoral Program in Physical Therapy and Dr. Michael Gross of the University of North Carolina. It will be published in the Oct/Dec issue of the Army Medical Department Journal.

Methods

The study authors crafted an internet survey and obtained responses from 2157 individual runners from Sept. 2010 to Dec. 2011. Of these, 1363 reported changing either their shoe type preference (traditional or minimalist) or foot strike in the previous year. Thus, the respondent pool was spit into two samples – 904 runners who completed the entire survey (not all did) and had not changed either shoe type or foot strike type in the previous year, and the 1363 who had made a switch in the previous year.

The specific survey question pertaining to injuries was the following:

“If an injury is defined as something that caused you to modify your training schedule for at least 1 week due to pain or discomfort (with or without formal medical care), have you experienced any lower extremity injuries in the past 12 months that you believe were caused by running?”

They followed this by asking respondents to specify the anatomical location of the injury (e.g., foot, ankle, knee, hip, etc.)

Results

Among the 904 respondents who had not switched shoe type or foot strike, 73% wore traditional running shoes, 25% wore minimal shoes (mean duration of minimalist shoe wear = 26 months), and the small remainder were primarily barefoot runners (only 16 total). Runners in the various groups were similar in mean height, age, and body mass, though minimalists were more likely to be male, had more years of running experience, and tended to report greater weekly mileage and faster training paces.

In terms of foot strike, 31% of the entire sample claimed to be heel strikers, 43% claimed to be midfoot strikers, 20% claimed to be forefoot strikers, and 6% were uncertain of their foot strike type. Barefoot and minimalist runners were more likely to self-report a midfoot or forefoot strike. The breakdown of self reported foot strike types among footwear groups looks like this:

Regarding injuries, runners in traditional shoes were 3.41 times more likely to report an injury than experienced minimalist runners (46.7% vs. 13.7%). As seen in the figure below from the Army Medical Department Journal, injury percentages were higher among traditionally shod runners at every anatomical location surveyed.

Comparing injury rates among foot strike groups, rearfoot strikers reported an injury incidence of 52.4%. In contrast, 34.7% of midfoot strikers reported an injury, and 22.8% of forefoot strikers reported an injury.

As mentioned above, a large proportion of the initial survey sample was excluded from the above analyses because they had either switched foot strike (n = 866) or shoe type (848) in the previous year. The vast majority of these people claimed to have moved from heel striking in traditional shoes to midfoot or forefoot striking in minimal shoes. The main reason reported for switching was a desire to overcome an injury (40-50%). The group of 397 runners who reported changing footstrike due to injury collectively reported 500 injuries, and the 372 runners who reported changing footwear due to injury collectively reported 411 injuries. It’s not specified if these injuries include those both before and after the change, so it’s difficult to conclude whether they might all be termed “transition injuries.”

Commentary

This is an interesting study for a number of reasons, but I want to state clearly at the outset that it is based on self-reported survey responses, and as such should not be confused with a prospective experimental study. In other words, we must rely on the accuracy and honesty of the survey respondents, which opens up a lot of room for debate on the value of the findings.

Regarding this, I’ll say that I am very skeptical of the self-reported foot strike percentages. To their credit, the authors openly state this as well, and have themselves conducted a pilot study showing that only about 75% of runners accurately self-report their foot strike type, and that those claiming to be midfoot or forefoot strikers are more likely to be incorrect (i.e., at least one-third who claim to land on the midfoot or forefoot are actually heel strikers).

My own research has shown that in a large sample of traditionally shod marathon runners, approximately 90% are heel strikers. A similar percentage of heel strikers was found again in a recent analysis of foot strike patterns at the Milwaukee Lakefront marathon. Thus, the self reported heel striking frequency of 41.4% for traditionally shod runners is probably a dramatic underestimate. I also have reason to suspect that the 5.9% frequency of heel striking reported by minimalist runners is also a vast underestimate (I need to publish my data on this!). Given this, my feeling is that the high likelihood of significant self-reporting error makes the comparison of injury rates by foot strike of questionable value. The authors are very clear in pointing this out themselves, and indicate that confirmation of foot strike types would make for a more compelling analysis.

In contrast to foot strike type, one would hope that experienced runners responding to a survey like this would know what kind of shoe they put on their feet. The authors did a pilot on this as well and found that 98% of runners could correctly classify their shoe as “traditional” or “minimalist,” though the detailed criteria that they used to differentiate these categories are not provided. Given the likely higher accuracy of shoe type classification, the finding that traditionally shod runners reported 3.41 times as many injuries as experienced (> 1 year) minimalist runners is interesting. One would hope that the respondents accurately reported their injuries, and most runners should be able to recall injuries that caused them to alter their training for more than a week, but it is possible that this result is tainted by enthusiastic minimalists underreporting their injuries (the authors point this out as well). This is the reason why prospective and carefully controlled and monitored studies provide more reliable results than surveys – it minimizes bias.

If we assume that the self-reports are accurate, then this study suggests that those adapted to minimalist shoes are on average at a reduced risk of injury compared to traditionally shod runners. Lots of questions, but that’s the major conclusion. However, if you consider the fact that those who transitioned their footwear or foot strike within a year of completing the survey reported an awful lot of injuries (keeping in mind that it’s not clear whether these occurred before or after the transition), the results don’t necessarily mean that minimalist is better for all. It just means that those who make it through the transition period tend to do pretty well. It could also be a reflection of some other factor – perhaps experienced minimalists get to that point because they have inherently better form or are more injury resistant and would do fine in any kind of shoe. All we can do is speculate based on the survey reports.

Transition of any type changes stress to the body, so it’s not surprising to me that injuries are more common in this period (though another study suggested that barefoot running transition injuries are actually uncommon). The big question to me is what happens to those people who get injured in transition? It would be interesting to do a follow up and see how many of those injured during transition stuck with it, and what their longer term outcomes were like. In other words, is going minimalist and/or moving to a forefoot strike a short term risk for a long term gain? I’d also love to see a before/after analysis of form and foot strike type. Though this study raises provides some interesting results, as with any scientific paper it also raises a lot of questions. My hope is that answers to these questions will continue to appear in the coming years.

What do you think, do you believe the results of this study?

If you’re interested, head over to the post on the Tread Lightly blog here: Are Barefoot Running Transition Injuries Actually Uncommon?

I have a fairly long history with the Vibram Fivefingers. I started running in KSO’s back in summer 2009, and they were my first truly “barefoot-style” shoe. I loved running in them, and they were the first shoe I had worn that really let me feel what a forefoot strike feels like. I’ve since tried the Bikila, TrekSport, Komodo Sport, and Komodo LS. Of these, I’ve put the most miles on the Bikila, but honestly have not run very much in Vibrams of late.

My reason for moving away from the Vibrams is that I find that when I run in the newer models that fit tighter and have more substantial soles, my right forefoot starts to ache under the region of the second metatarsal head after a few miles. By the end of a run all I want to do is rip the shoes off and wiggle my toes. I have heard similar reports from a number of people, and this post was actually prompted by the following report on a forum that I participate in:

“Thought I’d share this out, as I think I may have finally sussed out
the reasons why my forefeet have been hurting so badly on my lunchtime
runs.  My forefeet, just behind my second toes, have started hurting
like hell – like somebody had beaten on them with a ballpeen hammer –
when I run in my VFF’s.”

This describes quite well my experience, though my issue is more an ache than a sharp pain. This morning I decided to try an experiment – I walked my kids to school in VFF Komodos. My right forefoot was aching after we got to the school, so I took the shoes off and walked home barefoot. Ache went away almost immediately.

Why does this happen? My theory, at least for my own situation, is that the Vibrams actually restrict flexion and extension of my toes to quite a considerable degree (and also toe curling). I find it very hard to bend them up or down while wearing most of the VFFs I have, whereas in a shoe with an open toebox they are free to wiggle and curl as needed.

Why is this important? I think it’s because the toes initially need to flex upward just prior to ground contact (watch this video to observe this happening in barefoot runner), and then they need to flex downward to push onto and grip the ground (or sole) during stance, which takes some of the load off the metatarsal heads. Limiting flexion and extension of the toes messes up both of these processes.

So what is it about the toe pockets that does this, aren’t they supposed to allow greater toe freedom? Yes and no. I like that the toe pockets spread my toes out, but I find that my four little toes like to work as a unit, and it’s very hard for them to flex and extend the individual toe pockets, particularly when there is rubber connecting the forefoot to the toes. This is exacerbated by fit – I have a size 42 in KSO’s, which is a bit too long and there is quite a bit of space in front of my toes which causes the tips to catch the ground from time to time, and I have size 41s in the other shoes – in the others my toes fit snugly and reach but don’t push against the tips of the pockets, but by fitting snugly the material on top of the toe pocket gets tight and makes it very hard to flex the toe down. Of the VFFs I own, my KSO’s allow for the most flex, which is a combo of the fact that the toes are a bit long and the upper material is very stretchy (though the rubber connecting the toes to forefoot still limits my toe flexion to a degree).

As a result of this, I’ve grown very hesitant to recommend Vibrams to people wanting to try a barefoot-style shoe for the first time. Metatarsal stress fractures are one of the big concerns when it comes to transitioning to a very minimal shoe, and I worry that shifting load to the metatarsal heads might contribute to this, and that this could be further exacerbated in people with a long second metatarsal (Morton’s foot). Getting the right fit is critical, and this can be tough with the Vibrams, especially if you fall between sizes as I think I do.

Although I have concerns, I should also point out that I know plenty of people who love their Vibrams for running and who have no issues with them. So I do think they can be a great match if you combine the right pair in the right size with the right person. But, it’s hard for me when making a recommendation to know who will have success and who will have trouble, so I tend to avoid recommending them these days for running. There are lots of other options out now that give a similar type of ground feel and that don’t have the toe pockets, and some of these shoes are excellent (check out my minimalist shoe guide for some examples) – these options were not available even just a few years ago when the Vibrams got popular.

If I had to give advice to Vibram, I would say the following. Sales of the Fivefingers are slowing considerably, and part of this is that the toe-shoe fad is dying down. But, there will be a core of people who will still use them, and I see people in them in my home town quite often. Part of the problem I think is that Vibram responded to the popularity of the Fivefingers by pumping out a ton of new models, some of which were downright ridiculous (fashion boots???). I’d suggest focusing on a smaller number of models and making sure to get them as dialed in as possible for the purpose they will be used. If it’s a shoe meant for running, make sure the toes can properly flex and extend. Perhaps find a way of disarticulating the sole under the toes from the sole under the forefoot. Make the fabric on top of the toe pockets much stretchier, as it is in the KSOs. The new Vibram Seeya looks promising, and I’m hoping to give them a try to see if they improve on this (can anyone who had tried the Seeya share some thoughts?).

The bigger issue, and perhaps my biggest piece of advice, would be to make half-sizes. Proper fit is critical in these shoes as having toe pockets that are too short or too long can both cause problems. I’m pretty sure a size 41.5 would solve most of my issues with these shoes. You might even consider making a Vibram Morton for those with a long second toe :) I have no idea how costly it would be to increase size availability, but if it came at the expense of cutting some of the superfluous models, I’d see it as a very positive thing for the line. Trim the fat, and focus on making the core as good as it can be.

Anyone else have thoughts on the Fivefingers? Have you experienced toe flexion problems or forefoot ache in these shoes? Any suggestions for how to improve the line? Leave a comment!