A Skeptical Look at Masai Barefoot Technology Shoes
I was at the drug store the other day waiting on a prescription, when I noticed people trying on some funny shapped shoes that had curved soles. So, I walked over to the display and took a closer look. They were called MBT shoes, which stands for Masai Barefoot Technology, and are made by the company, Swiss Masai. They had hand-out brochures, so I took one to read while I was waiting. (Note that I will refer to the company as both MBT and Swiss Masai in this essay, as it appears that the company does the same on their website.)
For some of the research for this entry, I used MBT's website. It's an annoying, flash laden site that doesn't let you just sit and read about the technology, without having some java script decide you've spent enough time on that section and then brings up something else. Also, I couldn't find some of the statements on the website that first caught my eye on that brochure - so if you go to visit the site looking for them, you may not find them, either.
Anyway, there are a couple issues I want to discuss in this entry - briefly, whether or not these shoes have anything to do with "barefoot technology," and then in more depth, whether or not these shoes might actually have some therepeutic value.
I realize now as I'm getting ready to post this entry, that it's grown longer than I'd originally anticipated, so I'll get right to the point up front, before addressing the details. MBT shoes do show promise for treating certain conditions. However, there is anecdotal evidence that they can cause significant negative side effects. Additionally, there are not enough clinical studies addressing their efficacy or possible side effects.
I suppose I'll start out by quoting a bit from that brochure, to give an idea of what these shoes are and what the company is claiming they can do. Here's an excerpt from the page of that brochure that describes the inspiration to develop this shoe:
MBTs have been available on the market since 1996. But practical proof of the effectiveness of this technology has been provided for thousands of years by the Masai, a semi-nomadic tribe from East Africa well-known for their excellent posture. joint and back pain are mostly unknown among them, they enjoy stable health and remarkable athletic ability.
It was left to Swiss engineer Karl Müller to discover the secret of the Masai: the simple fact that walking barefoot on soft, natural ground means that they have to balance their bodies with each and every step.
Yes, the bold was in the brochure, as are all the other bolded sections in anything else I'll quote from them. Here's another excerpt from the brochure, from the page, "What Make MBT Different?"
Conventional shoes support and lead the foot, stabilizing the body in an unnatural way> This means that these imoprtant muscles lose their function. Like any other inactive muscel, they atrophy, which leads to many of the health problems of modern civilization, for instance joint and back pain.
It is relatively easy to counteract his effect: the body must be stimulated to balance itself. This is eactly what physiological footwear does, by inducing a natural instability in the body - which must constantly be compensated by the body's supporting muscle system.
And one more excerpt from the brochure, from the page, "How Does MBT Act on my Body?"
wearing MBT physiological footwear is like walking barefoot on springy moss or a sandy beach - a very comfortable feeling, but also challenging for the whole body. Because every step is a small workout for the entire body.
This training effect means that wearing MBT physiological footwear leads to a multitude of benefits: gait and posture improve significantly, relieving the pressure on the joints and back. A multitude of muscles is excercised both when walking and standing, which burns calories and stimulates the metabolism - stimulating weight loss and speeding up regeneration. MBTs also have a firming effect on abdominal, leg and buttock muscles.
So, that should give an idea of the company and its claims. Now, to address my first point, of whether this has anything to do with "barefoot technolocy," I go barefoot around the house and around my yard quite a bit, when I was a kid I used to go hiking barefoot through the woods, and I've been to the beach plenty of times. And I've gotta say, walking barefoot never seemed unstable. I mean, wearing shoes or going barefoot, you're still putting pressure on the same surface. Sand is soft if I'm barefoot or wearing shoes. And I don't see what difference this makes from the ankle up. If I stand barefoot on sand, my foot finds its equilibrium, and my body balances around my ankle. If I stand in shoes on sand, it's pretty much the same thing. So, calling this "barefoot technology," and using the Masai going barefoot as some type of validation of the technology, seems a bit silly to me.
Okay, let's just ignore the "barefoot" part. It's obvious just from one look that these shoes aren't normal. Is there something to this curved bottom sole that could have some therapeutic value?
To be fair, let's take a look at what the shoe company has to say. They have three studies listed on their website, all of which appear to have been commissioned by SwissMasai (warning - they're all pdf's):
- Changes in gait characteristics of a normal, healthy population due to an unstable shoe construction 8.1.2004 by Sheffield Hallam University
- In-Shoe Pressure Distribution in MBT shoes versus Flat-bottomed training shoes: a Preliminary Study 2.1.2005 by Laura Stuart, Edinburgh Royal Infirmary
- Effect of an unstable shoe construction on lower extremity gait characteristics 6.30.2004 by University of Calgary
The Sheffield study had 22 participants - 11 men and 11 women. To quote from the report, here is how the participants were outfitted:
On volunteering to take part in the study, each participant was provided with Masai Barefoot Technology (MBT) shoes (Figure 1.1) which were worn during the data collection sessions in the ‘MBT condition’ in addition to tight fitting shorts and vests. In the ‘normal condition’ participants were required to wear the same tight fitting clothing and their normal exercise shoes." And a little later in the report, "Prior to testing, participants were required to attend a tutorial session in which they were provided with their MBT shoes and instruction conforming to manufacturer’s specifications.
Here is the entire summary from that study:
The findings of the current study suggest that certain gait characteristics are affected during walking in a shoe of unstable construction. Although many of the kinematic variables remained unchanged, there were significant differences in both the trunk and the ankle angles. MBT shoes promote less forward lean during locomotion suggesting a more upright posture. Although not confirmed by the present study, the probable effect is a shift in the centre of mass position closer to the centre of the base of support, possibly aligning the body more optimally for locomotion. This, in conjunction with the lower hip moments experienced in the MBT condition may suggest reduced loading of the lower back. The changes in the ankle plantar flexion / dorsiflexion angle at the ankle, was primarily due to the reduced plantar flexion following initial contact during the MBT condition when compared to the normal condition. Kinetics at each of the joints of the lower limb were different between the MBT and normal conditions. The lower moments experienced at these joints suggests a resultant decrease in joint loading.
The major finding from analysis of the ground reaction force data is the suggestion that there is a higher incidence of transient peaks when wearing normal shoes compared to MBTs. There is some evidence suggesting that transient forces transmitted through the skeleton are the primary aetiological factor in the development of many musculoskeletal disorders. These include, osteoarthritis, stress fractures, plantar fasciitis and achilles tendonitis and low back pain (Whittle, 1999).
Muscular recruitment during MBT gait is also altered, eliciting an increase in motor unit recruitment for Gastrocnemius, Biceps Femoris and Gluteus Maximus and a decrease in Multifidus. The increased activity in the muscles of the lower limb can be attributed to differences in the mechanics of MBT gait, i.e. more upright posture and the production of greater propulsive forces during the dragging motion of the stance limb. Although not confirmed by this study, the decrease in multifidus recruitment may suggest that MBTs reduce the possibility of fatigue in the lower back.
This initial study into the effects of an unstable shoe construction suggests that MBTs alter certain gait characteristics and that with frequent use they may reduce the incidence of some musculoskeletal problems. In those already suffering from such disorders, MBTs may allow patients to remain mobile by reducing cyclic loading of the already damaged joint.
Here are a few excerpts from the Edinburgh Study, describing how participants were chosen & outfitted, and the results.
Ten healthy adults, 4 male 6 female, took part in this study, sampled by convenience.
All the participants were fitted with MBT shoes (Fig. 1A) in the correct size. In the control condition, participants wore their own flat- bottomed sports shoe (example in Fig. 1B)
Principal Results: Standing in the MBT shoes resulted in lower peak pressure in the midfoot (21%lower) and heel (11%) compared to in the control shoe, and much increased pressure in the toes (76%). The mean pressure was also increased in the toes and forefoot in MBT’s, and decreased in the midfoot and heel. Overall, compared to the control shoe MBT’s gave a pattern of pressure distribution that was shifted towards the front of the foot. However, more research is needed to assess their clinical application.
Thirdly, here are some excerpts from the Calgary Study:
Eight subjects participated in this study performing tests in a control shoe (Adidas SuperNova) and the illustrated MBT shoe (Fig. 1). A first test battery was performed during quiet standing, quantifying the movement of the center of pressure and the corresponding muscle activity. A second test battery was performed during walking, quantifying kinematics, kinetics, muscle activity (EMG), soft tissue vibrations and oxygen consumption for the two shoe conditions for walking in an initial testing session at the start of the project and two weeks later in a second session. Subjects were asked to wear the unstable test shoe as much as possible for the two weeks (9.5 ± 2.1 h) as suggested by the manufacturer.
- Standing in the MBT shoe produced more movement of the center of pressure and required more muscle activity in the lower extremity to balance the body. Thus, during standing, the MBT shoe acts as a muscle training device.
- The general walking kinematics were not changed by the MBT shoe except for the landing kinematics (flat foot) and the stride frequency (higher) and stride length (shorter).
- The rotational ankle joint impulse for plantar-flexion for the first half of stance is higher for the MBT shoe. However, the actual plantar flexion moments are small during the first half of contact time. Thus, this increase should not be of any concern.
- The rotational ankle joint inversion impulse for the first half of stance is substantially higher for the MBT shoe. Small changes in shoe construction could change this situation if desired.
- The rotational ankle joint impulses for all other joints and axes are slightly decreased with the MBT shoe. The reduction is consistent for the knee joint and is on the average for all axes 19%. This result and the results for the reduced or maintained muscle activity during walking are evidence that the MBT shoe produces movement close to the preferred movement path.
- The muscle activity of the major muscle groups shortly before and after heel strike was not changed with the MBT shoe with the exception of reduction of the tibialis anterior and biceps femoris muscles.
- The MBT shoe required 2.5% more oxygen consumption for the same walking task, a difference that can be explained primarily by the additional weight of the MBT shoe.
- The onset and the frequency of the soft tissue vibrations were influenced by the MBT shoe.
- It is speculated that the MBT shoe strengthens the small muscles with small levers with respect to the rotational axes. This would reduce the joint loading which could explain some anecdotal results of less pain and discomfort.
In summary, the results of this study showed that the MBT shoe
- acts as a muscle training device during standing and quasistatic activities and
- reduces knee and hip joint loading during walking.
Okay, I think I was pretty fair in presenting the studies' findings, which do look promising. However, there are a few things about the studies which do bother me. Admittedly, I'm not a doctor or a scientist, but I still think these are valid concerns.
First of all, the studies were small. Each one only had a handful of people. Sure, it's enough for a good initial test, but not as convincing as it would be for a larger group. This, though, is my smallest complaint.
Another issue for the Sheffield and Edinburgh studies, was the manner in which participants were outfitted with shoes. For the MBT shoes, the participants were fitted and given instruction. Yet, for the control group, it was whatever old athletic shoes they happened to own. They could have been $5 Wal-Mart brand shoes for all we know. Only in the Calgary study were participants given a standardized control shoe.
The biggest issue I had, wasn't with the studies per se, but in using them as a justification for endorsing this shoe. The problem is that the studies were too focused. Let me give an (absurd) analogy to illustrate this point. Consider somebody wanted to solve the problem of saving people from burning buildings. They identified that one of the ways that fire can kill people is by burning them. They also know that the fires are caused by a combustion reaction between oxygen and and the combustible materials in the house. So, they figure, that if they can eliminate the oxygen, the fire won't be able to continue, so it won't be able to burn people to death. They invent a machine that very rapidly pumps nitrogen throughout the building, displacing all of the air, removing all of the oxygen. They run some studies, and find that their invention does indeed displace the air in the building fast enough to put out the fire. Unfortunately, they missed the fact that by displacing all of the oxygen, the people in the building wouldn't be able to breathe, and so they'd all die, anyway.
Obviously, that's much more extreme than anything that would be happening with these shoes (I said it was an absurd analogy), but it illustrates the problem with these studies. The makers of MBT shoes have identified some problems (obesity, joint pain, etc.), found some of the causes of those problems, and have built a shoe to address those causes. They ran some studies, and looked specifically at whether or not their shoes were addressing those causes. Unfortunately, they weren't looking at the big picture, or for other possible side effects. The studies were too small and too short to determine what detrimental side effects might occur from prolonged use of the shoes. For something with such big claims, such as changing your entire posture and gait, and I'd want to be sure it was changing them for the better.
Okay, so that covers the studies listed on MBT's website. I was able to find one other study that looked at these shoes, as well as a mention in the procedings of a meeting of the Physiotherapy Research Society. Let's first take a look at the Proceedings of PRS Spring Meeting (warning-pdf). Here's the relevant excerpt from that document.
The effects of Masai Barefoot technology footwear on posture: an experimental designed study
P. New, J Pearce.
School of Health Professions & Rehabilitation Sciences, University of Southampton, United Kingdom.
Introduction: This study was approved by University of Southampton ethics committee and aimed to assess the anatomical changes to upright posture that occur in the sagital plane as a result of wearing Masai Barefoot Technology (MBT) footwear during standing and walking. MBT claim that their innovative unstable shoes promote a more upright posture in which musculature is strengthened and joint wear reduced . This could be helpful in the management and prevention of conditions such as osteoarthritis and back pain.
Subjects: 12 students (6 male and 6 female) at the University of Southampton aged between 18 and 40 participated in this study.
Methods: Participants attended one session at a biomechanics laboratory. The kinematics of posture wearing MBT shoes during standing and gait were examined using a twodimensional motion analysis system and compared to a control shoe.
Analysis: Statistical significance was tested using a pair ed t-test and a Wilcoxon signed ranks test.
Results: Standing in MBT footwear demonstrated a statistically significant increase in plantar flexion at the ankle joint (P = 0.025) [Mean 3.02 degrees, 95% Confidence Interval (CI) -5.6 to -0.4]. Walking in MBT’s showed a decrease in trunk flexion (P = 0.007) [Mean 1.44 degrees, 95% CI -2.4 to -0.4] and a reduction in anterior tilt of the pelvis, (P = 0.003) [Mean 3.20 degrees, CI -5.06 to -1.35] at heel strike. At toe off a significant reduction in anterior pelvic tilt (P = 0.035) was found in the MBT shoes [Mean 2.35 degrees, 95 % CI]. There was no significant difference found between the two shoe conditions at mid stance.
Conclusion: MBT footwear changes certain characteristics of posture in quiet standing and walking. These findings could have positive implications for the management of conditions such as osteoarthritis and back pain, however further research is needed.
The authors acknowledge support from Masai Barefoot Technology PLC.
1. Amann B, Amann F. Destabilise, sensitise, mobilise. Journal of Prevention and Rehabilitation. 2004; Special edition: 3-6.
I have the same feelings about this study as I did from ones listed on the MBT website - promising, but not in depth enough or over a long enough time interval to look for side effects.
So, let's move on to the study, Unstable Shoe Construction and Reduction of Pain in Osteoarthritis Patients, published in the October 2006 issue of Medicine & Science in Sports & Excercise Study, the official journal of the American College of Sports Medicine. I don't have access to the full text of the report, but here's the abstract:
Unstable Shoe Construction and Reduction of Pain in Osteoarthritis Patients.
Medicine & Science in Sports & Exercise. 38(10):1701-1708, October 2006.
NIGG, BENNO M. 1; EMERY, CAROLYN 2; HIEMSTRA, LAURIE A. 2
Purpose: The purposes of this study were to assess a) the effectiveness of Masai Barefoot Technology (MBT) shoe in reducing knee pain in persons with knee osteoarthritis (OA) and (b) changes in balance, ankle and knee ROM, and ankle strength compared with a high-end walking shoe for 12 wk.
Methods: The research design was a randomized controlled trial (123 subjects, knee OA). Subjects were randomized to a MBT (N = 57) or a control shoe (N = 66). A Western Ontario and McMaster Universities (WOMAC) OA index, BMI, balance, active ROM, and ankle torque were quantified at week 0, 3, 6, 9, and 12. Two-sample t-tests were done for between-group comparisons.
Results: There was no significant difference between groups in total pain score. A significant reduction over the 12-wk period was found for both shoe conditions (-42/500 or 25.6% MBT, -46.2 or 27.1% control). There was no significant group difference in pain during walking (t = -1.09, P = 0.28). Pain during walking was significantly reduced by 5.2/100 mm in the MBT and 9.7/100 mm in the control group. Total pain showed a significant reduction for the MBT -27.4/500 (-16.6%) and the control group -28.9/500 (-17.0%) between baseline and week 3. Between week 3 and 6, there was a significant reduction for the MBT group only (-27.2/500 or -20.0%). There was a significant increase in the static balance between baseline and 12 wk in the MBT group only, although the difference between groups was not significant.
Discussion: The results indicate that special shoe interventions can reduce pain in subjects with moderate knee OA.
(C)2006The American College of Sports Medicine
There is further discussion of this study at a site called Bondolier.
This is a study with a decent sized study group, a good control group, and lasted for a decent interval. I still would have liked to see more looking for side effects, but maybe that's too much for an initial study. Anyway, this study did show some good therapeutic value for the shoes, but it didn't seem to be much different from that achieved with a pair of conventional New Balance sneakers.
Finally, I was able to find a decent newspaper article that took a critical look at these shoes, Sole searching, datelined April 24, 2007, from The Guardian. The article starts off explaining the concept of the shoes, and lists the studies I've already addressed above. It then goes on to quote a few critics.
Nicki de Leon, a consultant physiotherapist at the sports and spinal clinic in Harley Street, believes that, for most wearers, MBTs can do more harm than good. "This footwear fundamentally alters the way someone walks, shifting their normal biomechanics so that instead of someone striking their heel to the floor and transferring the weight forward, they are effectively being rocked forward by their shoe." While not disputing that MBTs work some muscles harder, she argues that it is the wrong muscles that are tested. "What happens when you wear them is that the superficial muscles - such as the hamstrings, calfs and gluteal muscles in the legs and buttocks - are worked rather than the deep muscles that support the spine. When any superficial muscle is overworked, it becomes stiff and rigid, and that is precisely what I have seen happening in people wearing MBTs. I am not a fan of them at all."
Noel Kingsley, a leading practitioner of the Alexander Technique in London, agrees that the shoes are overrated. "They encourage a shorter stride than most of us are accustomed to. My concern is that this type of footwear lifts you quite high off the ground and requires you to walk in a special way. Once you get used to them, you feel quite odd without them. So what happens when you take them off?"
It is a question that also concerns de Leon. "A lot of people use them to walk distances, such as to work, but when you take them off your muscles forget what they are supposed to do. When you wear them, they change your alignment, but you don't know what's happening to your posture when you take them off and it's often not good."
In the long term, she says, the rigidity and stiffness of the muscles overworked by MBT shoes can cause pain and vulnerability to other injuries. "They are particularly risky for people with an existing unstable pelvis - quite a common problem - as they compound the instability. I really hope nobody runs in them as the outcome in terms of injuries could be dire." While MBT doesn't actively encourage running in its shoes, it doesn't discourage it either.
Actually, to address that last sentence, when I read Swiss Masai's FAQ, it said:
Yes, MBTs are perfect for jogging, as demonstrated in the video/DVD. MBTs are suitable for training but not for competitions. Always make sure that you are comfortable walking in them first, starting with the recommended time.
Going back to the Guardian article, here's another quote:
Alex Hazell, 28, from London started wearing MBTs four years ago. "At first I thought they were great, but then my physiotherapist pointed out that I was getting shoulder problems as the shoe was throwing me forward posturally. In the end I ditched them for a properly fitted training shoe."
They also quoted Sammy Margo of the Chartered Society of Physiotherapists, who said that MBT shoes could be useful, but added:
However, they don't work for everyone. For people who spend a lot of time at a desk, have hypermobility in their spine and weak core stability, MBTs could make their postural problems much worse.
And then, in the closing paragraph of the article:
Margo stresses that anyone intent on wearing MBTs "should definitely be doing a Pilates class or working on their core stability. Ideally you should get them only on the recommendation of a physiotherapist and should be trained to use them properly. They are not a cure-all for modern life".
So, after looking into the claims of Swiss Masai, it does appear that these shoes do show some promise for treating certain conditions. However, these were only preliminary - more clinical studies are needed. In the meantime, there is anecdotal evidence that the shoes can cause significant negative side effects. For anyone considering using these shoes, I would suggest that they talk with a physician or a physical therapist first, and then stay in contact with them to make sure that the shoes aren't doing them any harm.
Update I wrote a letter to the pharmacy where I first found MBT shoes, which I've posted online in this blog entry. Also, I received some feedback from a vendor of MBT shoes. Read the comments of that post to see his response.
Added 2009-01-19 I continue to receive comments on this entry on a fairly regular basis, a year and a half after I first posted it. Many have related positive experiences with the MBT shoes, and many have related negative experiences. So, I feel that I need to reference the popular saying - the plural of anecdote is not data. I do not mean to discourage people from posting their anecdotes here. In fact, I welcome them, because after all, that's what blogs are for. I just want to make it clear that without a proper clinical study, there's no way to quantify the risks associated with these shoes. So, to reiterate what I wrote before, if you plan on using these shoes, be aware that they do carry a risk for negative side effects, and be sure to consult closely with a doctor or physical therapist if you do use the shoes.