Toning or unstable shoes do not exactly have much of good track record due to the exaggerated health claims that got made for the product and the multi-million dollar settlements that some of the manufacturers had to enter into. This was based on the lack of evidence for those health claims. That does not mean that these types of shoes are not useful and have some benefits. The underlying principle of this category of footwear is that they are deliberately designed to be unstable via the incorporation of different design features, such as a rocker sole to induce changes in muscle activity and gait characteristics. Different manufacturers do it differently.
Generally, the lab based research on these types of shoes certainly do show that they induce changes. However, the outcomes from clinical trials to translate those mechanical changes into health benefits is limited and this lack is what has underpinned the legal issues faced by the manufacturers. The benefits are largely theoretical, but are also probably real. My own clinical experience is that, yes, the change in gait characteristics and muscle activity does appear to help some people with gait and postural problems; but, unfortunately they also tend to hurt other people. I can’t say I have seen any consistent pattern to predict who they will or will not help. Personally, I do wear my MBT’s one day a week, purely to mix things up, to use different tissues differently. Theoretically, that probably sounds like a good idea. There is certainly a need for more clinical trials to help inform which clinical conditions will benefit. For example, the rocker action of these shoes could be helpful for conditions such as osteoarthritis of the first metatarsophalangeal joint and a number of clinicians use them for that (and there is a clinical trial looking at this). There is plenty more on toning shoes here.
In that context, it was good to see a trial on the use of this type of footwear to see if by altering the gait, could they affect the post-marathon recovery:
Post-marathon wearing of Masai Barefoot Technology shoes facilitates recovery from race-induced fatigue: an evaluation utilizing a visual analog scale
Nakagawa K, Obu T, Kanosue K
Open Access Journal of Sports Medicine December 2014 Volume 2014:5 Pages 267—271
Purpose: To investigate the potential benefit of post-race wearing of unstable shoes (Masai Barefoot Technology [MBT]) on recovery from marathon race–induced fatigue.
Patients and methods: Forty-five runners who participated in a full marathon race were divided into three groups: 1) MBT shoes, 2) trail running shoes, and 3) control (CON). Participants ran a full marathon with their own running shoes, and then put on the assigned shoes immediately after the race. They continued to wear the assigned shoes for the ensuing 3 days. The CON group wore their usual shoes. Estimates of post-race fatigue were made by the participants on questionnaires that utilized a visual analog scale. Estimates were made just after the race, as well as for the next 3 days.
Results: The subjective fatigue of the MBT group was lower than that of the CON (P<0.05) or trail running shoe groups (P<0.05) on day 3.
Conclusion: MBT shoe intervention can promote recovery from the fatigue induced by running a full marathon.
The full text is available at the link above. On the surface this looks like a good idea. The MBT shoes are going to make the gait somewhat different and use the fatigued muscles in a different way. The theory that these shoes could facilitate recovery following a marathon is plausible.
However, there are a number of flags that need to be raised:
- the participants were not randomized into the three groups, but “were divided into the three groups described earlier. Based on pre-questionnaires, the groups were matched for foot size and targeted race time“. As this was a prospective study, the participants should have been randomized and not matched. It is not clear exactly how they did the matching, but the lack of randomization introduces bias.
- The group assigned to the MBT shoes were given “a short lecture on how to use the MBT shoes“. This means that they probably knew that they were in an intervention group and not in the control group. Participants in trials should be blinded to avoid the potential for biases.
- The authors claim that statistical testing showed no differences between the 3 groups in their marathon time, except that when I look in the table, the control group on average was about 30 minutes slower than the two intervention groups and with a small standard deviation, I not sure how they managed to not find a difference between the 3 groups (check table one and tell me what you think). I not saying that its not, but I am concerned about that, as that could suggest that the control group consisted of less experienced runners and this would affect post marathon recovery.
- The main analysis appears to be done by determining “differences in fatigue among the three groups on day 3 were also examined by unpaired t-tests” which is not how you analyse a trial with three groups.
- The authors did mention a number of other minor limitations to the study, that I will not mention here (see pg 270 in the full paper), but they do not affect the interpretation of the results like the ones I mentioned above (that the authors did not acknowledge!).
The graph of the results does look as though there was a difference between the three groups on day 3:
The authors concluded that:
Using MBT shoes during everyday activities promoted recovery from the exhaustive fatigue induced by running a full marathon
The question has to now be asked, does the data support the conclusion? I am not convinced it does. There are several sources of bias in this trial that either mean the conclusion is not supported or very weakened. The analysis of the data appears to have been done wrong. On the other hand the graph does show an apparent difference (keeping in mind the biases).
I not sure what to conclude, I am in two minds. I want to beleive. I like the theory behind toning shoes. I personally use them. The theory behind this study is plausible. However, the whole idea of critical thinking and science, in general, is to not let our personal biases influence the interpretation of the science.
As always, I go where the evidence takes me until convinced otherwise, and on this occasion I will have to conclude that the data does not support the conclusions due to too many issues with the study. The authors conclusion of “can”, should at the very least be downgraded to “may”.
Nakagawa, K., Obu, T., & Kanosue, K. (2014). Post-marathon wearing of Masai Barefoot Technology shoes facilitates recovery from race-induced fatigue: an evaluation utilizing a visual analog scale Open Access Journal of Sports Medicine DOI: 10.2147/OAJSM.S72509