The Vibram Transition: Chapter 8 – Bone Marrow Edema & the Minimalist Transition

Steve AnkneyGeneral, Vibram Transition1 Comment

Recently, one of our writers, Jason, forwarded me a story he found on Runner’s World regarding a study by Sarah Ridge et al. that was published in February 2013 in the medical journal, Medicine & Science in Sports & Exercise.  The study is titled Foot Bone Marrow Edema after 10-week Transition to Minimalist Running Shoes.  Simply put, the study examines injury rates in a group of runners during a 10-week transition to Vibram FiveFingers.

The Article

The authors introduce us to the minimalist shoe concept similarly to how Born to Run opens the doors.  They cover the introduction of the traditional running shoe in the ’70s and then throw out some of the usual minimalist propaganda, and, once they get through all of the “go-to-points” for us minimalist runners, we get to the topic at hand.

The American Podiatric Medical Association (APMA) Position Statement on barefoot running states that it “has been touted as improving strength and balance, while promoting a more natural running style. However, risks of barefoot running include a lack of protection—which may lead to injuries such as puncture wounds and increased stress on the lower extremities. Currently, inconclusive scientific research has been conducted regarding the benefits and/or risks of barefoot running.”

…Due to the increasing popularity of minimalist running shoes, it is imperative that researchers, clinicians, and runners understand the potential risks present when transitioning from running in traditional running shoes to minimalist running shoes….

The study took place in Utah monitoring 36 recreational runners (21 male, 15 female) with an average age of 26.5 years.  In order to qualify to be included in this study, each runner had to be able to complete an average of 15 – 30 miles per week during a 6 month period.  Runners who had previously worn Vibram FiveFingers, or had a recent injury, were not included.  The group of runners was split up into two groups: one that would continue their regular training regimen in traditional shoes, and another that would gradually transition to FiveFingers by slowly replacing mileage in traditional shoes with mileage in FiveFingers, over a period of 10 weeks. The transition was a gradual one similar to that which is suggested by Vibram on their website.

Participants in the Vibram group were instructed to run one short (1-2 mile) run in the VFF during their first week of training. During the next 2 weeks, they were to run in the VFF for one additional short (1-2 mile) run each week, thus during week three, they would run at least 3 miles in the VFF.  

In order to better emulate a “real-life” transition, everything past the third week of the transition was decided by the athlete.  The authors wanted the runners to be able to evaluate their own comfort levels with running in FiveFingers and decide how to move forward with their individual transitions, whether it be slow down, or keep moving forward with their mileage in VFFs.

Here is where things start to get scary…

The post-training MRI scores [a range of 0-4, where a score of 0 indicated no injury and a score of 4 indicated a stress fracture] showed that more subjects in the Vibram group showed increases in bone marrow edema in at least one bone after the 10 weeks of running than in the control group.

In case you’re wondering, bone edema is excess fluid in the marrow.  This excess fluid is a way that the body responds to a recent injury.  By swelling the marrow, the body protects the recent injury from getting worse.  In the group transitioning to VFFs, 11 out of the 19 subjects were classified as injured at the end of the study, and two of them suffered from stress fractures!  This is shocking when compared to the control group, in which only 1 subject out of 16 was injured at the end of the study, and lead Ridge et al. to suggest that it was not the running to blame, but running in VFFs that was the cause of the foot bone injuries.


The last piece of information I gathered from this that I found especially interesting was the proportion of injuries for women relative to men during the minimalist transition.  Out of the 11 people injured, 8 were women, which would suggest that women may require a longer transition period in order to complete it safely.


This study examined the potential for stress injury by measuring the presence of bone marrow edema and soft tissue damage in the foot after runners transitioned to Vibram FiveFingers shoes throughout a 10 week transition period. The Vibram group had a significantly greater incidence of bone marrow edema after the training period, while neither group showed any soft tissue changes. Thus, to minimize the risk of bone stress injury, runners who want to run in VFF should transition over a longer duration than 10 weeks and at a lower intensity (miles per week) than the subjects in this study. 

This time, science is on our side when we say slow down your transition.  Be safe, and just because you think you can push through the pain, doesn’t mean you should.  This study suggests that a new minimalist runner should transition over a period of time that is slower than most people currently recommend in order to avoid injuries. I agree with the authors when they state that to accomplish an injury-free transition, your transition period should be longer than the 10 weeks

This was a very interesting story that really hit home for me and Meagan.  We’ve talked more often about our issues with calf-ocalypse, but, if you remember, we also dealt with pain related to bruising on our forefoot, and ankle and hip pain, all related to our transition period.  So, again, please believe us when we say “Take things slow.”  We promise it is in your best interest!

In regard to the study, I think the findings are significant to the minimalist community, but, frankly, I think there is a lot more to be done.  I’d like to see what a comparison between traditional shoes, FiveFingers, and single-toe-box minimalist shoes would look like, or how much walking, regularly (so that you are working on your transition not just when you are running, but also during your everyday activities), in a pair of minimalist shoes would affect the results.  I’d also like to find out more about the women in this study and their “shoe habits”.  I’m interested to hear if these women spend a large portion of their day-to-day lives in heels or other dress shoes.  The reason being that it is hard to believe there was such a difference between men and women in this study, and perhaps it was something like wearing heels everyday that prevented these women’s feet from healing properly between runs.  I think another complimentary study could cover the impact of transitioning to minimalist shoes and their long-term effects relative to traditional shoes on your calves, knees, hips, hamstrings, and lower back. Finally, it would be interesting to see a study where running form was controlled.  I’m curious to know if all of the runners were heel-strikers when wearing traditional shoes, or if some of them already ran with a midfoot/forefoot form, and also if the runners in the VFF group were monitored in any way to insure that they were running with proper form.  What else would you like to see studied?  Do you find any of the data covered in this story to be surprising or unlike what you may have expected?  Let us know in the comments!

Quotes from: Ridge et al., 2013, Foot Bone Marrow Edema after 10-Week Transition to Minimalist Running Shoes: Medicine and Science in Sports & Exercise (e-published ahead of print)