A recent 10-week study found that 10 of 19 runners who switched to the Vibram FiveFingers running shoe showed signs of foot bone injury, while only one in 17 runners who wore conventional shoes exhibited the same injuries.
Background
To understand the effects of the Vibram FiveFingers shoe, researchers divided recreational runners into two groups. For the purpose of the study, the average age of a recreational runner was 26, and they averaged 15-30 miles a week. In order to be eligible for the study, no runner could have sustained an injury that prevented them from running at least three times a week over the last six months.
Method
Researchers asked the control group to continue their running pattern as scheduled, while the other group was asked to do some of their running in the Vibram FiveFingers.
Vibram FiveFingers are intended to be slowly integrated into a runner’s workout. As directed, participants began to transition to the VFF’s over a 10-week period. Runners were asked to replace one of their scheduled runs with a shorter (1-2 mile) run in the Vibram FiveFingers. Each week, they replaced one run with a shorter run in the new shoes, and then lengthened each run in accordance with the 10-week transition plan.
Findings
Researchers took MRIs of the runners’ feet before and after the study. Neither group showed changes in any soft tissue areas like tendons or plantar fascia.
However, researchers noted that there was a significant difference in bone readings among the two groups. MRI technology allowed researchers to view how much bone marrow edema was located in a participant’s foot. Bone marrow edema is essentially excess fluid buildup, which can indicate that the body is trying to swell around an injured portion. Researchers graded the edema levels on a scale of 0-4, where 2 or higher meant the runner was injured.
Through this process, researchers found that 10 of the 19 runners who used Vibram FiveFingers had suffered a bone injury, while only one of 17 runners in the control group suffered a similar injury. Moreover, two of the runners using the VFF’s had developed full blown stress fractures.
Conclusion
Researchers concluded that although minimalist shoes like the Vibram FiveFingers can strengthen muscles in the legs and feet, the lack of padding can lead to higher rates of injury. This study suggests that runners should take even more time than the suggested 10-week timeline to transition to the new shoe. Researchers also advised doing all introductory runs at a low intensity, which reduces the impact on the foot.
Dr. Silverman comments
The results aren’t surprising to me, mainly because they are taking runners who are untrained in the style of running in a minimalist style shoe and asking them to make steady change. Obviously there are going to be some adaptations that occur to a foot as people switch to the new strike pattern suggested in the Vibram FiveFingers.
If a person has been running on the heel of their foot, then suddenly they change strides and begin to land on the ball of the foot (which is much healthier), it’s going to take some time for the foot to strengthen and adapt.
I think it’s important to take away from the study that changes in running should be gradual. Spike Lee once said ‘it’s the shoes’, but in reality, they aren’t magic.
The main thing this study brings to light is a sense of respect of the need for slow, gradual change. Despite the small sample results, runners should not be inhibited from making the change if they are interested.
Related source: Runners World
