This week's "study of the week" is looking into the differences between running in a minimalist shoe or lightweight shoe versus running barefoot. I choose this study because of the recent popularity in past years to wear shoes that are suppose to simulated running barefoot. Much of this popularity due to the publishing of a book called Born to Run by Christopher McDougall. Just a fair warning this study was a bit on the difficult side to read through due to the biomechanical nature of the study. But I think it is important to understand the differences that are caused by running barefoot versus running shod. I am personally of the belief that the whole barefoot running movement is a bit romanticized about all the potential benefits. But this study does offer some interesting findings about stride length and stride frequency alterations when running barefoot.
Alright time to get to it! Let's nerd out!
published in the British Journal of Sports Medicine
Typical running shoes are made with heavily cushioned soles and elevated heels for the purpose of reducing impact when the runner's foot contacts the ground. These repeated impacts of this contact are believed to cause overuse injuries and thus by reducing the impact you protect against injuries. But in recent years there has been advocacy for running in shoes that simulate barefoot running or running barefoot period. Both camps assert benefits for their approaches including injury prevention. Though many of claims made by both proponents have little to no evidence to support them other than theory.
Previous researchers have studied barefoot running compared to shod running from a biomechanical perspective. Researchers found barefoot running involves a shorter stride length and reduced knee moments during stance. Other researchers found that barefoot runners use a less dorsiflexed ankle when making contact with the ground and tend to make contact with mid or fore foot strike, but not all studies looking at barefoot running have concluded this. But what is not known is whether or not shoes designed to mimic barefoot running actually do in fact involve similar biomechanics.
In order to investigate whether or not running in minimalist shoes produce similar biomechanics to someone running barefoot who is a habitual shod runner, the researchers recruited 22 trained runners (14 men and 8 women). The runners were made to run with four different types of footwear conditions including: barefoot, minimalist shoe which was a NIKE Free 3.0, a light weight racing flat shoe which was the NIKE LunaRacer2, and with a pair of self selected running shoes. Researchers took measurements of the subjects as the runners performed trials at 90 percent of their 10km times on a synthetic indoor running track. Researchers used a 22 camera motion analysis system and eight force plates to record movements and ground reaction forces of the runners during the performed trials. They then used inverse dynamics calculations to estimate joint moments then normalized these relative to individual body mass. In addition they calculated net joint powers as the product of the net joint moments and corresponding joint angular velocities
Reported mean running velocity across all conditions was 4.48 ± 1.6 m/s and there was no difference between the four different shod conditions. Stride length was shorter while stride frequency was higher when running barefoot compare to the other shod conditions. Stride length was shorter and stride frequency higher in minimalist and lightweight shoes than in self selected training shoe but no significant difference in minimalist or lightweight shoes. Stride length of barefoot running was 2.94m, mimimalist was 3.00m, self selected shoe was 3.04m, and lightweight shoe was 3.01m.
Researchers reported significant differences in joint angles at the ankle and knee, but no the hip. Significant differences between barefoot running and the other shod conditions included the following:
- peak knee flexion ankle in stance was lower in barefoot running at 48.57 degrees compared to 50.67 degrees in minimalist shoes, 50.67 degrees in lightweight shoes, and 50.97 degrees in self selected shoe
- ankle contact ankle was lower in barefoot running at 0.78 degrees compared with 4.52 in minimalist, 4.25 in lightweight, and 5.31 degrees in self selected shoe
- peak ankle dorsiflexion in stance was lower in barefoot running at 24.94 degrees compared with 26.09, 26.33, and 27.51 in minimalist, lightweight, and self selected training shoes, respectively.
- ankle plantar flexion at toe-off was greater in barefoot running at 10.91 degrees compared to 6.01 in minimalist, 4.77 degrees in lightweight, and 5.09 degrees in self-selected training shoe
- peak ankle adduction angle was much lower in both barefoot and minimalist shoes
Reseachers found significant differences in joint moments at both the ankle and the knee, but not the hip. Significant differences included:
- knee extension moments and knee abduction moments were both smaller in barefoot running compared to shod running of all types.
- Ankle plantar flexion moments and ankle internal rotation moments were greater in barefoot running than in shod running conditions
- running barefoot increased positive work at the ankle compared with all shod conditions.
- running barefoot decreased work at the knee joint
Researchers concluded strict barefoot running leads to changes in running mechanics of trained and habitually shod runners that are not comparable to what is produced by minimalist and lightweight shoes. They concluded that barefoot running involves a shorter stride length, less dorsiflexed ankle at ground contact, less flexed knee during stance, smaller knee extension moments and work done at knee, and larger ankle plantar flexion moments and work done at the ankle. Researchers hypothesized that these differences could be created by alterations in proprioception.
- subjects were all habitually shod runners who have many miles in both training and lightweight shoes, and some had significant experiences in minimalist shoes
- Barefoot was the only condition the subjects were unfamiliar with.
- used specific types of shoe and therefore the conclusions drawn may not apply to all minimalist shoes
- weights of each shoe was different, previous research has found that there is an effect of weight on the oxygen cost of running and there could also be an effect on joint ankle movements and moments.
Bonacci, Jason, Philo U. Saunders, Amy Hicks, Bill T. Vicenzino, and Wayne Spratford. "Running in a Minimalist and Lightweight Shoe Is Not the Same as Running Barefoot: A Biomechanical Study." British Journal of Sports Medicine (2013): n. pag. 11 Jan. 2013. Web. 11 Apr. 2013.
I hope you could suffer through all the boring jargon and results to get to the conclusion the researchers made. I think they offer some great insights and considerations to runners especially those with previous injuries either at the ankle or knee. I think this study of the week series is really important because I think as a community the health and fitness industry needs to be more evidence based. Although expert opinion and anecdotal evidence are forms of support they are not equal to research done in a controlled environment. Though as a caveat I will admit research is often times behind in proving what works and what doesn't work so that those in the field often are ahead of the findings of research in terms of doing what is most effective, but it is important to stay current so that we can use the new literature to evaluate our methods of training clients and improve upon them or judge them obsolete altogether.
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