2013-Bonacci-Running in a minimalist and lightweight shoe is not the same as running barefoot- a biomechanical study

Very interesting paper about running biomechanics between different shoe conditions. A solid methodology was used, with a 1-week familiarization period for the 4 conditions (barefoot, Nike Free 3.0, Nike Luna Racer 2, usual shoe). Well-trained runners ran on a 110 meters indoor track section, on which a 20-meter section was equipped with a VICON camera system. Interesting data about the ankle angle at foot strike is provided, as to quantify the degree of heel striking. Barefoot running was different to all shod conditions. Barefoot running changes the amount of work done at the knee (decrease) and ankle (increase) joints and this may have therapeutic and performance implications for runners. See Table 2 for interesting data.
Opinion: We think that this study is great, as it shows that whatever type of shoe you are wearing, you can't replicate the barefoot condition. Biomechanics during barefoot running showed less heel strike, less knee flexion at midstance, lesser joint moments and work done at the knee and more at the ankle, compared to shod running, even in minimalist shoes. However, the definition of minimalist is so wide that the Vibram FiveFingers (TRC rating of 90%) and the Nike Free and Luna Racer (TRC rating of 66%) used in this study are very different, even if they are all advertised as minimalist. For sure the neurophysiological effect of plantar skin feeling induces most impact moderating behaviors, but we are pretty sure that using these same shoes in a study involving recreational runners would have produced different results. Subjects in this cohort were 14 male and 8 female runners with an average time of 33 min 40 sec on a 10km and an average weekly running distance of 105,3km. We could hypothesize that these runners have learned the optimal biomechanics for them and developed running economy through hours of practice, therefore a change in shoes would not induce impressive biomechanical modifications. For example, step frequency was 181 at first, but even increased up to 187 by reducing the distance between the foot and the ground. The average ankle angle at contact still changed from a slight heel strike to a midfoot strike (5.31, 4.25, 4.52 and 0.78 degrees for regular shoes, racing flats, minimalist shoes and barefoot, respectively) when going towards barefoot. Recreational runners with an ankle angle at contact of more than 15 degrees (which is more than common) have more potential to modify their biomechanics when getting closer to barefoot. The goal of this study was to evaluate such intervention in well-trained runners, which was achieved successfully. Further studies should replicate such design on recreational runners.
It reminds us of a blog post that provoked a lot of reactions: Click here to see.