Initiating running barefoot: Effects on muscle activation and impact accelerations in habitually rearfoot shod runners

Abstract

Runners tend to shift from a rearfoot to a forefoot strike pattern when running barefoot. However, it is unclear how the first attempts at running barefoot affect habitually rearfoot shod runners. Due to the inconsistency of their recently adopted barefoot technique, a number of new barefoot-related running injuries are emerging among novice barefoot runners. The aim of this study was therefore to analyse the influence of three running conditions (natural barefoot [BF], barefoot with a forced rearfoot strike [BRS], and shod [SH]) on muscle activity and impact accelerations in habitually rearfoot shod runners. Twenty-two participants ran at 60% of their maximal aerobic speed while foot strike, tibial and head impact accelerations, and tibialis anterior (TA), peroneus longus (PL), gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) muscle activity were registered. Only 68% of the runners adopted a non-rearfoot strike pattern during BF. Running BF led to a reduction of TA activity as well as to an increase of GL and GM activity compared to BRS and SH. Furthermore, BRS increased tibial peak acceleration, tibial magnitude and tibial acceleration rate compared to SH and BF. In conclusion, 32% of our runners showed a rearfoot strike pattern at the first attempts at running barefoot, which corresponds to a running style (BRS) that led to increased muscle activation and impact accelerations and thereby to a potentially higher risk of injury compared to running shod.

Impact Acceleration During Prolonged Running While Wearing Conventional Versus Minimalist Shoes

“…In agreement with other studies which showed that runners reduce their step length (our study 2.12 m MS vs 2.17 m CS/Bonacci 3.00 m MS vs 3.04 m CS/Squadrone 2015 2.29 m MS vs 2.34 m CS) and increase their stride frequency to maintain their running speed when using MS or running barefoot (our study 96.6 stride/m MS vs 94,2 stride/m CS/Bonacci 183.9 stride/m MS vs 181.9 stride/m CS/Squadrone 2015 85.4 stride/m MS vs 83.4 stride/m CS) (Bonacci et al, 2013;De Wit et al, 2000;Divert et al, 2005Divert et al, , 2008Lucas-Cuevas, Priego Quesada, et al, 2016;McCallion et al, 2014;Squadrone & Gallozzi, 2009;Squadrone et al, 2015), our results show that the type of footwear used directly affected the spatiotemporal variables (stride frequency and length of our participants). Thus, stride length is decreased to reduce the impact forces experienced with MS; leading to a better impact attenuation which is absorbed, to a large extent, by the musculoskeletal system.…”

“…Thus, we hypothesize that the decrease in the effective mass among runners using MS with respect to those using CS (MS < effective mass < CS) may result in an increase the tibial acceleration peaks (Derrick et al, 2002), which would concur with our finding that these values were higher among runners who wore MS during our study. In this sense, Lucas-Cuevas, Priego Quesada, et al (2016) also found that the maximum tibial acceleration peak was higher while RF strikers ran barefoot, even when the participants had no previous experience with barefoot or MS running.…”

“…In line with other studies, we did not observe any alterations in the maximum peak acceleration between the standard and extended running-period conditions; thus, the magnitude of the impact acceleration was higher with the use of MS. In this sense, Lucas-Cuevas, Priego Quesada, et al (2016) showed that this peak was increased in unexperienced barefoot runners compared those wearing CS, resulting in an increased risk of some types of impact injury, including lower-extremity stress fractures. No significant differences were observed in the headacceleration magnitude, but attenuation was higher with the use of MS (Figure 3).…”

“…The main objective of this study was to analyze the effect of MS and CS on spatiotemporal stride and acceleration parameters in runners experienced in the use of MS. To date, very few studies have analyzed accelerometry in combination with the use MS or CS (Chambon, Delattre, Guéguen, Berton, & Rao, 2014;Lucas-Cuevas, Priego Quesada, et al, 2016). A large prospective survey study suggested that barefoot runners report fewer running injuries compared to shod runners (Altman & Davis, 2016), however clinical trials suggest that changing from CS to MS is associated with increased running injury risk (Fuller et al, 2017;Ryan, Elashi, Newsham-West, & Taunton, 2014).…”

“…These impact accelerations are transferred through the body to the head via the different segments of the musculoskeletal system, and can affect the lower extremities or cause overload injuries (Abt et al, 2011;Milner, Ferber, Pollard, Hamill, & Davis, 2006). Several mechanisms can affect these impacts acceleration while running, including fatigue, the initial ground foot-strike pattern, and footwear type used (Lucas-Cuevas, Priego Quesada, et al, 2016).…”