Barefoot vs running shoes – Comparing 20m sprint performance, spatiotemporal variables and foot strike patterns in schoolchildren in the Western Cape

[摘要] ENGLISH ABSTRACT : A short anaerobic sprint test such as a 20m sprint test forms part of many fitness testbatteries used by sports teams and in schools during physical education classes forfitness testing. Some of these short sprint tests are done on a hard running surfaceand some of the protocols do not specify or standardise the type of footwear thatshould be worn and participants have a choice to sprint either barefoot (BF) or inrunning shoes. Similarly, many children and adolescents in South African schoolsparticipate in athletics competitions that are sometimes held on synthetic athleticstracks and since most children and adolescents do not own spikes, they have tochoose between competing BF or in their running shoes. In some countries such asSouth Africa, which has a BF culture, sprinting BF is common. Currently, there islimited research available to answer whether it is faster to sprint BF or shod.The aim of the current study was to determine the acute effects of sprinting BF andin running shoes on 10m and 20m sprint performance, spatiotemporal variables andfoot strike pattern (FSP). 115 Girls and 161 boys (N=276) aged 8-19 years fromrandomly selected schools in the Western Cape Province were recruited for the study.Children performed two 20m maximal effort sprints from a standing start on a hardrunning surface in both a BF and running shoes condition in random order. For eachsprint, 10m and 20m sprint times, step frequency (StepF), stride length (SL), flighttime (FT), ground contact time (GCT) and swing time (SwT) were measured and FSPwas determined. Sprint times were measured with electronic photocells (BrowerTiming Systems, Salt Lake City, UT) and spatiotemporal variables were measuredwith the OptoGait system (Microgate S.r.I, Bolzano, Italy). High-speed video footagewas taken with a GoPro camera (GoPro HD Hero 4, GoPro Inc., San Mateo,California, USA) at 240Hz and was analysed with video analysis software (Kinovea0.8.15) to determine FSPs. The data of the fastest sprint in each footwear conditionwas used for further statistical analysis.Statistically significant differences as well as small to medium practically significantdifferences were found between the BF and shod conditions for children andadolescents' 10m and 20m sprint performance and all the measured spatiotemporalvariables. When BF, children and adolescents' 10m and 20m sprint performances were significantly faster (p<0.001) but with only small effect sizes (d=0.24 and d=0.25respectively). The faster sprint performances when BF were due to a significantlyhigher StepF (p<0.001) with a medium effect size (d=0.42) despite beingaccompanied by a significantly shorter SL (p<0.001) with a medium effect size(d=0.73). The significantly higher StepF when BF was due to a significantly shorterFT (p=0.022) with a small effect size (d=0.16), a significantly shorter GCT (p<0.001)with a medium effect size (d=0.69) and a significantly shorter SwT (p<0.001) with amedium effect size (d=0.56). All differences in sprint performance and spatiotemporalvariables were due to the shoe mass effect and not due to FSP differences causedby the footwear effect. Changing from the shod to the BF condition caused asignificant decrease in the occurrence of a rearfoot strike (RFS) from 57% to 27%and a significant increase in the occurrence of a forefoot-/midfoot strike (FFS/MFS)from 43% to 73% (p<0.001). The shod condition, therefore, encouraged a significantlyhigher rate of RFS and the BF condition a significantly higher rate of FFS/MFS.In conclusion, changing from running shoes to BF has a significant acute effect onshort anaerobic sprint performance, spatiotemporal variables and FSPs of schoolagedchildren. Sprinting BF is only marginally faster than sprinting in running shoesover 10m and 20m but this may potentially only be applicable to habitually BF childrenand adolescents. Sprinting BF or in running shoes is, therefore, almost the samespeed and children and adolescents can choose either footwear condition for sprinttests of fitness batteries and for athletics competitions held on synthetic athleticstracks. Caution should be taken when acutely changing to sprinting BF since itincreases the risk of plantar surface injuries.

[发布机构] Stellenbosch University