Browsing by Author "Murphy, Ian Desmond"

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    Barefoot vs running shoes – Comparing 20m sprint performance, spatiotemporal variables and foot strike patterns in schoolchildren in the Western Cape
    (Stellenbosch : Stellenbosch University, 2017-03) Murphy, Ian Desmond; Venter, Ranel; Stellenbosch University. Faculty of Education. Dept. of Sport Science
    ENGLISH ABSTRACT : A short anaerobic sprint test such as a 20m sprint test forms part of many fitness test batteries used by sports teams and in schools during physical education classes for fitness testing. Some of these short sprint tests are done on a hard running surface and some of the protocols do not specify or standardise the type of footwear that should be worn and participants have a choice to sprint either barefoot (BF) or in running shoes. Similarly, many children and adolescents in South African schools participate in athletics competitions that are sometimes held on synthetic athletics tracks and since most children and adolescents do not own spikes, they have to choose between competing BF or in their running shoes. In some countries such as South Africa, which has a BF culture, sprinting BF is common. Currently, there is limited 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 and in running shoes on 10m and 20m sprint performance, spatiotemporal variables and foot strike pattern (FSP). 115 Girls and 161 boys (N=276) aged 8-19 years from randomly 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 hard running surface in both a BF and running shoes condition in random order. For each sprint, 10m and 20m sprint times, step frequency (StepF), stride length (SL), flight time (FT), ground contact time (GCT) and swing time (SwT) were measured and FSP was determined. Sprint times were measured with electronic photocells (Brower Timing Systems, Salt Lake City, UT) and spatiotemporal variables were measured with the OptoGait system (Microgate S.r.I, Bolzano, Italy). High-speed video footage was taken with a GoPro camera (GoPro HD Hero 4, GoPro Inc., San Mateo, California, USA) at 240Hz and was analysed with video analysis software (Kinovea 0.8.15) to determine FSPs. The data of the fastest sprint in each footwear condition was used for further statistical analysis. Statistically significant differences as well as small to medium practically significant differences were found between the BF and shod conditions for children and adolescents’ 10m and 20m sprint performance and all the measured spatiotemporal variables. 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=0.25 respectively). The faster sprint performances when BF were due to a significantly higher StepF (p<0.001) with a medium effect size (d=0.42) despite being accompanied 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 shorter FT (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 a medium effect size (d=0.56). All differences in sprint performance and spatiotemporal variables were due to the shoe mass effect and not due to FSP differences caused by the footwear effect. Changing from the shod to the BF condition caused a significant 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 significantly higher 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 on short anaerobic sprint performance, spatiotemporal variables and FSPs of schoolaged children. Sprinting BF is only marginally faster than sprinting in running shoes over 10m and 20m but this may potentially only be applicable to habitually BF children and adolescents. Sprinting BF or in running shoes is, therefore, almost the same speed and children and adolescents can choose either footwear condition for sprint tests of fitness batteries and for athletics competitions held on synthetic athletics tracks. Caution should be taken when acutely changing to sprinting BF since it increases the risk of plantar surface injuries.