2016 Volume 2016 Issue 73 Pages 13-19
Purpose：The purpose of this study was to compare the difference of characteristics of sprinting between barefoot and shod conditions, in relation to jumping abilities in children.
Method：94 children aged 6-12 years performed short sprints (30 m), counter movement jumping (CMJ) as a non-ballistic jumping and five repeated-rebound jumping (RJ) as a ballistic jumping. Sprinting conditions were randomized for each child in order to compare barefoot sprinting with shod conditions. High speed camera with 1/1000 second shutter speed was used to record calibration marks and performances of the children at a frame rate of 300 frame/second. The cameras were placed 20 m apart from the motion plane. Besides 5 video cameras from 5 angles obtained images of entire stance phase (right before foot strike to taking the toe off). Foot strikes were classified into 3 patterns：rear-foot strike (RFS) that land on the heel, mid-foot strike (MFS) that land with a flat foot, and fore-foot strike (FFS) that land on the fore-foot before bringing down the heel. Jumping abilities were assessed using CMJ jumping height and the value obtained by dividing jumping height by the ground contact time in 5RJ (RJ-index).
Results and Discussion：Under barefoot condition children significantly sprinted with lower velocity (p<0.05), higher step frequency (p<0.01), shorter step length (p<0.01) and shorter contact time (p<0.01). Additionally, barefoot condition induced the shift of ground contact manner from RFS to FFS and MFS. Children who sprinted faster with barefoot had higher jumping abilities than children who sprinted faster with shoes. Increased percentage of FFS and MFS in barefoot sprinting appears to enhance the utilization of elasticity produced in arches and Achilles tendon, which may affect positively to sprint performance for children who sprinted faster with barefoot. The result also indicated that jumping ability is higher in children who sprinted faster with barefoot. Our finding suggested that common factor could have effect on the ability of barefoot sprinting and jumping in children.
