Evaluation of Biomechanical Characteristics of Bilateral Landing in Children with Different Levels of Coordination

Abstract

The purpose of the present study was a) to study the biomechanical characteristics (kinetic and kinematics) which influence the amplitude of maximum vertical ground reaction force (Fzmax), in bilateral landings in children and b) to examine differences in the kinetic and kinematic characteristics of bilateral landing from 20 cm height, among children with different levels of motor coordination. The Μovement Assessment Battery for Children (Henderson & Sugden, 1992) was used to assess the coordination level in 35 children (7-9 years old). Nine children (n=9) were reported to have motor coordination problems and formed the motor
coordination problems group (MCPG, Body weight: 37.22 ± 6.3 Kg, Body height: 142.22 ± 3.46 cm). Additionally, 9 children with typical coordination comprised the control group (CG, Body weight: 35.83 ± 7.9 Kg, Body height: 141.44 ± 7.67 cm). Groups were videotaped (Panasonic PV-900, 60 Hz) performing bilateral landings, dropping from 20 cm height, on a Kistler force platform (Type 9281CA, 1000Hz). The following kinetic and kinematic variables were assessed: vertical ground reaction force at first contact normalized to
body weight, (ΣΔ1= Fz-1 / BW), maximum vertical ground reaction force normalized to body weight, (ΣΔmax =Fzmax / BW), time for the ground reaction force to reach peak Fzmax, (tFzmax), landing time (tland), joint range of motion at ankle (Δφankle), knee (Δφknee) and hip (Δφhip). Pearson’s correlation analysis showed significant negative correlations between ΣΔmax and tFzmax and tland (p < .05), respectively, but significant positive correlations between tland and Δφknee and Δφhip, (p < .001), repectively. Multiple regression analysis was used to predict the maximal vertical ground reaction force by the other variables and the independent samples t-test to examine differences between groups, for all dependent variables (p<.05). According to regression analysis,
results showed that no model used, was able to effectively predict ΣΔmax. However, the negative correlation found between variables and ΣΔmax showed that high values of ΣΔmax correlated with short tFzmax and limited range of motion in the knee joint (Δφknee) Independent samples t-test showed significant effects of the group factor on ΣΔmax (p=.04), tland (p=.001) and Δφknee (p=.03). In conclusion children with motor coordination problems performed less safe landings, characterized by high vertical ground reaction forces, short landing times and limited knee joint range of motion. Results may be useful in the design of effective programs for the development of landing skill, both in school and sport club settings.