Children Display Adult-Like Kinetic Patterns in the Time Domain, But Not in the Frequency Domain, While Walking With Ankle Load.

This study used both time and frequency domain analyses to investigate walking patterns with ankle load in children and adults. Twenty-two children aged 7-10 years and 20 young adults participated in this study. Three levels of ankle load were manipulated: no load, low load (2% of body mass on each side), and high load (4% of body mass on each side). An instrumented treadmill was used to register vertical ground reaction force (GRF) and spatiotemporal parameters, and peak vertical GRFs were determined. A frequency domain analysis was conducted on the vertical GRF data. Results demonstrate that, in the time domain, children showed adult-like spatiotemporal parameters and adult-like timing and magnitude of the 2 peak vertical GRFs under each load. In the frequency domain, children produced a lower power from the second harmonic than young adults, although both groups showed the highest power from this harmonic and increased this power with ankle load. It was concluded that children aged 7-10 years may start showing adult-like neuromuscular adaptations to increasing ankle load and display similar spatiotemporal control of foot falls and foot-floor kinetic interaction; however, a frequency domain analysis is effective in revealing different kinetic and neuromuscular characteristics between children and adults.