TauG-guidance of dynamic balance control during gait initiation across adulthood.

Measurements from force plates were investigated to identify the life-span developmental course of dynamic balance control during gait initiation across adulthood. Center of pressure (CoP) data of the initial weight shift onto the supporting foot in the mediolateral (CoP(x)) direction were tauG analyzed, investigating the hypothesis that tau of the CoP(x) motion gap (τ(CoPx)) is tau-coupled onto an intrinsic tauG-guide (τ(G)), by maintaining the relation τ(CoPx)=Kτ(G), for a constant K. Participants were in their twenties, forties, sixties, and eighties. As regression analysis suggested a strong linear relationship between τ(CoPx) and τ(G), an investigation of the regression slope as an estimate of the coupling constant K in the tau-coupling equation was justified. Mean K values increased significantly with age from 0.40, 0.47, 0.67, to 0.79, suggesting that control of dynamic balance deteriorates from participants in their twenties making touch contact (K≤0.5) to participants in their sixties and eighties colliding with the boundaries of the base of support (K>0.5). The findings may prove useful as a measure for testing prospective balance control, a helpful tool for early detection of elderly people at increased risk of falling.