Figure 6:

Coupling between lateral foot placement at one footfall and the external rotation at a lag of a number of strides later (or earlier). Coupling is defined as angle of covariance axis between lateral placement and rotation (mean ± S.D. across all strides and subjects). Coupling was significant (P < 0.01) for lag of 0 (current stride), and for lag +1(succeeding stride) which was smaller and negative. This may indicate a balance correction at stride 0, with a subsequent overall heading correction back towards a forward walking direction at stride 1.