Nordic walking alters orientation weighting but not dimensionality in lower-limb coordination

Using a within-subject experimental design, we tested whether Nordic walking preserves the low-dimensional coordination of lower-limb elevation angles while reallocating roles within that structure in twelve healthy adults. Participants walked at their preferred speed with and without poles on an indoor walkway after standardized instruction. Segment elevation angles (thigh, shank, foot) were obtained with markerless motion capture and processed in OpenSim. Planar covariation quantified coordination: planarity as the variance explained by the first two principal components (VAF_PC1 + VAF_PC2), plane orientation via the direction cosines of the PC3 normal with segment axes (U_3t, U_3s, U_3f), and in-plane allocation as each segment's squared loading on PC1 (Thigh_PC1, Shank_PC1, Foot_PC1). Separate paired t-tests were used to test differences on dependent variables between Nordic and normal walking. Planarity showed no difference (p = 0.689, d =  - 0.12). VAF_PC1 showed no difference (p = 0.065, d = 0.59), whereas VAF_PC2 was significantly lower during Nordic walking (p = 0.041, d =  - 0.67). Orientation shifted toward the thigh axis with U_3t significantly further from 0 (p = 0.002, d =  - 1.21), while U_3s and U_3f showed no difference (p = 0.814, d =  - 0.07; p = 0.064, d = 0.60). In-plane allocation reweighted proximodistal roles. Thigh_PC1 increased (p = 0.006, d = 0.98), Shank_PC1 showed no difference (p = 0.680, d = 0.12), and Foot_PC1 decreased (p = 0.001, d =  - 1.28). Together these results indicate that Nordic walking maintains a two-component coordination pattern while rotating plane orientation toward the thigh and shifting in-plane emphasis from the foot to the thigh, suggesting that pole use may modify segmental emphasis without altering coordination dimensionality.