Attenuated intersegmental cancellation compromises whole-body angular momentum control during perturbed locomotion

The segment-to-segment angular momenta cancellation, a key regulatory mechanism for whole-body angular momentum control, was investigated during unperturbed level walking, unpredictable and adapted drop-like perturbations as well as during hole negotiation gait. Whole-body angular momentum and cancellation coefficients of segmental angular momenta were determined across the sagittal, frontal, and transverse planes in 18 participants. The peak-to-peak range of whole-body angular momentum was significantly higher (p < 0.001) in the perturbed walking conditions compared to unperturbed walking, with the greatest increase during unpredictable perturbations in all three planes (p < 0.001), indicating increased demands on angular momentum control. The cancellation coefficients of segmental angular momenta decreased significantly (p < 0.001) in the sagittal plane across all perturbed conditions compared to unperturbed walking, whereas in the transverse plane a significant decrease (p < 0.001) was observed only for the unpredictable drop-like perturbations. The cancellation coefficients in the frontal plane were the smallest among the three planes, with no significant differences observed across the investigated task conditions (p ≥ 0.165). The reduced intersegmental cancellation of angular momenta indicates an attenuation of a key coordination mechanism regulating whole-body angular momentum during perturbed walking. Experience with perturbations improves intersegmental coordination, primarily in the transverse plane. Finally, the consistently low and invariant intersegmental cancellation in the frontal plane indicates that this mechanism has limited regulatory capacity for whole-body angular momentum in this plane.