Compensation of stochastic time-continuous perturbations during walking in healthy young adults: An analysis of the structure of gait variability

•We analyzed the structure of variability in walking with and without perturbations.•Stochastic perturbations induced unstructured noise into the execution space.•Noise was predominantly compensated by means of improved covariation. During everyday locomotion, we cope with various internal or external perturbations (e.g. uneven surface). Uncertainty exists on how unpredictable external perturbations increase noise within the motor system and if they are compensated by employing covariation of the limb joints or rather due to decreased sensitivity of an altered posture. Do continuous stochastic perturbations affect the structure of gait variability in young and healthy adults? In a cross-over study, gait kinematics of 21 healthy young sports students were registered during treadmill walking with and without continuous stochastic perturbations. Using the TNC method, the following aspects were analyzed: (a) the sensitivity of body posture to perturbations (‘tolerance’) decreasing gait variability, (b) the unstructured motor ‘noise’ increasing gait variability and (c) the amount of ‘covariation’ of the limb joints. Compared to normal walking, gait variability was significantly increased (p