Spatial characteristics of reactive stepping among people living with chronic incomplete spinal cord injury.

Objective: Compare the spatial characteristics of reactive stepping between individuals with chronic motor incomplete spinal cord injuries (iSCI) and able-bodied (AB) individuals.Design: Cross sectional.Setting: Lyndhurst Centre.Participants: Twelve individuals with iSCI (3 males, 53.6 ± 15.2 years old) and 11 age- and sex-matched AB individuals (3 males, 54.8 ± 14.0 years old).Interventions: The Lean-and-Release test was used to elicit reactive stepping. A horizontal cable, attached at waist height, was released when 8-12% body weight was supported in a forward lean position. Participants underwent up to 10 Lean-and-Release trials in a session. Kinematic and kinetic data were recorded.Outcome measures: The length, width and height of the first reactive step of each trial were calculated. Standard deviation between trials was calculated to represent the variability in step length, width and height within a participant. Among participants with iSCI, correlation coefficients were used to explore the relationship between step length and width variability and (1) Lean-and-Release test behavioral responses, (2) 3-month fall history, and (3) lower extremity strength.Results: Step length (P = 0.94), width (P = 0.52) and height (P = 0.97), normalized for participant height, did not differ between groups. Participants with iSCI showed greater variability in step length (P = 0.02) and width (P = 0.01), but not height (P = 0.32). No correlation was found between step length or width variability and behavioral responses, 3-month fall history, or lower extremity strength.Conclusions: Individuals with iSCI showed increased variability in length and width of reactive stepping compared to AB individuals, which may contribute to their impaired ability to execute single-step reactive responses.Trial registration: ClinicalTrials.gov identifier: NCT02960178.