Minimal detectable change for gait variables collected during treadmill walking in individuals post-stroke

Post-stroke gait impairments are common and result in slowed walking speeds and decreased community participation post-stroke. Treadmill training has recently emerged as an effective gait rehabilitation intervention. Furthermore, kinematic and kinetic data collected during treadmill walking are commonly used for assessing gait performance. The minimal detectable change (MDC) for gait variables provides a useful index to determine whether the magnitude of change in gait produced after an intervention is greater than the amount of change attributable to day-to-day variability in gait or test-retest measurement errors. The MDC values for kinematic, ground reaction force (GRF), spatial, and temporal variables collected during treadmill walking post-stroke have not been previously reported. The objective of this study was, therefore, to compute MDCs for post-stroke gait kinematics, GRF indices, temporal, and spatial measures during treadmill walking. Nineteen individuals with chronic post-stroke hemiparesis (12 males; age=47-75 years; 72.6±63.4 months since stroke) participated in 2 testing sessions separated by 20.7±26.8 days. Our results showed that test-retest reliability was excellent for all gait variables tested (intraclass correlation coefficients=0.799-0.986). MDCs were reported for hip, knee, and ankle joint angles (range 3.8° for trailing limb angles to 11.5° for hip extension), peak anterior GRF (2.85% body weight), mean vertical GRF (4.65% body weight), all temporal variables (range 3.2-4.2% gait cycle), and paretic step length (6.7 cm). These MDCs provide a useful reference to help interpret the magnitudes of changes in post-stroke gait variables.