Day-to-Day consistency of lower extremity kinematics during walking and running. 
Before conclusions can be drawn with respect to the quality of adaptations in human gait, the day-to-day consistency of the variables of interest must be known.  The present study estimated the day-to-day consistency of kinematic variables collected during barefoot walking and running.  Sixteen healthy subjects performed two gait analysis sessions based on skin markers.  Test sessions were at least 1 week apart.  In total, 48 ranges of motion were monitored for the hip, knee, ankle, and midfoot joint.  Based on differences between the repeated gait analysis sessions, the day-to-day consistency was estimated.  It was found that the day-to-day consistency was of the magnitude of 3 to 4 degrees for almost all ranges of motion independently of the test condition, the investigated joints, or the cardinal body plane.  It was concluded that future studies on effects of interventions or on the characterization of pathological versus normative gait should consider the provided values of day-to-day consistency to improve their interpretation and conclusions.