Gait analysis contributes to the identification of structural and functional limitations, as well as to the development of treatment plans and the evaluation of their effect on the patient. For this purpose, spatial and temporal characteristics of the patient's gait are studied and compared with reference values taken from control subjects. This paper examines the use of trajectories described by the instantaneous center of rotation (ICR) of the lower extremity segments as a biomechanical measure for assessing human gait. Gait trials were performed in which subjects walked on the ground and on a treadmill using a wearable inertial motion capture system (MVN Awinda, Xsens), while sports cameras recorded motion in the sagittal plane. Kinematic data from gait trials were acquired by video processing using an open source sports analysis tool (Kinovea) and directly through the Xsens Analyze software. The position of the ICRs of the lower extremity segments in the sagittal plane was calculated for each time sample and the determined trajectories were analyzed in time, frequency, and state space.