A unilateral powered exoskeleton (Motorized ankle-foot orthosis, MAFO) is presented in this work, with the aim of studying muscle and kinematics short-term adaptations of the ankle during rehabilitation tasks. For this purpose, we conducted this study during gait over a treadmill, measuring surface electromyography activation and biomechanical data, in different conditions of assistance. This pilot study also aims to demonstrate that the tool is suitable for measuring biomechanical data while allowing EMG measurements, proving it as a useful tool during gait assessment and rehabilitation. Gastrocnemius Medialis activation presents slightly higher amplitude with higher assistances, so the subjects performed a higher range of motion gait pattern. Tibialis Anterior EMG activation presents consistent data with previous studies. Ankle angle at lower assistances makes the robot force less the subject to reach the imposed gait pattern, and so the range of motion diminishes. Regarding ankle angular velocity, at higher assistances, higher velocities are reached. The torque between the subjects foot and the robot. For lower assistances, the imposed reference pattern is less restrictive, and so the force the user exerts against the robot is lower.