## 2 Material and Methods
### Knee Kinematics Assessment  
Participants were assessed by a blinded operator for knee kinematics during walking at 1 week before the training start (T0), before (T1-pre) and 5 min after (T1-post) the first training session, and before (T2-pre) and 5 min after (T2-post) the last training session (Figure 1). During each evaluation session, participants were asked to walk barefoot on a treadmill for 120 s at a comfortable speed, previously estimated using the 10-m walking test and maintained unchanged for all the assessments [23]. Subjects were instructed to look straight in front of them and to not lean their hands on the treadmill during walking [24].  
Knee kinematics during walking was detected using an optoelectronic system (BTS SMART-DX, BTS, Milano, Italy) equipped with 8 infrared cameras (sampling rate 100 Hz) placed around the treadmill in the standard position of a rectangular room. Two clusters of five retro-reflective markers were placed on the lateral surface of the thigh (equidistant between the greater trochanter and the lateral condyle of the femur) and shank (equidistant between the head of the fibula and the lateral malleolus) of the dominant and non-dominant limbs to identify femurs and tibias. The clusters were fixed through inextensible bands secured with Velcro straps to limit skin motion artifacts during walking. Two additional markers were placed bilaterally on the heel and on the 5 th metatarsal head to identify the gait cycle phases [9].  
Figure 1: Representation of study design.  
Raw marker data were filtered using a fourth-order low-pass Butterworth filter (cut-off 4 Hz). Lower limb clusters were used to define thighs and shanks as rigid bodies, and the movement of the shank was normalized with respect to the thigh in order to compute their mutual positions at each timeframe as a composition of a rotation and translation around a fixed axis (HA) [25; 26]. HAs were computed every 10\({}^{\circ}\) of knee motion along the sagittal plane, and their dispersion was described using MD and MA parameters, according to previous studies [3; 6; 26]. Gait cycle was defined as the timeframe between two consecutive heel-strike events, determined when the markers on the heels assumed the minimum value along the vertical axis of the global reference system [27]. In addition, the knee range of motion (RoM) was described through Euler angles and using the XYZ sequence, as recommended by the International Society of Biomechanics [28]. Furthermore, knee motion was divided into four phases based on kinematics along the sagittal plane: (1) flexion from 95% of the previous gait cycle to 10% of the subsequent gait cycle, (2) extension from 10% to 40% of gait cycle, (3) flexion from 40% to 70% of gait cycle, and (4) extension from 70% to 95% of gait cycle [9]. The first and the last five steps were removed to avoid artifacts, 80 consecutive steps were analyzed for each participant, and MD and MA were computed for each phase and described in reference to sagittal, frontal, and transverse planes adopting the methodology described by [PERSON] and co-workers [9]. Finally, the percentage of HAs passing through the sagittal, frontal, and transverse planes during the four gait phases was also reported. Data were analyzed using MATLAB (MathWorks Inc., Natick, MA, USA) for Windows.