Smart marker

Gait function measurements were obtained through a level walking task. A 10 m long walkway and software for capturing human motion (First Principle, Northern Digital Inc., Canada) were used to capture the participants’ gait alongside position sensors (Optotrak Certus, Northern Digital Inc., Canada) and force platforms (Bertec Ltd, USA). Motion module marker guide (MusculoGraphics, Inc., USA), which is the standard method for motion analysis [30 (link)], was referenced when placing infrared LED markers (Smart marker, Northern Digital Inc., Canada) on the participants’ legs, as shown in Fig. 4. Participants were asked to walk at their most comfortable pace. Software for Interactive Musculoskeletal Modeling (SIMM, Motion Analysis Corp., USA) was used to extract the gait variables for which an ensemble average of three trials was used as the final value. The variables extracted were the spatio-temporal variables, stance, stride, and swing duration and the subdivisions of the gait cycle. All variables were calculated in reference to the left foot heel contact.Fig. 4

Motion capture and analysis system. A Position sensors and walkway, B lower limb marker placement: lateral and anterior view

To capture the transition movement, a 3-D marker-based motion capture system, which is considered the standard method of movement analysis [35 (link)], was used. Infrared light-emitting diodes (Smart marker, Northern Digital Inc., Canada) were placed according to the motion module marker guide (MusculoGraphics, Inc., USA) as shown in Fig. 2.Fig. 2

Placement of infrared light-emitting diodes

A total of three position sensors (Optotrak Certus, Northern Digital Inc., Canada) and four force plates (Bertec Corp., USA) were used to record participants’ movement and ground reaction force. Custom-built wooden staircase, as shown in Fig. 3, was used.Fig. 3

Custom-built wooden staircase used in the present study