All individuals will be instructed to realize normal gait imagery (NGI) and gait on the line imagery (GLI) modalities in a single experimental session. The order of imagining these two gait modalities was randomized and both modalities consisted of these tasks: rest (non-imagery task), NGI/GLI before and after the real execution of normal gait/tandem gait on the line. The order of the tasks was not randomized.

Individuals are also asked about the ease/difficulty of imagining both NGI/GLI before and after the real execution of gait tasks using a five-point scale.

Each task is measured once for 30 s with respect to sustained attention and possible onset of fatigue.

The initial position, which is identical for all measured tasks, consisted of an upright bipedal stance in front of an unobtrusive white screen with feet at pelvic width, upper limbs held loosely along the body, eyes open and facing forward. During the rest task, non-motor imagery task, participants are instructed to sing the song "Happy Birthday" in their minds.

NGI before the real execution of normal gait and GLI before the real execution of gait on the line are tasks associated with the imagery of normal gait or tandem gait on the line. Participants first observed a 5 m section of the corridor for NGI, or a line located in the middle of the same corridor for GLI.

The last tasks, NGI after the real execution of normal gait and GLI after the real execution of gait on the line, differed from above mentioned tasks in the immediate real experience of normal gait or gait on the line.

Muscle activity [V] will be measured by surface electromyography during all tasks (rest and gait imagery before/after real gait execution) across both gait imagery modalities (normal gait imagery and gait on the line imagery).

Lower body kinematics will be measured by gyroscope [deg/s] during all tasks (rest and gait imagery before/after real gait execution) across both gait imagery modalities (normal gait imagery and gait on the line imagery).

Lower body kinematics will also be measured by accelerometer [g] during all tasks (rest and gait imagery before/after real gait execution) across both gait imagery modalities (normal gait imagery and gait on the line imagery).

Individuals will be asked about ease/difficulty of imagining both normaI gait imagery/gait on the line imagery before and after the real execution of gait tasks using a five-point scale (maximum value - 5 points [easy] to minimum value - 1 point [difficult]).