The Reactive Four-Square Step Test (rFSST) is designed to measure reactive stepping.
Two cords of 1 cm thickness are placed on the floor forming a cross and four squares.
The patient is instructed to walk across the cords following the directions commanded by the assessor. The assessor is standing behind the patient following his movements and being ready to catch the patient if necessary. When the assessor says “back” the patient must step backwards across the cord. When the assessor says “forward” the patient must step forwards across the cord. When the assessor says “side” the patient must step across the cord to the side where the cord is next to the patient. A new direction is commanded by the assessor as soon as the patients’ both feet have passed the cord and are touching the ground in the subsequent square. The patient is instructed to step as fast as possible, without touching the cords, with the body facing the same direction all the time and without compromising safety.
After practicing 3-5 steps in random direction two trials of changing squares 8 times are completed. The number of seconds is measured for both trails starting when the foot is touching the ground in the first step and ending when the last step is finished both feet in the same square. The eight changes of squares are executed following a continues pattern moving from the outset square to subsequent squares returning to the outset square and repeating in reverse direction until returning to the outset square again. For each trial a different outset square and stepping direction for the first step is given by the rater. The patient can use any preferred stepping strategy completing the task, but with the body facing the same direction and with both feet touching the ground in the square before continuing to the subsequent square.
The faster of the two trials is used for the test score.
(This approach is like the original FSST but with the distinction that all squares can be used as the outset square. Consequently, the patient is unaware of the stepping directions before the actual commands are executed - Making the task reactive. Further, the patient is not allowed to turn and step forward crossing the cord next to or behind the patient – ensuring that stepping strategy is evaluated in all directions).