Schematic representation of the study design. Following baseline measurements (T0), the subject’s will be prescribed an interventional FRO. The stiffness of this FRO will be varied (rigid, stiff and flexible) and the order of FRO stiffness will be block randomised. Accommodation time for each stiffness will last 4–8 weeks, after which effects will be evaluated (T1K1, T1K2, and T1K3). Following these evaluations, an optimal FRO for the subject will be selected. Follow-up measurements (T2Kopt) will be carried out at 12–20 weeks. B=Block; FRO= Floor Reaction Orthosis; K=AFO stiffness; K1, K2, and K3 represent either rigid, stiff or flexible stiffness configurations.