More than 30,000 ankle-foot orthoses (AFOs) are provided annually in the Netherlands to people with muscle restrictions in the lower leg. For optimal daily use, the stiffness of an AFO must match the user's needs and activities. However, current methods of adjusting stiffness are too cumbersome and focus only on walking on flat surfaces, often leading to non-ideal AFOs. This project is developing a stiffness-adjustable AFO, the ADJUST AFO, that allows easy adjustment of stiffness. Waterval: ‘The data collected with this will help develop a toolbox for better, personally tailored AFO prescriptions in orthotic care.’