Jaap van Dieën's research focuses on four themes: 1) Balance control: what determines good balance control, how we can assess balance control and fall risk, and how can balance control be improved?;2) Control of trunk posture and movement: how does trunk control change with disorders like low-back pain, and how can changes in trunk control be assessed clinically? 3) Spine mechanics and low-back pain: how can low-back loading be assessed, and how effective are ergonomic interventions in reducing low-back loading? 4) Measurement tools for biomechanical and neurophysiological assessment with a focus on applications outside the lab.