Figure 1. Measurement setup for trunk flexion isometric strength testing in standing (A), kneeling (B) and sitting (C) body position. A multi-purpose dynamometer enables measurements in sagittal, frontal and transverse planes. The strap across the pelvis (1) and the knee support bar (2) provide good segmental stability. The height, inclination and horizontal position of the seat (3) could be regulated manually according to subjects` morphological characteristics. Lateral bars with force sensors (4) could be moved vertically and fixed at the appropriate height. A rigid rope connects the belt (at mid sternum level) (5) with the force sensor.