Fig 2. Position of the participant during intermittent flexion.

Visual feedback was provided to the participant about the lumbar flexion (α) and trunk inclination (β) with marks for the required position. In the unsupported condition, a thin rope was placed horizontally in front of the participant at the appropriate height to serve as the orientation point during the flexion and in the supported position the rope was replaced by a padded bar on which the participant was leaning during the flexion.