Fig 1. Marker setup and theoretical approach to calculate subjects’ ventilation.

Fig 1A shows marker placements (white dots) used in the experiments in frontal, lateral and rear view. Fig 1B displays the theoretical approach used to calculate subjects’ chest volume. Surface areas of the thoracic and abdominal portion were calculated separately according to Eq. 1, and Fig 1C shows the calculation of a cylinder using Eq. 2 that closely matched subjects’ chest volume.