Assessment of Changes in the Pressure Distribution While Sitting in an Instrumented Cushion During an Undergraduate Class

Acquiring a sedentary posture to develop diary activities is considered like an usual activity in the professional or the educational field. However, a lot of people do not know that this posture causes a high pressure between the seat and the person, which is associated with problems and pain in the low back. This work presents the analysis of the pressure variation between the chair and the user during an hour of undergraduate class; with the goal to provide quantitative information to strengthen the importance of active pauses during a class. To measure, monitor, and save the pressure levels generated, we developed an electronic system using five force sensors. The tests were carried out in the Universidad Politécnica Salesiana (Cuenca-Ecuador) with 10 undergraduate volunteers during 50 ± 6 min. The registered pressure levels were visualized through a graphic user interface in Matlab. The higher pressures were registered on the ischial tuberosities with an average pressure of 16.31 kPa without a backrest and 8.89 kPa with a backrest. In addition, it was developed a finite elements simulation to estimate the contact pressure levels generated between the ischial tuberosity and the muscle tissue, with a maximum pressure calculated of 1.27 MPa, distributed over a 4.49 cm $$^{2}$$ area. The objective of this study is to measure the pressures generated between the chair and the buttocks and to quantitatively characterize the sedentary posture of undergraduate students.