Stool vs. Back App : a study of lumbopelvic posture, discomfort and perceived effort of sitting

Background: Office workers are at substantial risk of developing low back pain (LBP). A dynamic chair called the Back App has been developed and is speculated to improve sitting posture. Objectives: 1) To compare a) lumbopelvic posture and b) whole body discomfort whilst sitting on a stool, a stable back app and an unstable back app during the performance of controlled deskwork. 2) To determine the perceived effort required to maintain a lumbar lordosis at 30% lumbar range of motion (ROM) whilst sitting on a stool vs. a stable back app. Methods: Ten subjects completed a ten-minute typing task, a thirty-second office task and a one-minute trial of maintaining a short lordotic posture whilst sitting on both the stool and back app device. Postural data between L3/S2 spinal levels and subjective ratings of perceived discomfort and effort were collected. Results: A statistically significant increase in lumbopelvic flexion was noted during stool sitting when compared to both stable (p=0.047) and unstable (p=0.018) back app sitting. Both stable and unstable back app sitting induced lumbopelvic postures close to mid-lumbar ROM with no significant difference between the two (p=0.241). Discomfort was low for all sitting exposures with no significant difference between the three (p>0.05). No significant difference in perceived effort was noted between stool and back app sitting (p=0.158). Conclusions: Both stable/unstable back app sitting promote lordotic sitting postures and may be effective alternatives to stool sitting. Future studies should investigate the effect of Back App sitting on posture and discomfort in LBP populations.