Biomechanical effect of sitting postures on sitting load and feet weight in apparently healthy individuals

Background: Controversies exist about the ideal sitting position. Objective: The present study compared sitting load and feet weight in ischial, sacroischial and ischiofemoral support sitting postures. Methods: Apparently healthy individuals who were asymptomatic of low-back pain for at least 6 months were recruited in the present study. Ischial, sacroischial and ischiofemoral support sitting postures were described based on literature. Assessment of sitting weight was carried out with a standard weighing chair, whereas a bathroom weighing scale was used to assess feet weight. Anthropometric variables were assessed following standard procedures. Data were analysed using descriptive and inferential statistics. Statistical significant level was set at P < 0.05. Results: There were 210 participants comprising 113 males and 97 females, aged 17-35 years. Sacroischial sitting weight of 51.86 (6.57) kg was the highest followed by ischiofemoral sitting weight of 49.52 (6.19) kg and ischial sitting weight of 44.87 (5.99) kg; the differences were statistically significant (P = 0.001). Similarly, ischial feet weight was 19.64 (2.49) kg, followed by ischiofemoral feet weight of 15.92 (2.08) kg and sacroischial feet weight of 12.60 (1.90) kg in sitting positions; the differences were statistically significant (P = 0.000). There was a significant correlation between sitting and feet weights in the different sitting postures and each of height, weight, body mass index (BMI) and femoral length (P < 0.05). Conclusion: The ischial sitting position had the least sitting load, whereas the feet bears the least load in sacroischial sitting. The amount of load experienced in sitting, and the corresponding feet weight was influenced by height, weight, BMI and femoral length. It is implied that sitting position with the highest amount of trunk load has the least amount of feet weight and vice versa.