Foot weight bearing variations in sitting postures with respect to trunk angles and thigh lengths on chair–a new proposed protocol for determination of sitting postures in foot measurement studies

Foot weight bearing variations in sitting postures with respect to trunk angles and thigh lengths on chair–a new proposed protocol for determination of sitting postures in foot measurement studies

Foot weight bearing (FWB) is important in foot-measurement studies. Methods used to estimate the subject’s FWB in standing posture were usually not practicable in that sitting postures, and FWB was then usually assumed in previous studies. This study investigated the FWB variations in sitting postures with respect to trunk angle and thigh length on the chair. Thirty-six subjects (18 males and 18 females) were recruited in this study. A four-factor factorial design was conducted, including gender (male, female), trunk angle (0°, 45°, Max), thigh length on the chair (1/3-, 1/2-, 2/3-thigh length), and foot side (left, right). FWB was calculated as the proportion of the subject’s own body weight for further analyses. The results showed that both trunk angle and thigh length on the chair had significant effects on FWB. As the trunk angle increased, the mean FWB increased, ranging from 6.57% to 21.91%; as the thigh length on chair decreased, the mean FWB increased, ranging from 12.17% to 17.19%. Overall, the mean FWB ranged from 5.53% and 24.89%. The results provided values of FWB variations in nine sitting postures with respect to three trunk angles and three thigh lengths on chair in both feet of the male and the female subjects (also total population). As a general referential protocol in foot measurement studies, these values can be used by researchers as the predetermined FWB of their studies and then to determine the subject’s sitting postures in terms of trunk angle and thigh length accordingly, or vice versa.