How is a seita fitted to the body?

A seita is a carrier frame for backpacking used in Nishiki-cho, Yamaguchi Prefecture, Japan. In this mountainous district, people make their living by agriculture and forestry and carry everything on their backs with seita. In this study, we investigated the relationships between the sizes of a body and the dimensions of a seita. This survey was conducted on 30 subjects (mean +/- SD; 68.1 +/- 9.0 years old) at three mountain villages. We measured some anthropometric sizes and seita dimensions and found that the correlation between height and sum of shoulder-lumbar-nuki distance (back length of a seita) and shoulder strap length is significant. In additional surveys, we took photographs with some markers on iliocristale, trochanterion, and so on, when the subjects carried seita in two load conditions. The photographs indicate that the load-supporting points in 16 of 23 subjects were between the iliocristale and trochanterion (i.e., on the sacrum). It is important to note that nobody showed that point above the iliocristale (i.e., on the lumbar vertebra). These data lead to the conclusion that when people in Nishik-icho carry loads with seita, they support loads not on the lumbar vertebrae but on the sacrum, and that they adjust the perimeter consisting of the back part and shoulder strap of the seita.