The effect of backrest inclination, lumbar support and thoracic support on erector spinae muscles when lifting.

The effect of backrest inclination, lumbar support and thoracic support on the erector spinae muscle when lifting while sitting has been investigated. It was found that the lowest values of the iEMG of the back muscle were obtained when: (1) the lumbar support was positioned +4 cm forward, the thoracic support inclined to +10 degrees and the backrest inclination at 110 degrees; (2) the lumbar support was positioned +4 cm forward, the thoracic support inclined to +10 degrees and the backrest inclined to 100 degrees; (3) the lumbar support was positioned +1 cm forward, the thoracic support inclined to +10 degrees and the backrest inclination 110 degrees; (4) the backrest was inclined to 100 degrees the thoracic support inclined to 10 degrees and the lumbar support 1 cm forward; (5) the backrest inclination and lumbar support were both increased; (6) the thoracic support and the backrest inclination were both increased.