Figure 1.
The back support components included the adjustable sacral, lumbar, and thoracic supports. Each component can be adjusted in the y-axis translation, the z-axis translation, and the x-axis rotation. The seat height, the seat depth, and the pedal length can also be adjusted. The current setting is backward adjustable thoracic support.
Figure 2.
Including the slumped (SS), normal (NS), lumbar support (LSS), and backward adjustable thoracic support (BTS) sitting postures.
Figure 3.
The picture shows the experimental setup with experimental wheelchair, ultrasound-based motion analysis system, and miniature ultrasonic modules. The first belt with triple markers TS-LD was situated around the level of the posterior superior iliac spines and the anterior superior iliac spines. The second belt with triple markers TS-LU was placed firmly around the T12 level. The third belt with triple markers TS-CR2 was placed firmly around the T1 level.
Figure 4.
The back attachment placement and angle definition.
The angular values of spinal regions were then defined for the following: pelvic (the first belt (PSISs & ASISs) relative to the horizontal line), lumbar (the second belt (T12) relative to the first belt (PSISs & ASISs)), and thoracic (the third belt (T1) relative to the second belt (T12)).
Figure 5.
The results of spinal curvature measurement.
Comparison of mean pelvic, lumbar, and thoracic angles across 4 sitting postures, which include the slumped (SS), normal (NS), lumbar support (LSS), and backward adjustable thoracic support (BTS) sitting postures. The positive value (+) represents the posterior tilt or kyphosis while the negative value (-) represents the anterior tilt or lordosis. Error bars indicate SD and * indicates p<0.05.
Figure 6.
The results of back muscle activation measurement.
Comparison of mean maximal voluntary isometric contraction (MVIC) of the lumbar multifidus (LM), lumbar erector spinae (LES), iliocostalis lumborum pars thoracis (ICLT), and thoracic erector spinae at T9 (TES) across 4 sitting postures, which include the slumped (SS), normal (NS), lumbar support (LSS), and backward adjustable thoracic support (BTS) sitting postures. Left side indicate -L, Right side -R, Error bars indicate SD, and * indicates p<0.05.