The effect of seat tilting on pelvic position, balance control, and compensatory postural muscle use in paraplegic subjects  Yvonne J. Janssen-Potten, MSc, Henk A. Seelen, PhD, Jan Drukker, PhD, Toon Huson, PhD, Maarten R. Drost, PhD  Archives of Physical Medicine and Rehabilitation  Volume 82, Issue 10, Pages 1393-1402 (October 2001) DOI: 10.1053/apmr.2001.25989 Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 1 An overview of the experimental set-up. Archives of Physical Medicine and Rehabilitation 2001 82, 1393-1402DOI: (10.1053/apmr.2001.25989) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 2 An example of the recorded signals in which the initial sitting position (Phi) and the forward-reaching position (Phb), are indicated. Abbreviations: WS, warning signal; ISt, imperative stimulus; RT, reaction time; t1, time of final target button release; MT1, time between final target button release and pressing the start button again; Phi, first 1000ms; Phb, t1 ± 20% of MT1; ES, erector spinae; T, thoracic; L, lumbar; OA, oblique abdominal muscles; SA, serratus anterior; PM, cranial section of the sternocostal head of the pectoralis major; LD, latissimus dorsi; TPA, ascending part of the trapezius. Archives of Physical Medicine and Rehabilitation 2001 82, 1393-1402DOI: (10.1053/apmr.2001.25989) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 3 Defined unit vector system of the pelvis. Lateral and anterior view of the pelvis. Abbreviations: Z, unit vector parallel to the line through both ASIS; X, unit vector perpendicular to Z and its workline crosses the midpoint between both PSIS; Y, unit vector perpendicular to Z and X. Archives of Physical Medicine and Rehabilitation 2001 82, 1393-1402DOI: (10.1053/apmr.2001.25989) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 4 Typical example of marker displacements during forward reaching of individuals with a high SCI, a low SCI, and without SCI seated in the standard chair, displayed from a lateral view. The bold frames indicate the initial sitting position. The frame representing the initial sitting position and the frame indicating the forward-reaching position of the low SCI person are displayed in detail by the figure on the right. The angles alpha and beta indicate an extension of the spine during forward reaching (α < β). Abbreviations: GT, greater trochanter of the femur; LFE, lateral epicondyle of femur. Archives of Physical Medicine and Rehabilitation 2001 82, 1393-1402DOI: (10.1053/apmr.2001.25989) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 5 Differences in mean pelvic tilt between the 2 chair configurations relative to the standard chair. Differences in mean pelvic tilt between both chair configurations in Phi (▩) and in Phb (▩) are represented. These differences are displayed for each subject separately by the figures on the left side and for the whole group by the figures on the right side. Archives of Physical Medicine and Rehabilitation 2001 82, 1393-1402DOI: (10.1053/apmr.2001.25989) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 6 Average COPmax values and the 99% CI of the mean, for all groups in both chair configurations. Archives of Physical Medicine and Rehabilitation 2001 82, 1393-1402DOI: (10.1053/apmr.2001.25989) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 7 Mean rectified electromyographic activity and the 99% CI of the mean, for all groups, in both chair configurations, in the initial sitting position (Phi). Asterisks (*) indicate a statistical significant change in electromyographic activity between the chair with the 10° inclined seat and the standard chair. (□), standard chair; (■), 10° forward inclination of the seat. Archives of Physical Medicine and Rehabilitation 2001 82, 1393-1402DOI: (10.1053/apmr.2001.25989) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig. 8 Mean rectified electromyographic activity and the 99% CI of the mean, for all groups, in both chair configurations, in the forward-reaching position Phb. Asterisks (*) indicate a statistical significant change in electromyographic activity between the chair with the 10°D inclined seat and the standard chair. (□), standard chair; (■), 10° forward inclination of the seat. Archives of Physical Medicine and Rehabilitation 2001 82, 1393-1402DOI: (10.1053/apmr.2001.25989) Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions