Plain English Summary
Background and study aims:
For people who are wheelchair bound, lower back pain and pressure ulcers (wounds caused when area of skin is placed under pressure) are a big concern. The way a person sits in the wheelchair, including the position of the buttocks and weight put on the spine has an important role in the development of these problems. The aim of this study is to investigate the effects of different sitting positions on back angles and skin pressure in order to see if there is a way to reduce the risk of lower back pain and pressure ulcers in wheelchair-bound people.
Who can participate?
Healthy adult male or female volunteers aged between 20 and 65 years.
What does the study involve?
The participants perform of the seven different sitting positions in random order by drawing lots. Each test lasts for 20 minutes, with periodic changes at 5-minute intervals. The participants are asked to stand up and move around for 5 minutes between each test. Over each 20 minute test, participants have the angle of their spine and pressure on their skin measured.
What are the possible benefits and risks of participating?
There are no direct benefits or risks involved with participating in this study.
Where is the study run from?
Applied Biomechanics Laboratory, National University of Tainan (Taiwan)
When is the study starting and how long is it expected to run for?
March 2015 to November 2015
Who is funding the study?
Ministry of Science and Technology (Taiwan)
Who is the main contact?
Professor Kuen-Horng Tsai
Prof Kuen-Horng Tsai
Graduate Institute of Mechatronic System Engineering
National University of Tainan
West Central District
+886 (0)6 260 6123
Biomechanical effects of different dynamic sitting strategies in wheelchair seating
Lumbar-pelvic angle and interface pressure are influenced by different dynamic sitting strategies.
Institutional Review Board of National Cheng Kung University Hospital, 13/03/2015, ref: A-ER-103-375
Single-centre randomised controlled trial
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
No participant information sheet available
Lower back pain and pressure ulcers
The initial settings for the experimental wheelchair forms a 100° angle between the backrest and seat cushion, and a 120° angle between the seat cushion and footrest. The seat cushion is adjusted to allow a gap between the cushion and popliteal fossa. When the participants are seated in the experimental wheelchair, they are asked to rest their upper body against the backrest, relax their arms and place them at their sides, try to keep their thighs parallel to the ground, place their feet firmly on top of the footrest at shoulder width, and look directly ahead. Next, they perform each of the 7 DSSs in random order by drawing lots:
1. Lumbar prominent dynamic sitting (LPDS): The lumbar adjustment module is positioned at L3 of participant, and the air bag provides dynamic adjustment by deflating to 0 cm and inflating to 4 cm at periodic intervals.
2. Back reclined dynamic sitting (BRDS): Upper body contact is maintained with the backrest in the experimental wheelchair, and the backrest tilt mechanism provides dynamic adjustment by tilting backward and forward between 100° and 150° at periodic intervals.
3. Femur upward dynamic sitting (FUDS): The femur adjustment module is positioned at the midpoint of the participant’s femur, and the air bag provides dynamic adjustment by deflating to 0 cm and inflating to 4 cm at periodic intervals.
4. Lumbar prominent with back reclined dynamic sitting (LBDS): This combines the LPDS and BRDS settings.
5. Lumbar prominent with femur upward dynamic sitting (LFDS): This combines the LPDS and FUDS settings.
6. Back reclined with femur upward dynamic sitting (BFDS): This combines the BRDS and FUDS settings.
7. Lumbar prominent with back reclined with femur upward dynamic sitting (LBFDS): This combines the LPDS, BRDS, and FUDS settings.
Each DSS test lasts for 20 minutes, with periodic changes at 5-minute intervals. The participants are asked to stand up and move around for 5 minutes between each DSS test. Data on lumbar-pelvic angle were collected by the ultrasound-based motion analysis system (CMS20S Measuring System; zebris Medical GmbH, Isny im Allgäu, Germany), and the data on interface pressure were collected by the pressure-mapping mats (Body Pressure Measurement System; Tekscan Inc, South Boston, Massachusetts, USA).
Primary outcome measure
Lumbar-pelvic angle is measured using the ultrasound-based motion analysis system over the 20 minutes of each DDS
Secondary outcome measures
Interface pressure is measured using the pressure-mapping mats over the 20 minutes of each DDS
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Age 20-65 years
Target number of participants
Participant exclusion criteria
1. Spinal pathology
2. Musculoskeletal disorder
3. Those who have sought medical treatment for lumbar pain within the previous 6 months
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
National University of Tainan
Applied Biomechanics Laboratory Graduate Institute of Mechatronic System Engineering No. 33, Sec. 2 Shu-Lin St. West Central Dist.
Ministry of Science and Technology, Taiwan
Ministry of Science and Technology of Taiwan, MOST
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Planned publication in a high-impact peer reviewed journal.
IPD Sharing plan:
The datasets generated and/or analysed during the current study during this study will be included in the subsequent results publication.
Intention to publish date
Participant level data
Basic results (scientific)
2016 results in: https://www.ncbi.nlm.nih.gov/pubmed/27938365