, for the journal of Ergonomics, decided to compare sitting, standing, and perching. The goal was to analyze if hybrid sit-stand postures could prove to be a better compromise between sitting or standing.
Normal human standing and sitting postures are linked to the development of LBP (Low back pain) as well as discomfort when maintained statically for prolonged periods. However, adjustments in posture can help with relieving some discomfort. This can include taking a short break (from standing or sitting), alternating between sitting and standing, using a footrest, and such.
As far as the musculoskeletal aspect is concerned, sitting and standing are quite different from one another. The joints of the lumbar spine can be put close to the end range of flexion. Similarly, standing can lead to positioning the lumbar spine close to its extension. Passive tissue (including the invertebral discs) can be harmed by such stress.
Why Focus on Hybrid Sit-Stand Postures?
Sit-Stand Postures are also known as Perching. They can be defined as a potential alternative to the normal sitting and standing positions for human beings. The aim of the study was to define three distinct postural planes (sitting, standing, and perching) to examine muscle activations as well as ground reaction forces between them. An objective was to see if a sit-stand posture could offer a better alternative to simply sitting or standing.
The research consisted of 24 participants (12 males and 12 females). Each participant completed a total of 19 one-minute-long static trials. This included sitting at 90°, standing at 180°, and sequentially in a 5° trunk-thigh angle increments.
The collected data covered kinematics, muscle activation levels, and ground reaction forces. A 16-bit A/D system was used to collect all three data sets simultaneously.
What were the Results?
The study determined that the perching level was 145–175° for males, with 160–175° being for females. Furthermore, for both biological sexes, the knee extensor activity was observed to be lower in standing compared to the positions of perching or sitting. Take note, the anterior-posterior forces were observed to be the highest in perching (and required approximately 15% of a person’s body-weight).
What was the conclusion?
Particular chair designs can help with sustaining an individual’s perched posture. The said chair design would aim to reduce the lower limb demands (during perching) within a 115–170° trunk-thigh angle for a better human experience.