Why Perching is Beneficial for People with Desk Jobs and LBP

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A study 1 published last year in the ‘Ergonomics’ Journal decided to see if perching was a good compromise between standing and sitting. The team concluded that certain custom-made seats could help with keeping low back pain and discomfort at bay. 

What was the Context?

Experiencing low back pain (LBP) and discomfort is linked to prolonged static standing and sitting postures. Studies have shown that taking breaks from standing or sitting can help relieve some discomfort. For example, changing postures from standing to sitting (and vice versa), standing on a sloped surface, walking around for a bit, and using a footrest for one leg are credited for temporarily reducing low back discomfort.

With LBP impacting millions of people around the globe, and professional life demanding people to sit at desks, it’s vital to address certain postures for a person’s wellbeing.

When compared, sitting is said to give rise to the most significant restriction on a person’s postural movements. This is because the frequency of M/L (medial/lateral) and A/P (anterior/posterior) shifts are less than half while sitting as opposed to standing or perching. Past data has led to the suggestion that humans might benefit from the option of sit-stand postures or perching. However, according to the current research team, limited empirical data about perching exists.

What was the Goal?

The primary objective of this study dealt with the identification of where lumbopelvic and pelvic angles in perching significantly deviated from standing and sitting.

This study looked at the possible differences between men and women when it came to standing, sitting, and postures that were in between. It also tested whether sitting and standing were different from hybrid postures. The physical demands related to each position was also observed.

What was the Methodology?

This study included 24 participants (who were divided equally into men and women). None of the participants (falling in the range of being 24-27 years old) had a history of severe lower limb injuries or LBP. The team collected kinematics, muscle activation levels, and ground reaction forces to characterize the range of postures existing between standing and sitting.

Furthermore, EMG (Electromyography) data from three muscles (vastus medialis obliquus, thoracic erector spinae, and lumbar erector spinae) was collected.

Each participant was asked to complete 19 trials (each trial being one-minute long). There was a two-minute standing rest between every trial. The seating device was custom-made. In each trial, the participants were asked to perform a standardized reading task being displayed on a computer monitor. During the task, they were to keep their feet flat on the ground while assuming a relaxed posture. Their hands were to rest on their thighs.

Seat Pan Angle Adjustability

Adjustable Tilt Ergonomic Saddle Seat by Dynamic Disc Designs

What were the Results?

According to the results, the direction of seat movement was observed as being consistent across the participants.

As for the sex differences, a greater lumbopelvic flexion, as well as posterior pelvic tilt (at the 90° trunk-thigh angle), was seen in men compared to women. There were no sex differences observed in other postures. 

Men and women had different standing lumbopelvic and pelvic angles from the rest of the trunk-thigh angles. According to collected data, the perching phase was determined by the team to be in the 145 to 175° range for males and in the 160 to 175° range for women.

The participating women showed significant differences in all of the muscles between phases for both trunk extensors, while men showed none.

The ground reaction force was observed to be different in all phases for both men and women in the A/P direction. Vertical and M/L forces increased in all participants as they moved to the standing position from sitting.

What was Concluded?

By considering collected data, the team concluded that the notable differences existing between the standing/sitting phases and perching came down to the level of leg effort required for a person to remain upright.

Currently, there isn’t an ideal seat that can offer the benefits of perching, sitting, and standing. However, future chair designs could focus on providing trunk-thigh angles in the 115 and 170° range to help address posture-related discomfort.

Said chair designs should also consider two key points:

  • The seat’s interface needs to focus on the alignment of the pelvis for improving lumbar angles as well as to offload some of the lower limb demands.
  • If foot support is featured, it should help redirect force from shear to compression for lower limb joints while decreasing the encumbrance from the user and the workstation being used.

Helping people maintain proper postures, especially during desk jobs, can aid in preventing low back pain and discomfort. More research is required to address such a situation effectively.

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