1. Why Seated Fatigue Deserves a Fresh Look
Office workers spend an average of more than eight hours seated every day. Since the pandemic, remote and hybrid work have shifted the burden of setting up a workspace onto the individual. And yet some people stay noticeably less fatigued than others, even after the same hours at a desk. Is it the chair? The desk? Today we review three authoritative sources that point to a different answer.
2. What the Lumbar Disc Actually Carries — Nachemson's Classic Work
Swedish orthopedic surgeon Dr. Alf Nachemson published a landmark series of studies in the 1960s–70s that directly measured internal pressure inside lumbar intervertebral discs during different postures. His 1976 summary in Spine is still a foundational reference for office furniture design[^1]. One consistent finding is that a forward-leaning seated posture places substantially higher load on the lumbar disc than standing. When the feet don't find a stable resting point and the pelvis tips backward, that load grows further.
3. The Office Standard — ISO 9241-5 on Chairs and Footrests
International standard ISO 9241-5 defines ergonomic requirements for VDT (visual display terminal) work, including chair, desk, and foot support[^2]. Chair height should allow the knees to rest near 90 degrees, and for users whose feet cannot rest flat on the floor, an adjustable footrest is recommended. Cornell University's Ergonomics Web (CUErgo) publishes guidance along the same lines[^3]. Stable foot contact is framed not as an optional extra, but as a baseline condition for seated work.
4. Body Diversity in the Real World — Size Korea and KOSHA
Most standard office chairs are designed around an average body. Actual human dimensions are far more varied. Size Korea, the nation-wide anthropometric survey, shows that adult leg length can differ by more than 10 cm between individuals[^4]. KOSHA (Korea Occupational Safety and Health Agency) emphasizes adjustable support tools in its office environment guidance to accommodate this diversity[^5]. "Standard size" means built for the average — and therefore not a perfect fit for most individuals.
5. What the Three Sources Agree On
Nachemson's data says spinal load changes dramatically with seated posture. ISO 9241-5 declares stable foot contact a baseline requirement. Size Korea and KOSHA confirm that one size does not fit everyone. Taken together, the message is simple: foot support is not a luxury add-on to seated work — it is a baseline condition, and meeting it requires a support surface that can be adjusted to the individual.
6. Behavioral Design — Design the Posture Instead of Demanding It
ROUMO doesn't tell users to "sit up straight." Instead, we change the environment so that a good posture maintains itself. When the legs find something to rest on, the pelvis settles; when the pelvis settles, the lower back follows naturally. LC99 adjusts height between 5 and 19 cm and offers 81 angle combinations (9 steps × 9 steps, front and back). Different bodies find their own geometry — exactly what the research calls for, delivered in a form you can put under your desk today.
7. FAQ
Q. Is a footrest really necessary?
A. Not for everyone. If your chair height already matches your leg length well, you can do without. But because most standard office chairs are designed around an average body, a footrest is how many people bring their setup up to baseline.
Q. How is a height-only footrest different from one with angle adjustment?
A. A fixed angle locks the calves and ankles into one posture. Adjustable angle lets you compensate for small differences in seat depth and chair height, which translates into meaningfully less fatigue over long sessions.
Q. Can I benefit without replacing my chair or desk?
A. Yes. A footrest simply adds a surface for your feet, so you keep your current setup and upgrade the one thing that's often missing — a supportive place for the legs to rest.
Related Posts
- Why the Soles Are Called the "Second Brain" — The Hidden Physics of Good Posture
- Seated Lumbar Load, ISO Standards, and Body Diversity
- Explore LC99
📚 References
[^1]: Nachemson, A. (1976). The lumbar spine: an orthopaedic challenge. Spine. PubMed 1265196. https://pubmed.ncbi.nlm.nih.gov/1265196/
[^2]: ISO 9241-5:1998 Ergonomic requirements for office work with visual display terminals (VDTs) — Part 5: Workstation layout and postural requirements. https://www.iso.org/standard/16877.html
[^3]: Cornell University Ergonomics Web (CUErgo). https://ergo.human.cornell.edu/
[^4]: Size Korea National Anthropometric Survey. Korean Agency for Technology and Standards. https://sizekorea.kr/
[^5]: Korea Occupational Safety and Health Agency (KOSHA), Office Environment Guidance. https://www.kosha.or.kr/