What is the ideal desk chair? It turns out that is a very hard question to answer and one that we’ve been exploring for over 35 years. For us it has always been a question of ergonomics – that fascinating place where people and their tools interact. In fact, the late Bill Stumpf spent 11 years studying how the human body could sit comfortably, how we interact with not just our chairs but also the work surface and our computers. The result was the Ergon chair which hit stores in 1976 and is still produced.
Today Gretchen Gscheidle, Director of Research for Herman Miller, who helped Bill Stumpf and Jeff Weber develop products including the now iconic Aeron and Embody, continues our research into ergonomics. Gscheidle, who trained as an industrial designer, is a member of the Human Factors and Ergonomics Society and represents Herman Miller on the Office Ergonomics Research Committee. She knows a thing or two about sitting.
Clockwise from top left: Aeron, SAYL, Embody, Mirra
1. How do you choose an ergonomically-correct chair? Should you match the chair to the kind of back problem you may have? There are 3 rules in ergonomics, seating and otherwise:
- fit the user
- fit the task
- allow postural change and movement
The fitting depends on your body – size, shape, proportions. I for one have a long torso, short arms, so I’m extra focused on armrest height.
You must sit in the chair. If you have chronic issues or even temporary discomforts, yes, you’re going to gravitate toward those chairs that deliver the support where you need it. Fitting also requires “tuning” the chair’s adjustments. There’s often an “ah-ha” when you know everything just feels “right.”
There are plenty of pre-conceptions about what that should be. I encourage people to approach seating with an open mind – there are some amazing technologies in seating – and get some expert advice in the process.
Then you also have to take into consideration what tasks you’re going to be doing in the chair. Reclining is healthy for the back in that it offloads the weight of the upper back onto the chair – but you can’t do that if you’re sitting on an exercise ball, as some people choose to at work. Conversely if you’re looking through a microscope or needing to look down at your hands as you’re sorting materials, reclining doesn’t do you much good there.
Finally, you need to keep moving so you don’t want to be locked into one posture the way that, say a race car driver is in a custom-molded seat.
2. You’ve used pressure map technology to help develop better chairs for Herman Miller. Can you tell us how that technology works? We use very thin, pressure-sensitive “blankets”, that aren’t much thicker than a bed sheet. They are draped over the seat or backrest of a chair while connected to a computer and the associated software. When a person sits down on the mat, a pressure pattern appears on screen. It is a dynamic process, so there’s a “movie” that is captured, or you can review individual frames.
The pattern changes depending on who is sitting in the chair, what they’re sitting on, and how they’re sitting. Like on a weather map, the colors in the map indicate intensity. When reading the map, you’re looking for symmetry as well as more intense pressure to be in some places, like under the sitting bones of the pelvis, and less pressure in other places like behind the knee. Beyond that, you’re taking into consideration the sitter, the sitter’s posture and construction of the chair in interpreting where on the scale between “good” and “bad” a particular map falls. It’s why we consider the exercise as much “art” as “science.” Believe it or not, Aeron and SAYL would be fairly indistinguishable in a pressure map.
Above: The image on the far right represents a person sitting in an Aeron or a SAYL chair. The lack of red means weight is distributed evenly across the seat.
3. Tell us about the importance of blood and oxygen when it comes to sitting. There has been a bit of talk lately about standing desks but that must have ergonomic hazards as well? Well, cells need oxygen, transported by blood, to burn energy – metabolize – and stay healthy. Blood also carries carbon dioxide – waste from the body’s burned energy – out of the cells. The effectiveness of this process is facilitated through tissue perfusion, a measure of the exchange of oxygen and carbon dioxide within the body’s tissues. It’s the basis for keeping individual cells and ultimately human beings alive.
Compressed soft tissue reduces blood flow and thus tissue perfusion. Over time static loads on soft tissues trigger the body’s natural defense mechanism. The discomfort that is experienced results in fidgeting or macro movements like the feeling of, “I’ve got to get up.” Both extremes allow blood to circulate again and health to be restored. In individuals with compromised nervous systems that discomfort is not felt and therefore the body is very vulnerable to serious issues because the cells die from a lack of oxygen.
As for standing desks, it is a function of conditioning – if you aren’t accustomed to being on your feet, you’re going to lean and offload your body weight elsewhere. And, it’s also a question again of tasks. Can you stand for the tasks that you’re needing to accomplish? Sit-to-stand desks are a nice solution because at times you can stand, others you can sit – forward, upright, or reclined – assuming your chair has that range of accommodation.
4. What do you sit in when you’re working? It depends. I’m a mobile worker, so it depends on where I’m at, and what’s waiting for me there. In my home office, I sit in a prototype Embody chair.
Originally published at Lifework by Cerentha Harris