10月 29 2008
英语阅读 Why can’t you just sit still?
Marc Abrahams 是双月刊《不可思议的研究》(Annals of Improbable Research)主编和 “搞笑诺贝尔奖”Ig Nobel Prize组织者。他为《卫报》写的专栏就叫”不可思议的研究”(Improbable Research)。今天的专栏介绍了两位巴西研究者如何研究不同坐姿对椅子产生的压力变化。
Why can’t you just sit still?
Marc Abrahams
The Guardian,
Tuesday October 28 2008
Contrary to what you might think, sitting is not a static activity, unless you are dead. In the study Chair Load Analysis During Daily Sitting Activities, Carla Paoliello and Edgar Vladimiro Mantilla Carrasco adopt the perspective of a chair. They quantify the shifting risks your furniture faces when someone sits on it.
Now – right now – is a great moment in the history of furniture, because “the investigation of furniture behaviour itself and its components under a given load is just beginning”.
Paoliello and Mantilla are based at Universidade Federal de Minas Gerais, in Brazil. They published their report in the Forest Products Journal. Sitting, they emphasise, is indeed a “rather dynamic” activity. Here, in their words, is the situation:
“Sitting is a posture in which the weight of the body is transferred to an area supported mainly by the ischial tuberosities and their surrounding soft tissues. In 1979, Panero and Zelnik determined that when sitting, about 75% of the total body weight is supported by only four square inches. This constitutes an exceptionally heavy load, distributed on quite a small area, and, as a result, a very high level of compressive stress is exerted on the areas beneath the buttocks.”
The buttocks, the butt of so many jokes, are the nexus of our discomfort. Varying parts of it become the focus of pressure. And “such pressure”, warns the study, “causes fatigue and discomfort, which result in a change in the sitter’s posture in an attempt to alleviate the condition”. Therefore we fidget.
But look at the chair. For a chair, stressful and strain-filled adventure comes in many forms. People attack it, so to speak, in at least 11 different ways. Paoliello and Mantilla measured the loads upon different parts of a chair when a person does each of the following (the descriptions are the scientists’ own):
Drop suddenly into the anterior of the chair seat without resting the arms.
Drop suddenly into the middle of the chair seat resting the arms.
Raise both legs.
Lean backward until the front feet of the chair are 5cm above the floor.
Straight back the chair slowly and seat straight.
Drop suddenly in the middle of the right armrest.
Raise both legs.
Drop suddenly in the middle of the left armrest.
Raise both legs.
Stand in the middle of the chair seat.
Jump.
For nine of these actions they provide a photograph that shows either a man or a woman, dropping, jumping or whatever on to or from a chair. The man in each case faces the camera. The woman faces away, whether from shyness or from modesty, it is hard to discern.
The chair was instrumented with 11 load-measuring cells, strain gauges and displacement transducers.
The resulting data, the study says, add weight to “the theoretical understanding of sitting problems”.
(Thanks to Shawn Baker for bringing this to my attention.)
• Marc Abrahams is editor of the bimonthly Annals of Improbable Research and organiser of the Ig Nobel prize
