Study puts bums on seats
It is the ultimate in cheeky research that could stop school being a pain in the neck, literally.
According to an Australian researcher, high school students are commonly suffering from neck and back pain and the humble school chair is partly to blame.
As part of his study, Griffith University researcher Neil Tuttle designed a bumograph, a device to measure the shape buttocks make when seated.
Tuttle, from the School of Physiotherapy and Exercise Science, hopes his research will lead to the design of better school chairs.
He says chair design is complicated by the need for students of different ages and sizes to use the same chairs.
Students also have to undertake different tasks, such writing or listening, that involve different postures.
He says the design of a chair to provide the best fit for a school population is not simply a matter of making it fit the average size person from the population.
"If the seat width and seat height of an armchair were made to fit the average dimensions of a population, the chair would be unusable for most of the population," Tuttle writes in the latest issue of the journal Ergonomics.
He says users with shorter than average knee heights would be unable to place their feet on the floor, while those with a wider than average pelvis would be unable to fit between the armrests.
Instead chairs are designed to ensure the "smallest can fit and the largest can reach".
He says research shows the most important factor in overall sitting comfort is posture, with comfort of the seat surface second.
"The contours of the front and back portions of the seat influence sitting posture and the whole of the seat contour affects seat comfort," he says.
"The contour of the seat affects the two most important factors influencing the comfort of the chair."
Importantly, the chair contours can be an aid in stopping students sliding forward on the chair.
In his study Tuttle used the bumograph to measure the shape of the buttocks of 16 students in five different seated positions: typing, sitting up, sitting back, slumped and writing.
The bumograph replaces the seat of the chair with a slab of high-density foam containing a grid of 96 sensors across its surface.
When he analysed the results, he found it was students' gender that affected the seated buttock shape more than weight, height or posture.
Males had a deeper narrower contour, while female students had a broader, flatter shape.
Tuttle says the gender difference in contour is not enough to warrant chairs for different sexes.
But his findings can be used to create a database that will be an aid in chair design.
Tuttle says an immediate solution to back and neck pain in students is for school authorities to buy adjustable chairs.
"Life expectancy of school chairs is about 10 years," he says. "With Australian authorities spending less than A$40 on each chair that equates to less than A$4 a year per student.
"If you spend an extra A$10 per year per student you can have probably the world's best school chair."
Tuttle also warns teachers against urging students to "sit up" or "sit still".
He says teenage boys leaning back in their chairs with their legs outstretched should not be viewed as lazy and having attitude.
Instead it is a combination of a seat that's too small and the loss of flexibility in teenagers' hamstrings as they grow that makes it uncomfortable for them to sit up.
"If you want to change one attitude it's that there is a correct posture," he says, adding that students should be encouraged to wiggle in their seats.