Research Institute

Cornell University

Graduate students with guidance from Dr. Alan Hedge, investigated sitting pressure on CoreChair compared to a high end ergonomic office chair and discovered that CoreChair has more evenly dispersed weight thereby significantly lowering pressure points. This means significantly better comfort for you.

DEA 6510
Ergonomics + Anthropometrics
Professor Alan Hedge

Ethan Arnowitz
Aditi Khattar
Soumyaa Varshni

CoreChair exerts less pressure points thAn a standard ergonomic task chair

stage 1

10 Minutes : Collect anthropometric data

Hip width was collected from each subject before conducting the experiment.

Stage 2 & 3

10 Minutes : Collect pressure map data during typing task

Our overall goal is to analyze the comfort level of the CoreChair. Our first step was to take anthropometric data from each subject, including hip width. We then asked subjects to conduct a typing task in both a standard ergonomics task chair and CoreChair for 5 minutes. During the typing task pressure mapping data was collected.

From the anthropometric data and pressure mapping analysis, we focused on plotting average pressure vs hip width, overall comfort rating, seat contour, and seat width.

We also conducted a study by plotting hip width vs seat width and seat contouring data collected from the post-experiment comfort survey.
Results were derived and design recommendations were made.

Regular Ergonomic Task Chair for CoreChair Comparison

Standard Ergonomic Task Chair

Seat Depth: 17.4” – 19.85’’ Seat Width: 17.5″ – 21.2″ Seat Height: 17.8″ – 22.6″

corechair up close to see highly sculpted seat cushion

CORECHAIR

Seat Depth: 16.7” – 18.3” Seat Width: 19.3” Seat Height: 17.2” – 19.2”


Stage 2 & 3

10 Minutes : Collect pressure map data during typing task

The following pressure map data was collected during a typing task:

Average Pressure
Average pressure during a certain time frame

Pressure Points
Number of pressure points with 80 mmHg or higher

Stage 4

Survey Part 1:

Body Parts

Please rate (on a scale of 1-5) the level of pain that you feel right now in different parts of your body.

Survey Part 2:

Comfort Statements

Please rate your level of agreement (on a scale of 1-9) with the following statements on chair comfort.

Survey Part 3:

Chair Parts

Please rate the comfort of the following part of the CoreChair.

STUDY analysis

Number of Pressure Points on CoreChair vs Standard Ergonomic Chair

  • Number of pressure points with a range between 80 to 200 mmHg (Red Region) were totaled for both the freedom and CoreChair
  • Results indicated that CoreChair has less pressure points then a standard ergonomic chair.

Number of Pressure Points on CoreChair vs Standard Ergonomic Chair

survey part 1: Body Parts

Please rate (on a scale of 1-5) the level of pain that you feel right now in different parts of your body.

The first section included a five point likert scale where subjects were asked to rate the location of pain in different parts of the body. On the likert scale, 1 represented no pain and 5 represented severe pain.

Six parts of the body were identified including: 1) head/neck, 2) shoulders, 3) back, 4) hips/buttock, 5) upper legs, and 6) lower legs.

The average score, on the scale of 1-5, from all questions in this section is 1.2, indicating that the average overall pain in these parts of the body was minimal.

The lowest pain was found in the hips/buttocks and the lower legs, with an average score of 1.1.

The highest pain was found in the head/neck, with an average score of 1.4.

survey part 2: comfort Statements

Please rate your level of agreement (on a scale of 1-9) with the following statements on chair comfort

The second section included nine questions on a nine point likert scale. In this section, subjects were provided statements and asked to rate their level of general comfort from 1-9. 1 corresponded to the highest level of comfort, similarly to section one. The average for all questions in section 2 were 2.69, indicating moderate to extreme comfort.

The three questions with the greatest comfort scores included:

1) I feel numb with a (1.5)
2) I feel pain (1.6)
3) I feel uneven pressure (1.8)

The three questions with the worst comfort score included:

1) Chair is spacious (4.4)
2) Chair looks nice (4.3)
3) Chair feels soft (4.4)

survey part 3: chair Parts

Please rate the comfort of the following part of the CoreChair.

The third section of the survey included questions asking subjects to rate specific elements of the CoreChair. The features asked about include: 1) seat depth, 2) seat width, 3) seat height, 4) seat contour, 5) backrest height, and 6) lumbar support.

These questions were asked on a five point likert scale. On this scale 1 and 5 would represent two extremes, such as too low and too high, and 3 would represent the ideal balance. The average for the first four questions were within .4 of 3, the ideal score.

Average Pressure vs Hip Width

  • Average pressure increases as hip width increases
  • Has a slope of .909
  • Next we analyzed potential parts of CoreChair that were causing this problem, including seat width and seat contouring

Average Pressure vs Overall Comfort Rating

  • Overall Comfort Rating- developed from the questionnaire on a scale of 24-144. A lower score refers to higher comfort levels
  • Slope is .654
  • As the average pressure increases, the level of discomfort increases

seating width rating vs. hip width & Average Pressure

Seat width rating is from a scale of 1 to 5 where 1 is too narrow, 5 is too wide, and 3 represents a perfect seat width.

Both graphs show that the people with different hip widths and average pressures have a similar rating for seat width which is 3, indicating an ideal seat width.

Conclusion: The seat width of CoreChair is preferred by a large range of people, regardless of average pressure or hip width.

seat contour rating vs. hip width and average pressure

Seat contour rating is from a scale of 1 to 5 where 1 is not enough, 5 is too much, and 3 represents perfect.

A perfect score (3) is only given by people with an average pressure between 29-33 mmHg.

A perfect score (3) is only given by people with a hip width between 13.5”-16”, with large variations. This only represents 46.5% of the population.

Conclusion: CoreChair should redesign the seat contour to accommodate people of varying hip widths and average pressure. To accommodate for 95% of the population, the CoreChair should fit hip widths between 11.95” and 15.5.”

Results

Identified Problems and Design Recommendations

1) Pressure mapping analysis indicated that CoreChair exerts less pressure points then a standard ergonomic task chair
2) Survey questions indicate that CoreChair has a good level of comfort, but could be softer, more spacious, and more aesthetically pleasing
3) Comfort decreases as average pressure increases.
4) Higher hip width leads to higher average pressure.
5) The seat width was measured comfortable by users, regardless of hip width.
6) Seat contouring was only comfortable for hip widths between 13.5”-16.” Because of that, the seat contour could be redesigned for a wider range of hip sizes.