University of waterloo
Dr. Callaghan’s research compared the posture of individuals sitting in the CoreChair versus a high end ergonomic office chair, as well as a comparison between CoreChair and a properly fitted exercise ball in the recruitment of core stabilizing muscles.
The outcome concluded that CoreChair is just as effective at providing general postural support while being significantly more effective in providing pelvic support and preventing slumping of the pelvis and ascending spine. CoreChair was also determined to be equal to an exercise ball in the ability to recruit core stabilizing muscles thereby showing that the CoreChair is more efficient at introducing desired movement and an exercise opportunity, while providing optimal support.
Research Team:
Jack P. Callaghan PhD, CK, CCPE
The CoreChair is more efficient at introducing desired movement and an exercise opportunity, while providing optimal support.
The subsequent report presents data collected from 16 participants (8 males, 8 females) and compares the physiological responses to the CoreChair and an ergonomic control chair during two hours of simulated office work. Four different office tasks were examined (mouse dominant work, typing, a combination of the two and reading). Other focuses of the study were: insure that the CoreChair meets minimum mechanical stability guidelines; evaluate the stability and seat pan movements during reaching tasks within the primary through tertiary zones; and assess the torso muscle recruitment while undergoing a series of basic seated exercises on the CoreChair compared to a stability ball.
When the CoreChair was used as a standard ergonomic task chair for office work, it always performed at least as well as a leading ergonomic task chair. Postural responses, muscle activity patterns, both the magnitude and time varying measures assessing muscle rest time were similar between the two chairs. Subjective discomfort, rated by each of the 16 participants throughout the prolonged office work did not show any significant differences between the CoreChair and
the control chair. These findings alone support the potential for the CoreChair to function very well as a task chair. In addition to performing to the same standard as an established ergonomic task chair, the CoreChair also had a significant impact on the postures assumed by the participants over the 1 hour of sitting. The control chair exhibited a well-documented trend of postural creep, with lumbar spine flexion and posterior pelvic rotation increasing over time. These two physiologic responses result in a shift away from a neutral lumbar spine posture. In contrast the CoreChair facilitated more neutral spine postures that persisted over the one hour period. The seat pan was easily controlled by the participants and maintained a neutral average position within 1° of level yet they used the dynamic feature encompassing a range of 3-4° of seat pan rotation in all directions.
The CoreChair passed the front and rear stability tests outlined by the American National Standards Institute. While there are currently no lateral tipping stability tests, when the same test criterion were applied to lateral seat pan rotations the CoreChair also exhibited no potential to tip over. In conjunction with the results from the extended reaching tasks performed by all 16 participants, the centre of mass of the seated user was well within the base of support of the chair
and the stability in these tests confirm that the CoreChair does not present any undue risk for lateral tipping when used for typical office related work tasks. The rotation ability of the seat pan accommodated participants reaching and rotated to a maximum of 8° for the maximum distances.
An additional feature of the three-dimensional rotation capability of the CoreChair is that it can be used for light exercises at a workstation. The muscle recruitment for four exercises were compared against a stability ball and in all cases produced comparable or higher levels of muscle activity indicating it performed very well in targeting the torso or core musculature. The adjustable stiffness control for seat pan rotation in the CoreChair provides varying resistance and can be used to accommodate both different usage (office tasks versus exercise) and well as differing demands during seated exercises.
The one potentially negative finding from this investigation was related to seat pan pressures, which were higher in the CoreChair compared to the control chair. This did not impact subject evaluations, and even the exit survey results scored the seat pan as not having uneven pressure. This is an area that could be targeted for improvement and alternative foam densities and materials should be considered.
Subjective evaluation of the CoreChair during an exit questionnaire was very favourable with scores falling in the 70-80 range on a 100 point scale. This positive response coupled with the fact that this study sought to test a wide range of participant sizes (the heights tested represented 99% of the North America male height range and 75% of the female height range) suggests that the CoreChair will be suitable for a large range of the general population.
results
Overall, the results show that the CoreChair can effectively be used as an office task chair and also provides a similar physical demand when performing light exercise when compared against a stability ball. The CoreChair allows participants to perform office tasks in a similar position
with equivalent muscular demand as a leading ergonomics task chair. The CoreChair provided the benefit of more neutral lumbar spine postures and a larger dynamic range over time compared to the control chair. The postural, muscle activity and discomfort scores collectively indicate that the CoreChair can serve as an ergonomic task chair and performs as well as an
industrial leading ergonomics task chair (control chair). The lack of chronic muscle activity, as illustrated by the probabilities of muscles at rest and the gaps analyses also indicate that there is no apparent negative impact on muscle involvement required to maintain posture or control the dynamic seat pan.
As an exercise device the CoreChair provided similar muscular recruitment, but potentially with an added stability/safety feature – two of the exercises were clearly identified as being abdominal and trunk extensor dominant. The Forward-backward pelvic tilt activated the 6 abdominal muscles the highest and the Circular hip rotation activated the 6 trunk extensors to the greatest levels collectively. This clearly makes the case that these are effective exercises to target these two groups. The other two exercises produced lower levels of activity and may serve as exercises that could be used for earlier stages in an exercise progression program.
Additional Key Points
- There was a general positive response to the design of the CoreChair, as indicated by the high positive scores on the exit questionnaire.
- The CoreChair appears to easily accommodate a wide anthropometric range of heights with no atypical gender or height related findings apparent in the data. Further the exit questionnaire had a very high score on fit with 14/15 respondents saying they felt the chair fit properly.
- The beta cushion seems to have introduced much higher pressures than the control/industry standard and the foam properties need to be further investigated. Interestingly the discomfort was no higher for gluteal area and the exit questionnaire indicated low scores for uneven pressures on the seat pan.
- The CoreChair passed the front and rear stability tests as outlined in the American National Standards. When the same loading conditions were applied on the lateral aspect of the CoreChair, the stability of the chair passed the test. The users’ centre of mass during reaching was well within the base of support of the chair, further confirming stability.
- The additional degree of freedom that allows for sideways motion of the chair did not induce any uneven pressures and the average set pan position during prolonged work was within 1? of neutral.