Return to the review of the research on Balans seating
Yes, we need to move but all movements are not the same. Review of the literature relevant to the Balans
Comments by designer Peter Opsvik.
Abstracts of studies cited in our review of the research, listed in order it is reviewed.
Unpublished or hard to find articles can be downloaded on this page as pdfs.
Courtesy of VarierUSA and Varier International.
Over the last two decades, our focus has gradually shifted from identifying the best single sitting posture towards a more dynamic view of sitting and movement.
This research review aims to revisit what we know about sitting postures and movements and the associated implications for Balans sitting and seating.
This page lists the abstracts that specifically relate to Balans chairs, it links to Medline and other sources for ordering the articles, and it makes papers that are not readily available
Kneeling chairs and posture
Balans chairs and lumbar lordosis
R. Lueder summary: Although the research findings varied, the majority demonstrated improvements in lumbar lordosis — that is, a shift towards more neutral postures - when sitting on the Balans chair.
Further, the flexed knee position may work in concert with the increased thigh-torso angle in promoting neutral postures. The Balans chairs tested in these studies lacked the backrests currently available in some models of the Balans chair.
Adams, W.P.; Stentz, T.L.; Stonecipher, B.L.; Hallbeck, M.S. (1990) Comparison of spinal profiles while standing, supine, prone, and seated in four chair types: A pilot study. Human Factors and Ergonomics Society Annual Meeting Proceedings. 34(679-683. link
Abstract: A 3-dimensional digitizer was used to evaluate the spinal profiles of 16 subjects. These subjects (8 female, 8 male) are from 4 age ranges: 12-14,20-22,40-42, and 60-62 years of age. Each subject was measured in 7 different body positions to include: standing, supine, prone, and seated on one of 4 different chair styles. The 4 chairs were a metal folding chair, a stackable plastic molded chair, a 5-caster padded "secretarial" chair, and an ergonomic kneeling "posture" chair similar to a Balans chair. The measured spinal profiles were separated into 4 spinal angles (measured with respect to a vertically projected line), the cervical, thoracic, lumbar, and sacral angles. Each spinal angle was the dependent variable for an ANaYA analysis. The independent variables were posture, age, gender, and subject. The ANOVA analysis showed that the main effect of posture was significant for the thoracic, lumbar, and sacral angles. Post hoc testing demonstrated that the supine thoracic angle differed significantly from the other 6 body postures, which were grouped together. The mean lumbar angle had two groupings. One group included the standing, prone, and supine postures, while the other group was comprised of the seated postures. The sacral angle for the standing, prone, and supine postures did not differ significantly, but were different from the seated postures. The sacral angle for the ergonomic posture chair was significantly different from the other chairs, with the magnitude of its mean angle between the standing, prone, and supine group, and the group of other seated postures.
Bendix, A.; Jensen, C.; Bendix, T. (1988) Posture, acceptability and energy consumption on a tiltable and a knee-support chair. Clinical Biomechanics. 3(2), 66-73. ScienceDirect link
Abstract: Sitting postures on a knee-support (Balans®) chair and a tiltable chair were investigated with 12 healthy subjects during office work and simulated assembly work. After at least 3 weeks' adaptation to each chair, the subjects were investigated for 1 hour on each chair in stratified sequence. Postures were evaluated by means of a statometric method. Spinal load was further estimated by measuring stature shrinkage over each sitting period. Energy consumption was roughly assessed by pulse measurements. Finally, subjective acceptability was rated by a 5-point scale. Posture effects of the Balans® chair, taken in relation to the tiltable chair, were primarily a forward tilt of the pelvis and a change toward lumbar lordosis. Secondly, the trunk was vertical compared to the slightly backward-inclined position in the tiltable chair. The head was most vertical in the Balans® chair. No effect on spinal shrinkage or pulse was observed. The subjective rating seemed to favour the tiltable chair if used over longer periods. However, the Balans® chair may be a good alternative for some seated periods and special tasks.
Bennett, D.L.; Gillis, D.K.; Portney, L.G.; Romanow, M.; Sanchez, A.S. (1989) Comparison of integrated electromyographic activity and lumbar curvature during standing and during sitting in three chairs. Physical Ther. 69(11), 902-913. Medline link
Abstract: The purposes of this study were to monitor the integrated electromyographic activity of the erector spinae (ES) muscles and to measure lumbar curvature (LC) during static and dynamic postures in three chairs--a Balans Multi-Chair (BC), and office chair (OC), and a straight-back chair (SBC)--and during standing. Integrated electromyographic data were recorded in relaxed and erect postures at L2 and L5 in 20 volunteers. Lumbar curvature was measured with a flexible ruler. Analyses of variance for repeated measures (p = .05) and paired t tests were used to compare the IEMG and LC measurements. During relaxed postures, there was more IEMG activity and greater LC in standing than in the OC or the SBC. During erect postures, there was more IEMG activity in standing than in the OC and no difference in LC between chairs. The IEMG activity at L5 was greatest on the left side across chairs. In typing and writing, significant differences in IEMG activity were found between sides, but not between chairs. The LC was greater in the BC than in the SBC in relaxed sitting, typing, and writing. The pattern of IEMG activity is not similar to corresponding LC measurements. Care and prevention of low back injury is a critical focus in physical therapy. The BC could contribute to treatment. Further research is needed to support its use in back care programs.
Bettany-Saltikov, J.; Warren, J.; Jobson, M. (2008) Ergonomically designed kneeling chairs are they worth it? : Comparison of sagittal lumbar curvature in two different seating postures. Stud Health Technol Inform. 140(103-106. Medline link
General agreement among researchers suggests that poor seating posture may predispose individuals to developing low back pain. A variety of methods such as ergonomically designed chairs have been developed to assist people to maintain good posture and preserve the 'natural' lumbar curve. The aim of this study was to compare lumbar curvature on an ergonomically designed kneeling chair (EKC) with that on a standard computer chair (SCC), with reference to the standing lumbar curvature. The study used a repeated measures, within-subjects design. A convenience sample of twenty participants was recruited aged 18-35 (9 male and 11 female). Lumbar curvature was measured using the 'Middlesbrough Integrated Assessment System' (MIDAS) postural assessment tool in three different postures; sitting on a SCC, sitting on an EKC set at +20 degrees inclination and standing as the reference measurement. Results were analysed by a repeated measures oneway ANOVA (1 factor) with 3 levels followed by the Bonferroni post hoc test. The results showed a statistically significant difference between standing lumbar curvature and lumbar curvature produced by both of the chairs (p < 0.05). There was also a statistically significant difference between the two seated positions (p < 0.05). This study suggests that ergonomically designed kneeling chairs set at +20 degrees inclination do maintain standing lumbar curvature to a greater extent than sitting on a standard computer chair with an overall mean difference of 7.633 degrees . Further research with a greater number of subjects and on different chair designs is warranted.
Bishu, R.R.; Hallbeck, M.S.; Riley, M.W.; Stentz, T.L. (1991) Seating comfort and its relationship to spinal profile: A pilot study. International Journal of Industrial Ergonomics. 8(1), 89-101. ScienceDirect link
Abstract: Chair comfort is a subjective rating, comprising many factors which can be conceptually modelled. It was postulated that the overall comfort perceived by chair users is a function of the relative discomfort in various regions of the body and that the discomfort perceived in the lumbar region is a function of the spinal curvature. The results of two experiments are reported here. In the first experiment, five typical office chairs were evaluated in a field experiment using five subjects. The evaluation procedure used a general comfort rating scale, a body part discomfort rating scale, and a chair feature evaluation checklist. The results showed the body part discomfort ratings of the back regions to be critical in chair comfort. In the second experiment, three chairs were evaluated employing six subjects. The spinal posture of each subject was measured with a METRECOM® digitizer while standing and seated in each chair type. The results indicate that the backrest curvature, and the thigh-trunk angle (included angle between the seat pan and the back rest) are critical for the overall chair comfort. The implications for the chair designer are discussed.
Bridger, R.S.; Von Eisenhart-Rothe, C.; Henneberg, M. (1989a) Effects of seat slope and hip flexion on spinal angles in sitting. Human Factors: The Journal of the Human Factors and Ergonomics Society. 31, 679-688. link
Abstract: Lumbar and thoracic spinal angles of 25 male and 25 female subjects were measured in four sitting postures, with standing spinal angles used as reference. Subjects sat with either 90 deg or 65 deg of hip flexion on either flat or forward-sloping seats. Lumbar kyphosis was greatest when the flat seat/90-deg posture was adopted and least when the sloping seat/65-deg posture was adopted. The opposite was observed for the thoracic angles, and intermediate results were observed for the other two sitting postures. No statistically significant interactions were observed among seat slope, hip flexion, and subject sex. The findings are discussed with reference to the anatomy of sitting and factors influencing pelvic tilt and the implications for the ergonomic design of chairs.
Bridger, R.S.; Wilkinson, D.; Van Houweninge, T. (1989b) Hip joint mobility and spinal angles in standing and in different sitting postures. Human Factors. 31(2), 229-241. Medline link
Abstract: The spinal angles of 25 female subjects were measured in standing and in four different sitting postures with various trunk-thigh angles. Additionally, measurements of hip and lumbar mobility were made in an attempt to relate mobility to spinal curvature in the different sitting postures. Lumbar curvature was observed to decrease as the trunk-thigh angle decreased across the different sitting postures, and reduction in curvature was associated with hip mobility. An exploratory analysis of interrelationships among hip mobility, spinal mobility, and spinal curvature was also carried out. A significant correlation between lumbar and thoracic angular deviations in standing and hip flexion/extension range was obtained. The findings are discussed with reference to theories of sitting posture and the influence of hip joint mobility on postural adaptations to furniture. Further investigations, including studies of male subjects, are indicated.
Brunswic, M. (1984a) Ergonomics of seat design. Physiotherapy. 70(2), 40-43. Medline link
Abstract: The implications for seat design of unsupported sitting are discussed in the light of two experiments. They show the importance of considering seat design as an integral part of task and workspace design rather than in isolation. The problem of unsupported sitting are analyzed and seating solutions reviewed. Two experiments illustrate the effects of seat design and task on spinal posture. Implications for seat design are drawn from the results of these studies.
Brunswic, M., (1984b) Seat design in unsupported sitting. Proceedings of the 1984 Intl. Conference on Occupational Ergonomics, Toronto, 294-298. Click to download original article (800 kb pdf; hard to find elsewhere).
Abstract: The problem of unsupported sitting are analyzed and seating solutions reviewed. Two experiments illustrate the effects of seat design and task on spinal posture. Implications for seat design are drawn from the results of these studies.
Ericson, M.O.; Goldie, I. (1989) Spinal shrinkage with three different types of chair whilst performing video display unit work. International Journal of Industrial Ergonomics. 3(3), 177-183. ScienceDirect link
Abstract: The aim of the study was to investigate the magnitude of spinal shrinkage during video display unit (VDU) work when subjects were sitting on chairs with different design with forward-sloping seats with or without backrest, armrest or knee support and when using a conventional chair with horizontal seat. Three different chairs were investigated: A "Conventional chair" with horizontal seat, B "Ullman chair" with front half of seat sloping forward and back half horizontal, and C "Balans chair" with forward-sloping seat plus knee support. Eight healthy subjects used to professional VDU work volunteered to participate in this field study, which was performed at their own workplaces. The median shrinkage after a three-hour period was 1.3, 1.8 and 3.1 mm for chairs A, B and C, respectively. All subjects shrank more (p < 0.05) when sitting on the chair with knee support (C) than when sitting on the conventional chair. There was no statistically significant difference in shrinkage between chairs A and B, or between chairs B and C.
Frey, J.K.; Tecklin, J.S. (1986) Comparison of lumbar curves when sitting on the Westnofa Balans multi-chair, sitting on a conventional chair, and standing. Phys Ther. 66(9), 1365-1369. Medline link
Abstract: The purpose of this study was to determine whether the Balans Multi-Chair (BMC) approximates the amount of standing lumbar curve better than a standard conventional chair (SCC) in seated subjects writing at a desk. The length of the curve from L1 to S2 was measured with a flexible ruler in 44 healthy subjects who were standing and sitting on both an SCC and a BMC. A one-way analysis of variance for repeated measures and the Student-Newman-Keuls test were used to examine the differences in the curves created in the three positions. The frequency of subjects sitting in lumbar flexion was compared using a chi-square test with those not in flexion. Lumbar curves measured in the three positions were significantly different (p less than .01). The BMC approximated the standing lumbar curve in seated subjects writing at a desk to a greater degree than the SCC. In addition, the BMC produced lumbar flexion less frequently (chi 2 = 4.33, p less than .05) than did the SCC. These data suggest that the BMC may be an appropriate adjunct in client care when minimal lumbar flexion or lumbar extension is indicated.Abstract: The purpose of this study was to determine whether the Balans Multi-Chair (BMC) approximates the amount of standing lumbar curve better than a standard conventional chair (SCC) in seated subjects writing at a desk. The length of the curve from L1 to S2 was measured with a flexible ruler in 44 healthy subjects who were standing and sitting on both an SCC and a BMC. A one-way analysis of variance for repeated measures and the Student-Newman-Keuls test were used to examine the differences in the curves created in the three positions. The frequency of subjects sitting in lumbar flexion was compared using a chi-square test with those not in flexion. Lumbar curves measured in the three positions were significantly different (p less than .01). The BMC approximated the standing lumbar curve in seated subjects writing at a desk to a greater degree than the SCC. In addition, the BMC produced lumbar flexion less frequently (chi 2 = 4.33, p less than .05) than did the SCC. These data suggest that the BMC may be an appropriate adjunct in client care when minimal lumbar flexion or lumbar extension is indicated.
Link, C.S.; Nicholson, G.G.; Shaddeau, S.A.; Birch, R.; Gossman, M.R. (1990) Lumbar curvature in standing and sitting in two types of chairs: Relationship of hamstring and hip flexor muscle length. Phys Ther. 70(10), 611-618. Medline link
Abstract: A purpose of this study was to determine the difference in the lumbar curves of subjects while they stood compared with while they sat in two chairs with different seat angles--the Balans Multi-Chair (BMC) and a standard conventional chair (SCC). An additional purpose was to determine the relationship between lumbar curvature and 1) anthropometric factors and hamstring and hip flexor muscle length during standing and during sitting in the two chairs and 2) amount of time spent sitting. Sixty-one men between 20 and 30 years of age served as subjects. Lumbar curve measurements were taken with a flexible ruler with the subjects first standing and then sitting in the two chairs. Hamstring and hip flexor muscle lengths were indicated by range-of-motion measurements taken with a gravity goniometer. Age, number of hours spent sitting per day, upper body length, and right leg length also were recorded. Subjects had significantly more lumbar extension when they sat in the BMC than when they sat in the SCC. Hip flexor length was the only factor that appeared to relate significantly to the difference between the standing lumbar curve and the lumbar curves in the BMC and the SCC.
Balans chairs and Electromyography (EMGs)
R. Lueder summary: A number of EMG studies have found that muscle loads increased when sitting on the Balans chair. None of these studies compared sitting on Balans chairs that provide back support with conventional seating. Further, these studies have been closely controlled and lack the real world settings that today's office workers operate in. Yet EMG research is controversial and often lead to confounded conclusions (Smoliga et al, 2010; Ankrum 2000a; Ankrum 2000b). The goal is not to minimize EMGs – after all, exercise is beneficial to health - but rather to avoid excessive muscle loads that exceeds the users’ ability to recover. Further, Ankrum points out that much of the research has confused statistical significance with meaningful differences.
See Bennett et al (1989), above. Medline link
R.L. comments on this study on the topic: Bennett et al (1989) measured muscle activity/ EMGs noted that, given that lumbar lordosis improved in the Balans chair, the findings that Balans sitting involved higher EMGs than sitting in conventional chairs "suggests that EMG activity is not a good indicator of changes in lumbar posture". That is, changes in EMG activity are unable to evaluate the benefits associated with improvements in lumbar lordosis.
Shenoy, S.; Aruin, A.S. (2007) Effect of chair design on feed-forward postural control in sitting. Motor Control. 11(4), 309-321. Medline link
Abstract: The objective of this study was to determine if a forward-tilted seat and the resultant semi-kneeling body position associated with sitting on the Balans Multi Chair (BMC) affect postural control in sitting. Nine healthy subjects were seated on either the BMC or a regular (REG) chair with their arms extended. They were instructed to induce self-initiated body perturbations in four different directions by exerting brief pulses of force against a stationary frame positioned in front of them. Electromyographic (EMG) activities of trunk and leg muscles were recorded before and during the perturbations. The results show that sitting on both types of chairs was associated with anticipatory activation of trunk and upper leg muscles. In contrast, anticipatory activation of distal muscles was observed while sitting only on the REG chair and was absent while sitting on the BMC. The outcome of the study suggests that although the forward-tilting seat and semi-kneeling body position might help in preserving a normal lordosis, it is not associated with anticipatory activation of lower leg muscles, which might reduce the ability of an individual to counteract self-initiated body perturbations. These findings stress the important role of chair designs in the control of sitting posture.
R.Lueder comments on this study on the topic: Shenoy and Aruin (2007) compared the EMGs associated with sitting on a forward-tilted seat and the Balans Multi Chair without back support. Sitting on both the Balans and standard forward-tilting seat pan resulted in anticipatory activation of trunk and upper leg muscles in some postures. These findings suggest that although the forward-tilting seat and semi-kneeling body position might help in preserving a normal lordosis, it is not associated with anticipatory activation of lower leg muscles, which might reduce the ability of an individual to counteract muscle forces associated with these postures.
Lander, C.; Korbon, G.A.; Degood, D.E.; Rowlingson, J.C. (1987) The balans chair and its semi-kneeling position: An ergonomic comparison with the conventional sitting position. Spine (Phila Pa 1976). 12(3), 269-272. Medline link
Abstract: Recently, the Balans chair has been introduced with claims that, because of its semi-kneeling position, individuals will experience decreased low-back pain (LBP) as well as improvement in circulation. This study investigated the validity of these claims. Twenty healthy subjects were randomly assigned to one of two groups. Group 1 subjects sat in the Balans chair for a 30-minute study period and then sat in a conventional office chair for an additional 30-minute period. Group 2 subjects were studied in the reverse seating order. Parameters studied were cervical and lumbar paraspinous surface EMG, and pedal cutaneous blood flow measured by laser-Doppler flowimetry. In addition, a questionnaire comparing the comfort of the two chairs was completed at the end of the study session. Comfort ratings showed an overall preference for the conventional chair. Increased cervical (P = .004) and lumbar muscle EMG measurements were noted after sitting in the Balans chair. Pedal cutaneous blood flow was increased by 15% in the Balans chair (P = .001). The data do not support the manufacturer's claim that the Balans chair is likely to decrease complaints of LBP.
R.L. comments on this study on the topic: Lander et al (1987) found that EMG levels were higher after sitting on a Balans chair without back support, which presumably related to the work configuration and lack of backrest F. Cram and Vinitzky (1995) emphasized the importance of providing pelvic and back support with alternative seating.
Balans and loads on the knees
R. Lueder summary: Some studies point to a lack of any evidence of negative loading on the knees when sitting on the Balans. Two very early studies suggested that some users reported discomfort at the knees when sitting on Balans chairs. Both of these were poorly controlled informal studies that lacked commonly recognized approaches for controlling for confounding factors. These may also have reflected early versions of the chair, since this writer has not found any more recent reports of discomfort at the knees in the last two decades.
Stranden, E. (2000) Dynamic leg volume changes when sitting in a locked and free floating tilt office chair. Ergonomics. 43(3), 421-433. Medline link
Abstract: It is well established that prolonged sitting may lead to swelling of the lower extremities. However, activation of the vein pump system by repeated walking breaks or dynamic tiltable foot-rests have been shown to reduce foot and leg oedema. Some office chairs incorporate tilt mechanisms facilitating movements of the body from the feet up. The present study was undertaken to establish whether a beneficial effect on the transcapillary fluid balance of the legs by enabling such mechanisms could be documented. An office chair where the tilt mechanism could be locked or open was used for the study. The seat position and seat activity level was recorded by a transducer system developed for the study. Calf volume and calf muscle pump activity was detected by mercury strain gauge plethysmography. In the locked position there was a steady increase in volume of mean = 1.2% (range = 0.8-1.8%) for all participants in the 30-min study period. On the other hand, for all participants there was a decrease in calf volume (mean = 0.7%, range = 0.1-1.2%, p = 0.008) when the tilt mechanism was open (30-min period), irrespective of what study period came first. The study showed that upward seat deflection was not associated with concomitant venous obstruction, since such obstruction was detected in less than 2% of the time period with more than 50% of maximal upward deflection. A locked seat mechanism does not prevent activation of the vein pump mechanism, but the study indicates that office chairs that permit variation in seat angle per se stimulate movements of the leg. This, in turn, activates vein pumps and counteracts local oedema formation in seated working postures.
R.L. comments on this study on the topic: Stranden (2000) pointed to the absence of evidence linking sitting on the Balans seat with loads on the knees, and described a prior unpublished study (Stranden, 1981) that also found no such evidence.
On this aspect, he wrote...
“Furthermore, the flexion of the knee joint during upward seat deflection does not represent a likely cause for venous compression. This is evident from earlier studies on `Balans' chairs, where venous pressure recordings at very much larger flexion did not indicate any venous obstruction at all (Stranden 1981). The most extreme sitting posture was applied at `Balans Skulptur', where flexion was about 160 ± 1708; still with no venous obstruction affecting venous pressure profiles.”
R. Lueder also reported in her review of the research that she also reviewed partial reports from an in-house research study performed over nine months by physiotherapists at the Hospital of Robslend, Norway. They reported improvements in back pain but also acknowledged a potential for knee discomfort — which they said could be avoided through simple design changes.
Drury, C.G.; Francher, M. (1985) Evaluation of a forward-sloping chair. Applied Ergononomics. 16(1), 41-47. Medline link
A methodology of chair evaluation developed earlier was applied to a novel, forward-sloping chair. Two groups of six subjects each were trained to use the chair and then given an evaluation session of [Formula: see text] . The chair elicited mixed responses, with complaints of leg discomfort from terminal users and of entry and egress from typists. Overall, the chair was no better than conventional chairs and could be worse than well-designed conventional office chairs.
R.L. comments on this study on the topic: Drury and Francher (1985) performed a small pilot study of 12 subjects sitting in Balans and conventional chars for 2½ hours. Balans chair users chair reported higher rates of body part discomforts at the knees and (to a lesser extent). Even so, the authors noted, “a minority of subjects preferred this [Balans] chair to their own”.
Grandjean's writings on knee loads
Grandjean, E. (1976) Ergonomics of the Home. London: Taylor and Francis. Amazon link to the book
Krueger H (1984). Zur Ergonomie von Balans-Sitzelementen im Hinblick auf ihre Verwendbarkeit als regulare Arbeitsstuhle. Report 8092. Zurich: Department of Ergonomics, Swiss Federal Institute of Technology.
--» Download original unpublished paper as pdf, courtesy of Dr. Krueger (4.3 MB pdf; not otherwise available)
Hermenau, D.C. (1999) Seating. Edited by Jacobs, K. Ergonomics for therapists. Woburn, MA: Butterworth-Heinemann. Citation on Page 203. Chapter 10, 219-237. Amazon link
Hermenau, D.C. (1995) Seating. Edited by Jacobs, K. Ergonomics for therapists. Woburn, MA: Butterworth-Heinemann. Chapter 9. Amazon link
Several of Grandjean’s editions of “Fitting the task to the man” (e.g., 1988 – see also Kroemer and Grandjean (1997)) reference an unpublished in-house report from the Swiss Federal Institute written in German by Krueger (1984 - see below), noting in each case.
Each time, Grandjean wrote...
“Krueger (1984) tested four models and found that the load on knees and lower legs is too high and sitting becomes painful after a while. (Some subjects even refused to sit longer than 2 h).”
R.L. comments on this study on the topic: Some others followed suit, describing this study — and one cannot help but wonder if it might have been taken as a secondary source from Grandjean without referencing it as such or reading the original material. Notably, Hermanau (1995, 1999) writes...
“Studies by Krueger (1984), however, found that the load on the knees and lower legs is too great and sitting becomes painful.”
Yet The Swiss Federal Institute indicated that they had no record of having sponsored such an unpublished German report and that it apparently not available directly from their Institute, leaving one to wonder whether recent articles that cite this report might be making inferences from secondary references to text that they have not actually read.
Both the translated paper provided by Mr. Miano and a Google-translation of the German version of the original paper each suggest that the findings misrepresented some important issues and content relevant to the paper.
The author noted that the higher seat height of the Balans was also rated positively for all users. He also wrote that all four of the subjects experienced some degree of discomfort the different versions of Balans chairs, but went on to describe the considerable variability in ratings between models. The chair that received the most positive ratings was the Balans Variable, which received positive scores by all users and “was found pleasant by all users”. Dr. Kruger noted that users continued to sit on this chair, without knee supports after the seating trials.