Physiotherapy Report on the Kneelsit ergonomic chair

REPORT RE THE KNEELSIT BALANCE CHAIR

Whilst researching for my book "The Seat of Your Pain may be Your Chair", I became very interested in the Kneelsit chair. Having trialled the Kneelsit and in fact spent 6 months writing from it I am now a disciple

Report

The Kneelsit chair is similar in concept to the Balans Kneeling chair. However, all of the problems of the Balans chair, which brought this innovative form of seating into disrepute and caused such poor reviews in the literature, have been overcome in the Kneelsit Balance seat

The problems of the Balans kneeling chair were:-

1) Lack of back support required the erector spinae to work constantly to maintain the lordosis.
If one has a chronic low back condition, the back musclature is already weakened. If the chair requires the back muscles to constantly contract, they will quickly tire in the person with back problems, leaving the seated person in a slumped position, which immediately increases the pressure on the disc
2) Pressure on the shins was quite intolerable in many instances.
3) Ingress and egress from the chair was quite difficult.(Cram & Vinitzky, Drury & Francher, Lander et al, Pheasant.)

The Kneelsit chair overcomes all these problems whilst maintaining the benefits of a forward sloping seat:-
a.) The lumbar support is adjustable from the seated position to support the back through all the available ranges of forward tilt of the seat pan.
The lumbar rest also allows the sitter to recline in a supported position. Thus the erector spinae are relaxed while the lumbar spine lordosis is maintained at all times , not only by the lumbar rest but by the forward inclination of the seat, which allows for a greater degree of extension of the hip joints.

Background to the forward-sloping seat:-

Keegan showed (1953),  when discussing the disadvantages of  the cubist or 90º hip/trunk position in sitting, that this position  is achieved by 60º of hip flexion and 30º of lumbar flexion ∓ pelvic rotation. As a result lumbar lordosis is reduced and the disc pressure increased.
Mandal (1976) was the first to write of the benefits of tilting the seat pan forward, thereby reducing hip flexion and making it easier to maintain lumbar lordosis without active muscle contraction.However Mandal's suggestion the seat should be inclined forward to 15º met with severe criticism because of the weight forced onto the feet, the feeling the chair was ejecting the sitter, and the problems of the clothes rucking (Drury ∓ Francher, Graf et al). It is now universally accepted a forward tilt seat promotes better posture not only by opening out the hip/trunk angle but by altering the centre of gravity (Stewart ∓ McQuilton). The forward tilt seat is particularly beneficial to those involved in intensive keyboarding or desk tasks. 

b.) The Kneelsit chair's adjustable forward tilt seat allows just such an open position of the hip/trunk but there is no sensation of increased weight on the shins no feeling of ejection from the chair, and no sensation of the clothes rucking.

c.) The seat and shin pad of the Kneelsit chair are adjustable to individual lengths of thigh and shin and move to a variety of tilts via the unique axle system. The shin rest is suitably deep and wide to distribute pressure evenly and there is no sensation of undue pressure over the tibiae.

d.) The shin rest drops away to a vertical postion when weight is taken off it to allow ease of ingress and egress.

e.) The unique axle system of the chair allows movement from a reclined position to a forward position without the necessity of adjusting levers. This makes the chair ideal for people working in a keyboard intensive task or a communication/ meeting situation. This ease of movement allows the sitter to change positions frequently, and also allows, if not encourages, movement of the spine from the lordosed-to flexed position, thus improving nutrition to the discs. (Mackenzie)

The Kneelsit Balance Chair combines the best features of seating to ensure an excellent posture no matter what the task.

 

REFERENCES:

Cram J.R., Vinitzky I.,   Effects of chair design and back muscle fatigue.   J. Occ.Rehab. 5 (2) 1995

Drury C., Francher M., Evaluation of a forward sloping chair.  Applied Ergonomics   16. 1. 41-47 1985

Lander C., Korbonn G., De Good D., Rowlingson J.    The Balans chair and its semi kneeling position; an ergonomic comparison with the conventional sitting position.  Spine Vol 12 No. 3 1987

Pheasant S.   Ergonomics, work and health.   Aspen Publications USA 1991

KeeganJ.  Alterations of the lumbar curve related to posture and seating.    J.B.J.S. Vol. 35A No. 3 July 1953

Mandal A.C.  Work chair with a tilting seat.  Ergonomics Vol. 19 No. 2 1976

Graf M., Guggenbuhl U., Krueger H. Investigation on the effects of seat shape and slope on posture, comfort and back muscle activity.   Int. J. Ind. Erg.  Vol. 2,  91-103,  1993

Stewart P., McQuilton G.   Straddle seating for a cerebral palsy child   Physiotherapy. Vol. 73 No. 4  1987

Mackenzie R.   Treat your own back.   Spinal Publication NZ Itd. 1985

18 June 1997