Rethinking Sitting and Seating

Transcription

1 Beyond Ergonomics (???) Rethinking Sitting and Seating: ErgoExpo 2010, National Rani Lueder and Dr. Ergonomics Jenny Pynt Conference and Exposition 2013 I m going to talk about Toto, I have a feeling we re not in Kansas anymore Dorothy, Wizard of Oz Rani Lueder, CPE Ergonomics Inc. Austin, Texas rani@humanics-es.com Trends in seating Anterior postures and ligaments Ligaments and proprioception Intradiscal pressures and sitting Near vision and the Trapezius The elephant in the room Recent progression of seating Increasingly adjustable seating (mid-1970 s on?) Passive ergonomics (early 1980 s -?) Dynamic seating (early 1980 s -?) Active sitting (late 1990 s or early 2000 s) Intelligent seating (on its way?) Courtesy of Cindy Burt, OTR, CPE Dynamic seating Seat intermittently continually moves redistributes forces acting on users. As users change position chairs realign their postures. Seat demonstrates a shifting center of gravity in synchrony with the user. Rotatory seat movements. Rotatory seating Lengsfeld, M; Van Deursen, DL; Rohlmann, A; Van Deursen, L; Griss, P. (2000) Spinal load changes during rotatory dynamic sitting. Clin Biomech. 15(4), O Sullivan, K; McCarthy, R; White, A; O Sullivan, L; Dankaerts, W (2012) Lumbar posture and trunk muscle activation during a typing task when sitting on a novel dynamic ergonomic chair. Ergonomics. 55(12), Van Geffen, P.; Molier, B. I.; Reenalda, J.; Veltink, P. H.; Koopman, B. F. J. M. (2008) Body segments decoupling in sitting: Control of body posture from automatic chair adjustments. J Biomech. 41(16), Van Geffen, P; Reenalda, J; Veltink, PH; Koopman, BF (2008) Effects of sagittal postural adjustments on seat reaction load. J Biomech. 41(10), van Deursen, D. L.; Lengsfeld, M.; Snijders, C.; Evers, J. J.; Goossens, R. (2000) Mechanical effects of continuous passive motion on the lumbar spine in seating. J Biomech. 33(6), ErgoSystems, Inc.

2 Active sitting Schult, T. M., E. R. Awosika, S. K. Schmunk, M. J. Hodgson, B. L. Heymach & C.D. Parker (2012) Sitting on stability balls: biomechanics evaluation in a workplace setting. J Occup Env Hyg. 10(2), Grooten, W.J.A., Conradsson, D., Ang, B.O., Franzen, E. (2013). Is active sitting as active as we think? Ergonomics, 56(8), Prolonged sitting Prolonged sitting and health Prolonged sitting is a serious metabolic health problem caused by pathogenic mechanisms: low energy expenditure accumulation of visceral fat and low-grade system inflammation; impaired endocrine function of skeletal muscles malfunction of organs and tissues. Ekblom-Bak, E. Ekblom, B. (2012). Prolonged bouts of sitting is a metabolic risk factor. Lakartidningen 109 (34-35): Thorp AA, Owen N, Neuhaus M, Dunstan DW. Sedentary behaviors and subsequent health outcomes in adults a systematic review of longitudinal studies, Am JPrev Med 2011;41(2): (Dunstan et al op cit). Dunstan, D.W., Howard, B., Healy, G.N., & Owen, N. (2012). Too much sitting- - a health hazard. Diabetes Res Clinical Practice, 97(3), Prolonged sitting: Whitehall II Prolonged sitting and health Sitting time not associated with obesity. Prior obesity was prospectively associated with time spent watching TV per week but not other types of sitting. Pulsford, R.M., Stamatakis, E., Britton, A.R., & Brunner, E.J. (2013) Sitting behavior and obesity: Evidence from the Whitehall II study. Am J Prev Med, 44(2), Prolonged sitting is a risk factor for all-cause mortality, independent of physical activity. Prolonged sitting explained 6.9% of the mortality risk. Questionnaire data from individuals 45 years+ from parts Australia. van der Ploeg, H.P., Chey, T., Korda, R.J., Banks, E., & Bauman, A. (2012) Sitting time and all-cause mortality risk in 222,497 Australian adults. Archives of Internal Medicine, 172(6), ErgoSystems, Inc.

3 Active sitting Refocusing on anterior postures Less postural sway and less muscle activity were observed during active sitting, compared with sitting on a conventional office chair. Grooten, W.J.A., Conradsson, D., Ang, B.O., Franzen, E. (2013). Is active sitting as active as we think? Ergonomics, 56(8), Courtesy of Cindy Burt, OTR, CPE Anterior postures and intradiscal loads Anterior postures & loads on spine Intradiscal loads on the spine are almost twice as high when flexing forward unsupported and almost three times higher than relaxed sitting. Wilke, H.-J., Rohlmann, A., Neller, S., Graichen, F., Claes, L., & Bergmann, G. (2003). ISSLS prize winner: A novel approach to determine trunk muscle forces during flexion and extension: A comparison of data from an in vitro experiment and in vivo measurements. Spine, 28(23), Wilke, H. J.; Neef, P.; Caimi, M.; Hoogland, T.; Claes, L. E. (1999) New in vivo measurements of pressures in the intervertebral disc in daily life. Spine. 24(8), Static forward leaning (anterior) postures led to dramatic increases in upper and lower back loads. Harrison, D. E.; Colloca, C. J.; Harrison, D. D.; Janik, T. J.; Haas, J. W.; Keller, T. S. (2005) Anterior thoracic posture increases thoracolumbar disc loading. European Spine J. 14(3), Ligaments and anterior postures... Anterior postures and viscoelastic creep Prolonged exposure to repetitive lumbar flexion-extension is triggered by an acute inflammation in the viscoelastic tissues that is characterized by lingering residual creep, pronounced changes in neuromuscular control and transient changes in lumbar stability. Solomonow, M.; Zhou, B. H.; Lu, Y.; King, K. B. (2012) Acute repetitive lumbar syndrome: A multi-component insight into the disorder. J Bodyw Mov Ther. 16(2), Solomonow, M., Baratta, R. V., Zhou, B. H., Burger, E., Zieske, A., Gedalia, A. (2003). Muscular dysfunction elicited by creep of lumbar viscoelastic tissue. J Electromyography & Kinesiology. 13(4), Solomonow, M. (2009) Ligaments: A source of musculoskeletal disorders. J Bodywork & Movement Therapies. 13(2), ErgoSystems, Inc.

4 Static postures and ligament damage Prolonged sitting and ligaments During exposure to flexed postures for prolonged periods, as in sitting, the posterior passive elements of the spine can experience viscoelastic creep. De Carvalho, D.; Callaghan, J.P. (2011) Passive stiffness changes in the lumbar spine and effect of gender during prolonged simulated driving. Intl J Industrial Ergonomics. 41(6), Solomonow, M.; Baratta, R. V.; Banks, A.; Freudenberger, C.; Zhou, B. (2003) Flexion-relaxation response to static lumbar flexion in males and females. Clinical Biomechanics. 18(4), Solomonow, M.; Zhou, B. H.; Lu, Y.; King, K. B. (2012) Acute repetitive lumbar syndrome: A multi-component insight into the disorder. J Bodyw Mov Ther. 16(2), Prolonged loading increases injury risk destabilizes the spine laxity viscoelastic tissues (Dolan, Green, 2006; Le et al, 2009) Dolan, Katherine J; Green, Ann (2006) Lumbar spine reposition sense: The effect of a 'slouched' posture. Manual Therapy. 11(3), Le, B.; Davidson, B.; Solomonow, D.; Zhou, B..; Lu, Y.; Patel, V.; Solomonow, M. (2009) Neuromuscular control of lumbar instability following static work of various loads. Muscle Nerve. 39(1), Solomonow, M.; Baratta, R. V.; Banks, A.; Freudenberger, C.; Zhou, B. H. (2003) Flexion-relaxation response to static lumbar flexion in males and females. Clin Biomech. 18(4), Solomonow, M; Zhou, B-H; Baratta, R V; Burger, E. (2003) Biomechanics and electromyography of a cumulative lumbar disorder: Response to static flexion. Clin Biomech. 18(10), Solomonow, M; Baratta, R V; Zhou, B-H; Burger, E; Zieske, A; Gedalia, A. (2003) Muscular dysfunction elicited by creep of lumbar viscoelastic tissue. J Electromyogr Kinesiol. 13(4), Ligaments and proprioception Ligaments stabilize joints, but are also important sensory organs that provide proprioceptive input to the CNS / Central Nervous System. Chaitow, L. (2009) Ligaments and positional release techniques? J Bodyworks & Movement Therapy. 13, 2, Based on Solomonow, M. (2009) Ligaments: a source of musculoskeletal disorders. J Bodyworks & Movement Therapy. 13, 2, Ligaments and anterior postures Only 10 minutes of static postures with lumbar flexion muscle spasms and creep in the lumbar viscoelastic tissues. microdamage to collagen structures and inflammation. Solomonow, M.; Zhou, B. H.; Lu, Y.; King, K. B. (2012) Acute repetitive lumbar syndrome: A multi-component insight into the disorder. J Bodywork & Movement Therapy. 16(2), Solomonow, M; Zhou, B-H; Baratta, R V; Burger, E. (2003) Biomechanics and electromyography of a cumulative lumbar disorder: Response to static flexion. Clinical Biomech. 18(10), Solomonow, M; Baratta, R V; Zhou, B-H; Burger, E; Zieske, A; Gedalia, A. (2003) Muscular dysfunction elicited by creep of lumbar viscoelastic tissue. J Electromyogr Kinesiol. 13(4), Ligaments and anterior postures Lumbar support A significantly reduced lumbar spine reposition sense after slouching for 300 seconds. A slouched 5 min posture increased reposition error. Dolan, KJ; Green, A (2006) Lumbar spine reposition sense: The effect of a 'slouched' posture. Man Ther. 11(3), ErgoSystems, Inc.

5 Trapezius loads and near vision Near vision places demands on the trapezius Richter, H., Zetterberg, C., Forsman, M. (2013) Temporal dependence of Trapezius muscle activation during sustained eyelens accommodation at near. Duffy, Vincent: Digital human modeling. Springer Berlin Heidelberg. 8026, Richter, H., Banziger, T., Abdi, S., Forsman, M. (2010) Stabilization of gaze: A relationship between ciliary muscle contraction and Trapezius muscle activity. Vision Res. 50(23), Richter, H., Banziger, T., Forsman, M. (2011) Eye-lens accommodation load and static Trapezius muscle activity. Eur J Appl Physiol 111(1), Zetterberg, C., Forsman, M., Richter, H. (2013) Effects of visually demanding near work on Trapezius muscle activity. J Electromyogr aphy & Kinesiology. 23(5), Thank you! Rani ilueder, CPE Ergonomics Inc. Austin, Texas rani@humanics-es.com ErgoSystems, Inc.