Reference: Biol. Bull. 204: 68 – 80. (February 2003)© 2003 Marine Biological Laboratory Collection and Culture Techniques for Gelatinous KEVIN A. RASKOFF1,*, FREYA A. SOMMER2, WILLIAM M. HAMNER3, AND KATRINA M. CROSS4 1 Monterey Bay Aquarium Research Institute, Moss Landing, California 95039-9644; 2 Hopkins Marine Station, Pacific Grove, California 93950-3094; 3 University of California, Los Angeles, California
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Sitting Can Be Good for the Circulatory System HOW THE EMBODY® CHAIR LOWERS HEART RATE Cardiovascular diseases are the leading cause as a significant contributor to this deadly disease. of death and morbidity in industrialized nations, / See Figure 1 / For people increasingly seduced by accounting for about 50 percent of all deaths. Since computer technology—and the sedentary positions it the 1970s, the prevalence, incidence, and mortality encourages—seating solutions that benefit the heart of chronic heart failure have increased (National might help lower the risk of cardiovascular diseases, Institute of Health, 2005), with physical inactivity and ultimately improve people's health. Solution Essay / 2008 Heart rate is increasingly considered an independent risk factor of cardiovascular disease (Ferrari et al., 2005), meaning it has a significant contribution—among established risk factors—to an outcome like cardiovascular disease. Based on a study of 25,000 patients, resting heart rate was shown to be an independent risk predictor of cardiovascular mortalities (Diaz et al., 2005). A reduction in heart rate decreases the work of the heart; therefore, it decreases oxygen demand and energy needs of the heart while simultaneously resulting in an increase in coronary blood flow. That is, as resting heart rate decreases, the risk of death from cardiovascular disease decreases.
In addition to lowering risk, a decrease in heart rate can improve / Figure 1 / Prevalence of Cardiovascular Diseases in Adults Age 20 and cognition. When people feel better, they are less distracted by Older by Age and Sex: 1999–2004 Source: NCHS and NHLBI. their physical state, which can lead to better performance. A relationship between heart rate and cognition was suggested by research conducted in the 1960s and 1970s, which revealed that a Physical inactivity is a risk factor for cardiovascular disease, deceleration in heart rate during the anticipatory period preceding and it is becoming increasingly prevalent. It ranks similarly to a task was associated with improved cognitive performance cigarette smoking, high blood pressure, and elevated cholesterol (McCraty et al., 2006). And in the 1980s, researchers learned that as contributors to heart ailments. When a person's activity level a decreased heart rate allows the brain to receive sensory declines, the rate of heart disease increases. What's more, less- information more often, leading to better cognitive performance active, less-fit persons have a 30 to 50 percent greater risk of (McCraty et al., 2006). developing high blood pressure (New York State Department of Health, 2008). Only 30.9 percent of U.S. adults report engaging in leisure-time physical activity (American Heart Association, 2008). People who don't engage in regular physical activity, and who spend / See Figure 2 / More than ever, people are opting for sedentary a lot of time sitting, are already at risk for cardiovascular disease. If activities rather than active ones.
they can lower their heart rate, they can reduce their risk (Freedman, 2008). It's not only a health-positive factor, meaning that lowering the heart rate can improve one's health, but also a benefit to one's ability to think, since reduced heart rate is associated with improved Work—and play—have changed dramatically since the early 1990s as technology has come to dominate people's lifestyles. People tend Hispanic or Latino to sit too long without moving. In fact, many chairs restrict the body's movement. Ultimately the sitter's internal systems can be affected.
/ Figure 2 / Regular Leisure-time Physical Activity (Note: Regular physical activity is defined as light–moderate activity for N 30 minutes, N 5 times One approach to promoting movement in a work chair would be per week; or vigorous activity for N 20 minutes, N 3 times per week.) to design one with a dynamic seat and backrest. Doing so would NH = non-Hispanic Source: NHIS 2004. Data are age-adjusted for adults age 18+. Sitting Can Be Good for the Circulatory System Solution Essay / 2 require a surface that automatically conforms to a sitter's micro- Embody's narrow backrest, which was inspired by the human movements and distributes weight evenly. This would allow the seat spine, instinctively adapts to the unique shape and movement to take on the greater burden of supporting more weight while of the sitter's spine. It allows people to move freely and naturally, providing stability. It would also reduce seated pressure and increase automatically adjusting to changes in position and the full range of blood circulation to improve oxygen flow and decrease heart rate. postures. It supports the sitter during large, active movements as well as smaller, passive ones. A sitter's arms can move unimpeded Another design aspect that would promote movement is the shape back and forth, which encourages additional air movement into the of the backrest. A work chair with an upwardly tapered backrest lungs. / See Figure 3 / would provide more flexibility to encourage torso movement and allow the sitter's arms to swing freely. Free to move, the sitter's chest Underneath these innovations is the Embody tilt, the mechanism cavity would open up more than in a chair with a conventional wide under the seat that supports the body's natural motion without backrest allows. As a result, unconstricted lungs could enable a sitter creating intrusive pivot points. Freedom of movement with full to take deeper breaths, thus requiring fewer breaths per minute. support results from the tilt's three linked support zones: 1) thoracic, 2) pelvic/sacral, and 3) distal thigh. The zones work Taken together, these features would promote movement while as a system to encourage freedom of movement and avoid the seated. And movement, as research has shown, is the key to good problems associated with static postures, such as dehydration of health. It keeps blood circulating and oxygen entering the lungs to the discs in the spine. feed the brain so people can think better.
To determine the health-positive effects of sitting in the Embody chair, Herman Miller commissioned a research study that measured The Embody chair was designed with an innovative Pixelated six cardiopulmonary variables. All subjects (15 male, 16 female) Support™ system, a matrix of pixels that work together in the seat sat in an Embody chair and a conventional foam-based office chair and backrest to conform to the sitter's movement. Its dynamic with a wide backrest. They sat in each type of chair for at least surface—a mat layer supported by a local spring layer in the seat two hours. During that time, the following metabolic variables were and "H-flexors" in the backrest—contours to the sitter's unique shape to reduce seated pressure while providing stability. • Heart Rate (HR) (beats/min)• Respiratory Exchange Ratio (RER) (unitless) The Embody chair's dynamic • Respiratory Rate (RR) (breaths/min) surface contours to the sitter's • CO2 Output (liters/min) (ml/kg body wt/min) unique shape, and the narrow • Relative O2 Uptake (ml/kg body wt/min) backrest allows the arms to move unimpeded.
• Tidal Volume (Vt) (liters/breath) [Note: Ventilation is RR x Vt (ventilation is units of liters/min); RER is the ratio of CO2 output to O2 uptake (both in units of liters/min).] The order of the chairs was counterbalanced so about half the subjects first sat in the Embody chair and then the conventional chair; the order of the chairs was reversed for the remaining subjects. The subjects were experienced computer users who performed typical office computer tasks while data was recorded in a laboratory setting. All subjects had to meet qualification criteria, which included the following: Sitting Can Be Good for the Circulatory System Solution Essay / 3 • Works with a computer for at least four hours per day • 18 to 55 years old, inclusive • No musculoskeletal injury or pain that would make it difficult to participate in the study • Free of respiratory illness, such as asthma • No consumption of caffeine within one hour before testing • No intake of medications that affect the heart from midnight of previous day to time of testing Results revealed for both genders that heart rates were consistently lower during a majority of the tasks the subjects engaged in while seated in the Embody chair versus the conventional chair. Compared with the conventional chair, heart / Figure 4 / Regression analysis, heart rate and weight; as subject weight rates ranged from 2.6 to 3.4 fewer beats per minute (bpm) for increases, improvements in heart rate while sitting in the Embody chair become more pronounced.
female subjects sitting in Embody while heart rates ranged from 4.6 to 7.9 fewer bpm for the male subjects (Papanek et al., 2008). When the heart rate changes are extrapolated to an 8-hour increased, which indicates that the Embody chair appeared to workday, a 2 to 3 bpm difference adds up to 120 to 130 beats per decrease heart rate more for large subjects than smaller subjects. hour and over 1,000 beats per day. / See Figure 4 / Extrapolation of the difference in beats per hour and day was In another study comparing the Embody chair to two chairs even more dramatic for males. This decrease in heart rate was with foam seats and two chairs with suspension-material seats, not a consequence of subjective comfort or opinion of the chair Embody—with its innovative Pixelated Support system—performed or a placebo. Because of the control methods used in the study, better than other seat constructions in maintaining oxygen levels in including the counterbalanced order of the chairs and all other the tissues surrounding the ischial tuberosities—or "sit bones"—of variables being equal, the significant decreases in heart rate can the seated subjects (Mahksous et al., 2008). When pressure is be attributed directly to the Embody chair—a cardiovascular benefit reduced at the sit bones blood circulation is increased to the lower extremities, which improves the flow of oxygen. Furthermore, while no statistically significant effects of the chair's This has two important consequences. First, the improved design were associated with respiratory rate or tidal volume (the oxygenation of the tissues requires less demand for more blood in ability to take deeper breaths) for either males or females in the the area. Second, the improved circulation helps return blood back study, more analysis indicated that the Embody chair may be to the heart (venous return) which makes it easier for the heart to advantageous from a respiratory perspective for larger subjects, pump (stroke volume). A higher stroke volume allows the heart to particularly users with a Body Mass Index (BMI) over 30 (defined work at a slower pace (decreased heart rate) while still achieving by the National Institute for Health as obese).
the goal of pumping needed oxygen to the tissue (cardiac output). Thus, the heart performs more efficiently, pumping the same Prediction of heart rate from BMI and weight indicated that cardiac output but at a decreased heart rate and heart work.
the Embody chair reduced heart rate when compared to the conventional chair. In addition, the trend lines marking the Embody Few chairs target the ability to improve physiological function and conventional chair started to diverge as BMI and weight for people in sedentary—specifically seated—postures. Embody Sitting Can Be Good for the Circulatory System Solution Essay / 4 is the first chair design that significantly affects heart rate McCraty, Rollin, Ph.D, Mike Atkinson, Dana Tomasino, and Raymond across a variety of office tasks, resulting in a positive impact on T. Bradley, Ph.D. The Coherent Heart: Heart-brain Interactions, Psychophysiological Coherence, and the Emergence of System-Wide the cardiovascular system without altering work productivity. In Order. Boulder Creek, CA: Institute of HeartMath, 2006.
combination with the results from previous studies examining tissue perfusion, the Embody chair demonstrates a unique ability New York State Department of Health, <http://www.health.state.ny.us/ to enhance perfusion to the lower extremities while simultaneously diseases/chronic/cvd.htm> (accessed October 16, 2008).
doing so at a decreased cardiac workload. The decrease in heart Papanek, Marklin and Freier (2008), "Metabolic Study of Office Workers work or decrease in heart rate can lead to a decrease in the risk of Using an Office Chair," Marquette University Departments of Physical Therapy and Mechanical Engineering, 2008. cardiovascular disease for those who sit in the Embody chair, even as they move through the full range of postures. PubMed Central (PMC), U.S. National Institutes of Health (NIH), 2005, (accessed September 12, 2008).
The world of work—and play—demands more use of technology every day. And people are getting more sedentary because of it. Sitters who use a chair that's good for the body by reducing the risk of cardiovascular disease can improve their health as well as Gretchen Gscheidle is a product researcher at Herman Mil er. Educated their cognitive performance. as an industrial designer, Gretchen now applies her creativity and problem-solving skil s in her role as researcher on cross-functional product development teams. She has been the research link in the company's seating introductions beginning with the Aeron® chair in 1994. Her Association AH. , editor. Heart Disease and Stroke. Statistics - 2005 research focuses on laboratory studies of pressure distribution, thermal comfort, kinematics, and usability, as wel as field ethnography and user 8119HDSStats2005Update.pdf> (accessed September 12, 2008).
trials. Gretchen is a member of the Human Factors and Ergonomics Society and represents Herman Mil er on the Office Ergonomics Research Association AH. , editor. Heart Disease and Stroke. Statistics - Committee. Her work has been published in peer-reviewed journals.
heart/1200082005246HS_Stats%202008.final.pdf> (accessed October The late Bill Stumpf studied behavioral and physiological aspects of sitting at work for more than 30 years. A specialist in the design of ergonomic seating, his designs include the Ergon® chair, introduced by Herman Miller Diaz, A., Bourassa, M.G. and Guertin M.C. (2005). Long-term prognostic in 1976 and, with Don Chadwick, the equally innovative Equa® and Aeron value of resting heart rate in patients with suspected or proven coronary chairs. He contributed significantly to the design of the Embody chair prior artery disease. European Heart Journal, 26, 967-974.
to his death in 2006. In that same year, he posthumously received the Ferrari, R., Camp, G., Gardini, E., Pasanisi, G. and Ceconi, C. (2005). Specific National Design Award in Product Design presented by the Smithsonian's and selective inhibition: expected clinical benefits from pure heart rate Cooper-Hewitt, National Design Museum.
reduction in coronary patients. European Heart Journal Supplements, Jeff Weber credits his love of furniture design to working with Bill Stumpf, who designed for Herman Miller for 30 years. Weber joined forces with Stumpf's Minneapolis firm in 1989. That led him to his association with "Heartbeat an indicator of disease risk: study," Danny Rose, Herman Miller. Weber worked with Stumpf on the Embody chair and, after Sydney Morning Herald, September 1, 2008, <http://www.smh.
Stumpf died in 2006, Weber evolved the design at his Minneapolis-based Studio Weber + Associates. In addition to the Embody chair, Weber's study/2008/08/31/1220121048825.html> (accessed September 12, designs for Herman Miller include the Intersect® portfolio, Caper® seating, and the Avive® table collection.
Mahksous, M, Lin F. Influence of chair designs on pressure distribution, For more information about our products and services or to see a list of dealers, tissue perfusion, and skin temperature, Departments of Physical Therapy please visit us at www.HermanMiller.com or call (800) 851 1196.
& Human Movement Sciences, Physical Medicine & Rehabilitation, 2009 Herman Miller, Inc. Zeeland, Michigan Northwestern University, 2008.
® L, Aeron, Avive, Caper, Embody, Equa, Ergon, and Intersect are among the registered trademarks of Herman Miller, Inc. ™ Pixelated Support is among the trademarks of Herman Miller, Inc.
Alastair Baker 9/7/2013 Investigation and treatment of liver disease with acute onset – Local hospital protocol Defined as EITHER sudden onset of jaundice with evidence of liver aetiology OR incidental discovery of raised transaminases in association with symptoms suggesting acute onset Age of onset >3 months