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What is International Labors Day? International Labors Day, a significant day dedicated in paying tribute to the Workers is celebrated on May 1st of Every Year. It is also known as ‘May Day’ and ’International Workers Day’ and it is usually declared as National Holiday in India, in order to appreciate and motivate the support […]
De Quervain’s Disease is a cumulative trauma disorder or musculoskeletal injury that can cause thumb pain. A splint may be required 24 hours a day for 4 to 6 weeks.
Occupational Medicine, Vol. 48, No. 3., pp. 153-160, 1998, “Musculoskeletal Problems and Driving in Police Officers,” written by D. E. Gyi and J. M. Porter, Vehicle Ergonomics Group, Department of Design and Technology, Loughborough University, Leicestershire, United Kingdom:
In the above-mentioned study, the Occupational Health Department of a rural police force in the United Kingdom had concerns with relation to driving and its link to musculoskeletal disorders.
“There are now an increasing number of researchers whose work implicates prolonged exposure to car driving as a risk factor for low back pain. However, such epidemiological studies examining the relationship between car driving and back pain or other musculoskeletal troubles are difficult to conduct. Driving as a task involves prolonged sitting, a fixed posture, and vibration, any of which could directly lead to musculoskeletal trouble. It is likely that symptoms arise from multiple relationships and influences, (Rey, P., 1979).”
“These police drivers are also deemed to be at particular risk because of the following:
- They are generally tall males and wear bulky clothing such that seat adjustment may be insufficient to obtain a good posture.
- They drive fleet cars where the seat and suspension are exposed to excessive wear and tear.
- They often have to drive in rapid response situations such that they are exposed to fast acceleration and deceleration.
- Driving is often followed by strenuous physical activity such as lifting and running.
- They spend most of their eight-hour shift driving or sitting in their vehicle.
- They often have to take back-seat passengers, such that tall males are unable to take advantage of any seat adjustments that do exist.”
“In a survey of 2,000 U.S. police officers, the number and types of health disorders reported b these officers over a 6-month period were similar to those found in the general public over a 12 month period, (Hurrel, J., 1984).”
The results of the above-mentioned study agree with the findings of other studies that indicate driving a car is a risk factor for the development of low back pain.
This document was on my web site buttpillow.com about 18 years ago. The “History of Seating in the Western World” begins with Ancient Egypt and ends with ergonomics professionals.
“A History of Seating in the Western World”
“A History of Seating in the Western World” is a research paper based on the Postgraduate Diploma in Ergonomics Research project performed by Kim Gurr under the supervision of Leon Straker, Physiotherapy, and Phillip Moore, Social Sciences, at the Curtin University of Technology in Perth, Western Australia. Unfortunately, Ms. Gurr died before finalizing her research.”
Following are quotes from the above-mentioned research paper:
Seating is Important for Ergonomics
“Seating is an important issue for contemporary ergonomics. Its frequent use by humans and its association with musculoskeletal disorders are just some of the reasons for its importance.”
Ancient History of Seating
“To understand the place of seating in modern Western societies, it is useful to understand its history.”
Modern History of Western Seating
“This paper presents an overview of the ancient history of seating and the modern history of Western seating with…
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SITTING & PRESSURE
By Darren Salinger, M.D., OB/GYN
& Melanie Loomos, Inventor
In modern society, sitting takes up an increasing amount of time, both at home and at work. It has been concluded there is a considerable shift to sedentary work in industrialized countries (3).
1881 Analysis of Contact Stresses
The original analysis of contact stresses which lead to pressure-related problems while sitting was published in 1881 by Heinrich Hertz (5).
6 Hours Sitting May Cause Pressure Sore
A healthy individual can develop a pressure sore in six to twelve hours if left undisturbed in the same position (7). A single pressure sore costs more than $8,000 to heal. The yearly costs of treating pressure sores and related problems have been estimated to be almost $1 billion (9).
One study found that 63 percent of patients who sat for an unlimited period of time developed pressure sores whereas only 7 percent of patients developed pressure sores who sat for maximum periods of two hours (1).
Limiting sitting time is only one starting point in preventing pressure sores. Other possibilities include appropriate posture and pressure-reducing seat cushions (1).
In a test of six pressure-relieving devices, the air doughnut was found to be the least effective in reducing inter-surface pressures. None of the devices tested eliminated the inter-surface pressures generated by sitting in one position (7).
To prevent tissue damage, people must be able to shift their weight or be assisted to alternate pressure points (7).
External Pressure = 1/2 Internal Pressure
Externally measured pressure under the butt bones is only one half of the internal pressure. Given the pressures that are prevalent, Staarink (1995) found it amazing that more people do not get pressure ulcers (1).
Risk Factors for Pressure Sores
Studies have implicated factors such as posture and posture changes, impact loading of tissue, elevated temperature and humidity, age, nutritional status, general health, activity level, body stature and shear stress in the development of pressure sores (4).
Shear Force & Pressure Sores
The interest in shear stems from the observation that shear increases the possibility of causing a pressure sore (6). In 1958, it was Reichel who started to focus attention on shear force, which is defined as a force parallel to a surface (2). It is important to reduce shear force as much as possible (6). Avoidance of shear force is as important as avoidance of direct pressure (8).
Snijders (1984) showed that the inclination and the position of a backrest as well as the angle of the seat surface influence the shear force on the seat (3). The proper combination of backrest and seat inclination can reduce shear forces on the seat and on the sitter.
In tests done on healthy young subjects, it was found that when little shear is accepted, a fixed inclination between seat and backrest should be chosen between 90 degrees and 95 degrees (3). When a person is sitting down, the weight of the body is distributed over the supporting surfaces. The distributed shear and pressure result in forces that act on four major body points:
▪ The Feet
▪ The Butt Bones
▪ The Top of the Hip Bones
▪ The Chest
Shear Stresses Reduced – 90N to 5N
In a study measuring shear stresses on wheelchairs, using healthy young subjects, different seat angles were tested. Previous measurements showed that a total shear force on the seat of a foldable wheelchair could become as high as 90N when the seat is horizontal (2). When the seat slant is 8 degrees forward, the shear force becomes smaller than 5N in healthy subjects (2). The assumption is made that if the unfavorable effect of shear stress can be measured in healthy, young subjects, the effect for the hospitalized geriatric and paraplegic population will be even worse (2).
The enveloping property of a seat cushion is a measure of its tendency to wrap around the object it supports. When the body adopts a sitting posture, the weight of the body is distributed over the supporting surfaces (3). A good enveloping cushion provides a large contact area and a uniform stress distribution (9).
Medium density foam results in the lowest shear stresses and compressive stresses tested. Soft foam results in the next lowest shear and compressive stresses because soft foam tends to “bottom out” and cause pressure from the surface below the foam.
Caution: Temperature Sensitive Foam
Researchers caution against materials in seat surfaces that react to body temperature because there is a risk of rising temperatures and increased humidity which can lead to pressure sores (1), as well as other pressure-related problems.
Researchers conclude that the use of armrests in the case of healthy persons has a very limited pressure-reducing effect but may help stabilize posture.
- Applied Nursing Research, Vol. 12, No. 3, August 1999, pp. 136-142, “Sitting Posture and Prevention of Pressure Ulcers,” written by Tom Defloor, MScN, N.N.; and Maria H.F. Grypdonck, Ph.D., RN, Nursing Sciences, University of Gent, Belgium.
- Scandinavian Journal of Rehabilitation Medicine, 29: 131-136, 1997, “Shear Stress Measured on Beds and Wheelchairs,” written by R.H.M. Goossens, Ph.D.; C.J. Snijders, Ph.D., T.G. Holscher, Mac; W. Chr. Heerens, Ph.D.; and A. E. Holman, MSc.
- Journal of Biomechanics, Vol. 28, No. 2, pp. 225-230, 1995, “Design Criteria for the Reduction of Shear Forces in Beds and Seats,” written by R.H.M. Goossens and C.J. Snijders, Erasmus University, Rotterdam, Faculty of Medicine, Department of Biomedical Physics and Technology, The Netherlands.
- Journal of Rehabilitation Research and Development, Vol. 29, No. 4, 1992, pp. 21 – 31, Department of Veterans Affairs, “Comparative Effects of Posture on Pressure and Shear at the Body-Seat Interface,” written by Douglas A. Hobson, Ph.D., School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh, P.A. U.S.A.
- Journal of Rehabilitation Research and Development, Vol. 27, No. 2, 1990, pp. 135 – 140, Department of Veterans Affairs, “Reduction of Sitting Pressures with Custom Contoured Cushions,” written by Stephen Sprigle, Ph.D.; Kao-Chi Chung, Ph.D.; Clifford E. Brubaker, Ph.D., University of Virginia, Rehabilitation Engineering Center, U.S.A.
- Journal of Rehabilitation Research and Development, Vol. 27, No. 3, 1990, pp. 239 – 246, Department of Veterans Affairs, “Sitting Forces and Wheelchair Mechanics,” written by Paul Gilsdorf, B.S.; Robert Patterson, Ph.D.; Steven Fisher, M.D.; Nancy Appel, P.T., Department of Physical Medicine and Rehabilitation, University of Minnesota, U.S.A.
- American Journal of Nursing, 1987, “Sitting Easy: How Six Pressure-Relieving Devices Stack up,” written by Robin Charges, RN, M.A., M.S.N.; and Bettie S. Jackson, RN, Ed.D., F.A.A.N., Montefiore Medical Center, N.Y., U.S.A.
- Arch. Phys. Med. Rehabil., Vol. 60, July, 1979, “Shear vs. Pressure as Causative Factors in Skin Blood Flow Occlusion,” written by Leon Bennett, MAE; David Kavner, DEng; Bok K. Lee, M.D.; Frieda A. Trainor, Ph.D., Veterans Administration Prosthetic Center, N.Y., U.S.A.
- J. Biomechanics, Vol. 15, No. 7, 1982, “Model Experiments to Study the Stress Distributions in a Seated Buttock,” Narender P. Reddy, Himanshu Patel, George Van B. Cochran, Biomechanics Research Unit, Helen Hayes Hospital; and John B. Brunski, Center for Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, N.Y., U.S.A.
Temporary enforcement policy on monorail hoists in construction Employers whose monorail hoists fail to comply with requirements in the Crane and Derricks in Construction Standard will not be issued citations as long as they adhere to other regulations, according to a recent memorandum. The temporary enforcement policy notes stakeholders identified gaps in the standard regarding […]