Background and Purpose. To assess the reproducibility and validity of the six-minute walk test (6MWT) in men and women with obesity in order to facilitate evaluation of treatment outcome. Method. A test - retest design was used to test reproducibility and a comparative design to test known group validity. Forty-three obese outpatients (16 male), mean age 47 (21-62) years, mean body mass index (BMI) 40 (3-62)kg-m-2 performed the 6MWT twice within one week. Intraclass correlation (ICC1.1) and measurement error (Sw) were calculated from the mean square values derived from a one-way repeated-measures ANOVA (fixed effect model). The reproducibility was also analysed by means of coefficient of variation (CV) and the Bland Altman method including 95% limits of agreement. The variance of the distance walked was analysed by means of regressions. The known group validity of the 6MWT (distance walked and the work of walking) in obese participants was shown by comparisons with 41 lean participants (18 male), mean age 47 (24-65) years, mean BMI 22.7kg-m-2 (19-25). Results. The obese group walked 534 m (confidence interval [CI] 508-560 the first and 552 m (CI 523-580) the second walk (p < 0.001). Sw was 25 m, CV 4.7%, ICC1.1 was 0.96. The limits of agreement were -46 m+80 m. The validity tests showed that they walked 162 m shorter (p < 0.001) and performed much heavier work (p < 0.001) than the lean group. In the obese group, BMI alone explained 38% of the variance of the distance walked. Conclusions. The 6MWT showed good reproducibility and known group validity and can be recommended for evaluating walking ability in subjects with obesity. For individual evaluation, however, an improved walking distance of at least 80 m was required to make the difference clinically significant. Despite shorter walking distance the obese participants performed heavier work than the lean. Copyright © 2008 John Wiley & Sons, Ltd. (Source: Physiotherapy Research International)
New Ergonomics Society President promotes ergonomic approach to usability
Overlap in fields of interest …
“Tom Stewart, joint Managing Director of System Concepts Ltd (www.system-concepts.com), one of the largest independent usability and ergonomics consultancies in Europe, has recently been appointed as President of the Ergonomics Society(http://www.ergonomics.org.uk/).
A well known international expert on standards in usability and ergonomics, Tom has been enthusiastically promoting the importance of a user centred approach to the design of technology for over 30 years.
“In my role as President, I want us to work closely with other professional groups interested in how people use computer technology to encourage an ergonomics approach to usability. In this way we can try and make sure that technology improves our lives and reduces stress rather than contributing to it” explains Tom.
“Although taking usability seriously has become more widely recognised as essential to our successful use of technology, many people confuse it with simply trying to make websites easier to use. A usable product or system is one which is effective, efficient and satisfying for its users.”
Tom argues that an ergonomist’s approach to usability has three distinct features:
1. We are interested both in computer software and hardware and in the interaction between these and the user.
The Apple iPhone is a good example where the usability of its navigation comes from the way the physical properties of the touch screen interact with the interface software to provide a compelling user experience.
2. We recognise and value the importance of individual differences in task performance and preferences.
Understanding and recognising that everybody is different, means that to make a system usable we must design for the whole range of potential user capabilities, not the average, the easiest, or the ‘one just like me’. In this way accessibility for all users is integral to our approach to design, not just an afterthought or something that can be add on later.
3. We are task focussed.
Interfaces designed by marketers and graphic designers can look fantastic and make a great first impression, but unless they also allow you do what you want to do efficiently and effectively, this effort is largely wasted. An ergonomics approach makes sure you first understand what people really want to do and that they can do it which, in combination with great design, will produce a satisfying experience for the user.
Tom brings a wealth of experience to the Ergonomics Society. He started his ergonomics career as a founder member of Brian Shackel’s Human Sciences and Advanced Technology Research group at Loughborough University in 1970. After several research and consultancy positions he joined System Concepts Ltd in 1983 and became MD in 1986.
Chairing the British Standards Applied Ergonomics Committee (PH9) and the sub-committee (TC159/SC4) of the International Standards Organisation which is responsible for the ergonomics of human-system interaction (including ISO 9241 and ISO 13407), he is also Convenor of the European Committee for Standardisation (CEN TC122 WG5) working group on VDU ergonomics.” (Continued via E-consultancy.com) [Ergonomics Resources]
Estimating the Elbow Carrying Angle With an Electrogoniometer: Acquisition of Data and Reliability of Measurements
A scientific paper on the lifting capacity of the elbow …
“The carrying angle of the elbow is defined as the angle formed by the long axis of the arm and the long axis of the forearm in the frontal plane.1 The carrying angle value and its pathologic variations are important in the management of elbow fractures2,3 and in the diagnosis of diseases of the lateral and medial epicondyles.4
Based on the theory of general rigid body motion, in 1976, Morrey and Chao1 computed the carrying angle by isolating the 3-dimensional rotation occurring at the elbow joint in 2 cadaveric specimens. They obtained 10° in full extension of the elbow and observed a linear decrease of the carrying angle with flexion. Since then, several authors have measured the carrying angle in vitro using mechanical instrumentations, hinged boards, or goniometers rigidly attached to the humerus5; kinematics or geometrical computations6; or radiographs,7 thus obtaining results not always in agreement with those reported by Morrey and Chao.1 The main reasons for this are differences in the definition of the angle and variations in the measuring instruments.
Few investigators have studied the carrying angle in vivo. Paraskevas et al8 measured the carrying angle in full extension in 600 adults using a special goniometer and compared these values to measures obtained radiographically. Yilmaz et al9 adopted a universal standard goniometer to estimate the full extension carrying angle in healthy volunteers.
Van Roy et al10 adopted a protractor goniometer and an electromagnetic tracking device to estimate the carrying angle in full extension and also during flexion of the elbow joint. They noted the carrying angle is an important anatomic feature when restoration of the elbow’s function is required. In clinical practice, the carrying angle generally is assessed in full extension by radiographs or by a standard goniometer to evaluate reduction of distal humerus or radial head fractures.11,12
This study examined a noninvasive method for evaluating the carrying angle in vivo in full extension by using a digitizer suitable for orthopedic applications to acquire easily identifiable anatomical landmarks on the arm and forearm. An experimental analysis of reliability was performed by comparing repeated acquisition by the same operator and also by 2 different operators with varying levels of expertise. The major advantage of this method, other than its simple derivation, is the possibility of being adapted to a commercial digitizer and easily being used in computer technologies for assisted medical treatment during practical clinical application by providing a graphic display and qualification of anatomic and functional features of the joint.
Materials and Methods
This study received approval from the local ethics committee, and written informed consent was obtained from all participants. The right and left arms in 37 adults (17 men and 20 women) were measured. Patient age ranged from 41 to 81 years (mean age, 60.5±12.1 years). In 2 adults, only right arms were measured, obtaining a total of 72 measurements. All participants were healthy and had no symptoms or signs of relevant pathologies affecting the shoulder, elbow, and wrist joints.” (Continued via Ortho Supersite) [Ergonomics Resources]
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- The Future of Computer-assisted Surgery (CAS) in Sports Medicine.
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- In Search of a Gold Standard of Knee Cartilage Defect Topographical Documentation: “Freehand” Arthroscopic Mapping and Introduction of New Concepts.
- Computer-assisted Double Level Osteotomy for Severe Genu Varum.
- Navigated Open Wedge High Tibial Osteotomy.
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- Editorial Comments.
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