Archived Articles 2004
Topics of Interest
- Ergonomics For Students.
- How Ergonomics is being used to improve Child Safety Seat Installation?
- Recent research to improved hand/wrist postures with computer use.
As students head back to school whether, primary, high school or university, the term ahead is going to be exciting, busy and…. productive. While working away on the seemingly never ending array of assignments, lab reports, and exams, students should consider the best way to get the job done.
Ergonomics is a term that is widely used in the workplace, yet it seems to render little significance in one's everyday life. In the workspace of a student, unlike the traditional workplace, there are no guidelines describing "ideal" working conditions.
Students have the challenge of multi-tasking and managing what sometimes seems like a thousand things at one time. With productivity being the main goal, efficiency is sometimes overlooked. Sitting in lectures/classrooms, carrying a backpack, and prolonged sessions of reading and writing all contribute to the musculoskeletal symptoms experienced by students. Applying a few simple ergonomic principles to your daily regime can help to create a more favourable learning environment. Younger students may need their parents help and reminders to help reduce the physical stresses that backpacks and computer workstations place on them.
Backpacks
Since lockers are not always available, students are often forced to carry all of the materials they will need for the day with them. As a result, strains of the shoulder, neck, back and arm musculature may be frequent and common.
Design
When choosing a backpack, look for a design with:
- Wide, padded, adjustable shoulder straps
- Lumbar support
- Waist belt
- Compartmentalization for better weight distribution
- Features to suit your body type and the load you intend to carry
Packing
Leave yourself a few extra minutes in the morning rush to properly load your backpack. Distribute the weight evenly, with the heaviest items securely placed at the bottom of the pack, closest to the body. This will help to reduce strain on the shoulders and encourage neutral postures.
Carrying
Backpacks are most effective when they are carried based on their design. Avoid carrying the pack over one shoulder or by hand. This creates uneven loading of the musculoskeletal system and can contribute to strains and fatigue (Pascoe et al., 1997). Using both shoulder straps and ensuring a proper fit will allow you to hold the load close to your body.
Limit the amount that you transport in your backpack…think bare essentials! Try to leave textbooks and other heavy items at home. As a basic guideline, try to avoid carrying more than 10% to 15% of your body weight. Overloaded backpacks can significantly increase lumbosacral forces and have a permanent, destructive impact on posture and spinal health, (Goh et al., 1998 & Whittfield et al., 2001). Consider buying a small backpack - it will help to control the amount that you are able to carry!
Workstation
Unlike an office setting, which can be modified to suit an individual's specific anthropometrics and needs, students often are required to accommodate any number of "one-size-fits-all" scenarios. Lecture hall desks and library cubicles can be rigid and uncomfortable and chairs are often non-adjustable. A basic understanding of body mechanics can help you utilize good working postures to increase comfort.
Sitting
Ensure that your feet touch the floor (or make a footrest), allowing you to keep your knees bent at a 90 degree angle. Crossing your legs or sitting on them requires excessive knee flexion and can add compressive forces at the back of the leg.
Try to sit up straight! Pull your chair in close to your desk and keep your back against the chair, attempting to maintain the natural curvature of your back. This will reduce the strain on your muscles and help to keep your attention focused on the task at hand. Attempt to keep your ears in line with your shoulders (which should be slightly pulled back and not rounded) to reduce strain on frequently used neck musculature.
There are a number of postural enhancers available that can help to keep you comfortable. Low back supports that can be used with any chair, as well as neck supports, are helpful and can reduce muscular fatigue when used properly.
Reading
Maintaining static postures for long durations, especially awkward ones, can lead to considerable muscular fatigue and soreness. Usually, we tend to ignore symptoms until they become unbearable or prevent us from continuing with our work. Look for early warning signs and symptoms such as sore eyes, neck and back pain and a general lethargic feeling throughout the body. As muscles tire, slouching and other poor postures become more likely. Take regular breaks or change your position to help maintain good postures. This can also have a beneficial effect on your level of concentration.
It can also be helpful to use a bookstand to keep the book in line with your line of sight so that you can maintain neutral neck and spine postures. Ideally look for a height-adjustable, portable stand able to accommodate the height at which you are sitting.
Reading should not be done in the prone position (lying on your stomach) since it will lead to neck strain and hyperextension of the spine. Lying on your back is acceptable, as long as the torso can be raised while maintaining a neutral spine. Also, ensure that adequate lighting is available to help reduce the strain on your eyes.
Regular physical activity is also an integral part of maintaining a healthy and productive student life. The benefits include improved cognitive performance and health status and decreased stress levels and anxiety.
Next time you are lugging that over-stuffed backpack across campus or studying in an uncomfortable position, consider the potentially long-term consequences for your body. Attempt to work efficiently so there will be more time for you at the end of the day. After all, learning should not be a painful experience, but a rewarding one!
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How Ergonomics is being used to improve Child Safety Seat Installation?
Adapted from Sarno, Fox and Potvin (2004)
If you are a parent you are probably aware of the legislation and safety literature surrounding the use of child safety seats. Motor vehicle accidents are the leading cause of death in children over one year of age (Johnston, Rivara, & Soderberg, 1994). However, did you know that in a 2002 study, more than 80% of car seats reviewed were found to be improperly installed (Biagioli, 2002)? When used properly, child safety seats can reduce death by 71% for infants and 54% for toddlers. What is the reason for this high frequency of errors? Possible explanations include engineering/design problems, physical difficulty, and/or cognitive complexity (Wegner & Girasek, 2003).
In a recent study completed out of the University of Windsor, funded by Auto21, researchers examined the physical demands, specifically the postures and forces, which were necessary to correctly install both rear and forward facing child safety seats. Given the excessive prevalence of installation errors, the researchers felt it was critical to determine whether the errors were related to the physical demands of installing the seat and set out to quantify the actual physical demands required in this task.
To do so they recruited 31 volunteers, who had children that use child safety seats, to take part in the study. The subjects were videotaped while installing their own child safety seat and also securing their child in the seat. If the seat was improperly installed, the errors were recorded and the subject was required to re-install the seat. A force gauge was used to measure three forces: the magnitude of force needed to tighten the tether, the harness, and the seatbelt. A subjective questionnaire was completed to determine the perceived physical exertion and task complexity associated with each task. Still photos of seatbelt, harness, and tether tightening postures were captured from the videotape. The snap shots were then used to give a full assessment of the demands on the body when installing the car seats.
Results
Sixty-two errors were observed in total. Harness errors accounted for 60% of all rear facing errors and 47% of all forward facing errors. In conclusion, 84% of the forward facing group made errors and 67% of the rear facing group made errors, which could lead to serious injury of the child in the case of an accident.
In terms of the physical stress on the individual installing the seat, the compression limit did not exceed the NIOSH limit value (3400 N). However, 54% of the population would be unable to completely install the forward facing safety seat and 20% of individuals would be unable to completely install rear facing seat, based on strength capability compared to 75% of the female population.
Child safety seat installation, both forward and rear facing combined, is too physically demanding for 37% of the population. Biagioli (2002) stated that 80% of child safety seats are improperly installed, and the current study states that 37% of individuals do not posses the physical strength necessary to install them, thus the task's physical demands may account for 46% of installation errors.
What does this study tell us? Firstly, the results of this study emphasize the need for car seat redesign, making installation easier and improving child safety seat-vehicle compatibility. It also demonstrates that factors, other than physical ability to install the seat, must also be accounting for the large errors in installation. As such a thorough examination of the human factors or cognitive component of the installation of a car seat may also be required. A study conduct in 2003, examined the installation instructions for a variety of Child Safety Seats and found that most of the instructions were worded at a higher reading level than the general consumer population. As such, this study lends evidence to a possible misinterpretation or mismatch between the user and the interpretation of the instructions.
The researchers also found a great deal of difference between the style of child seat and the ability of the individual to install it. So what should we keep in mind when we chose or install a child safety seat?
- When choosing a child safety seat, try it out in your own car before purchasing it or make sure you can bring it back if it does not fit properly. Not all child seats fit well in all vehicles.
- Be sure the person who will be placing the child in the seat is able to do so. Grandparents may have more trouble and if they are a primary person using the safety seat then their abilities will need to be considered.
This area of research has such significant applicability to our every day lives yet little research has actually been completed. However, one new program is being offered through DaimlerChrysler. The "Fit for a Kid" Program is a free service that provides trained personnel to instruct parents on proper usage of child safety seats and to provide inspections to all vehicles, not just Chrysler, Dodge and Jeep vehicles, to help ensure children are kept safe. The program goes so far as to provide a loaner seat in case a damaged or recalled seat is found. The program is offered by appointment at participating Five Star Chrysler/Jeep®/Dodge dealers across the U.S. and Canada. Fit for a Kid is open to all families, no matter what make or model vehicle they drive.
If you are interested in more information on how to install a Child Safety Seat please refer to the following websites:
http://www.nhtsa.dot.gov/people/injury/childps/csr2001/csrhtml/infants2_Guide.htmlty
http://www.daimlerchrysler.ca/ffak/en/fitforakid.html
References
Biagioli, F. (2002). Proper use of child safety seats. American Family Physician. May 15, 65(10): 2085-090.
Johnston, C., Rivara, F.P., & Soderberg, R. (1994). Children in car crashes: Analysis of data for injury and use of restraints. Pediatrics. 93(6): 960-965.
Waters, G. et al. (1993). Revised NIOSH equations for the design and evaluation of manual lifting tasks. Ergonomics, 36(7): 749-776.
Wegner, M.V., & Girasek, D.C. (2003). How readable are child safety seat installation instructions? Pediatrics. 111(3):588-591.
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Recent research to improved hand/wrist postures with computer use.
Left hand mousing
When examining the posture of a worker in an office setting the hand/wrist postures is one of great concern. Many jobs require not only input from a keyboard but a great deal of mousing as well. Mouse use has been associated with shoulder flexion, abduction and external rotation, wrist extension, pronation and ulnar deviation. When mousing with the right hand, the upper extremity is often placed in these postures due to the design or layout of the keyboard. The number pad located to the right of the letters on the keyboard increase the mouse distance from the centre of the worker. This results in increased shoulder abduction and muscular load (Cook and Kothiyal, 1998, Karlqvist et al 1998). One solution provide and included in the CSA Guideline on Office Ergonomics is to have right hand mouse user learn to mouse with their left hand, to the left of the keyboard. As there is no number pad, the theory is that the shoulder abduction and muscled activity should be reduced. However, until recently few studies had been completed to prove or disprove this theory. Delisle et al, 2004 have recently completed a study and provide the following information regarding left versus right hand computer mouse use. The researchers studied 31 right hand mouse use workers. The tested them using a computer task that required the use of both the keyboard and the mouse. The participants were required to complete the computer task at the beginning, immediately after a training session and one month after the training session. Part of the training recommended mousing with the left hand. After the training session 16 of the subjects switched to left hand mouse use.
Results
Overall all subjects demonstrated reduced shoulder abduction, flexion and wrist extension after the training session. The 16 subjects that switched to left hand mouse had a greater reduction in shoulder abduction, flexion, and wrist extension than the right hand mouse users. Additionally, the left hand mouse user demonstrated reduced external rotation and elbow flexion. However, mousing with the left hand required 15 - 22% more time to perform the task than right hand use and the perception of difficulty and discomfort was greater with left hand mouse use than right hand mouse use.
Discussion
Although these results are promising in the demonstration of improved posture with left hand mouse use, the study did not include an assessment of the muscle activity or the number of errors made using each of the conditions. It would be interesting to see if, although there were postural improvements, that there was also concomitant increase in the muscle activity and number of errors. This would be logical, as most of the left hand mouse users would be learning new tasks. Most people demonstrate decreased, an increase in the number of errors and repeat movements when learning a new task. This would logically increase the muscle activity. However, studying the muscle activity when completing these task and implementing a follow up period after a greater time period may demonstrate adjustment to the new task, increased accuracy and a decreased muscle activity. This would be a good area for future research.
Guidelines for Left hand mouse use
Provide yourself with a period of adjustment
As you would be basically learning a new task, your accuracy may be decreased and therefore the number of errors may increase. This could increase your movements and therefore your muscular activity and fatigue. Also affected could be your time to complete tasks and your overall productivity.
Do not switch cold turkey but gradually increase the time you mouse with the left hand to provide time to learn and the muscles to adjust.
If you cannot get used to mousing with the left hand, and you rarely require the number pad, investigate the purchase of a keyboard without the number pad or perhaps a left handed keyboard in which the number pad is on the left hand side.
Continue to practice good ergonomics positioning when keying and mousing.
Support the forearms where possible on the desktop or through the use of the arm rests on the chair.
Wrist and Foream Support
Wrist supports are widely available products that are market to support the wrists and help you attain a neutral wrist posture. However, these supports are not meant to be resting pads for the heels of the hand. They should be use intermittently when the hands are resting and not when the fingers are moving and pressing the keys of the keyboard. Forearm support however, has been shown to increase comfort, reduce neck and shoulder muscle activity, extreme ulnar deviation and the time spent in deviated postures especially with mouse use. A recent study examined the effect of using a wrist rest when the forearms were supported and the forearm support result in a decrease in upper extremity muscle loads and a decrease in the lateral deviation of the wrist. The study demonstrated benefits to providing forearm support when keying and mousing regardless of whether a wrist rest was use or not.
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