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Is there a legacy? |
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Though a Federal ergonomics law was repealed in March 2001, the
risks identified in it were never refuted. When knowledge or
suspicion of risk can invoke culpability, did the repeal of the law
relieve corporations from the burden it created or leave them
exposed? According to the rescinded law, Musculoskeletal disorders (MSDs) develop as a result of repeated exposure to ergonomic risk factors. The proposed rule covers the following ergonomics risk factors: Force (including dynamic motions), repetition, awkward or static postures, contact stress, vibration and cold temperatures. In relation to computer use: “MSDs the Ergonomics Program Standard would cover include carpal tunnel syndrome, Epicondylitis, ganglion cyst, tendinitis, rotator cuff tendonitis, DeQuervain’s disease and trigger finger.” Evidence of a legacy may be indicated by this extract: “Reducing these exposures reduces the incidence and severity of work-related MSDs; Work-related MSDs are preventable; and Ergonomics programs have demonstrated effectiveness in reducing risk, decreasing exposure and protecting workers against work-related MSDs.” OSHA concluded that any of the above computer related MSD’s could be eliminated by limiting the use of a keyboard and mouse to no more than a total of four hours per day in the workplace, and even then when under a condition of use described as “a steady manner”. The conclusions pertaining to computer input were that a twisted wrist posture and continuous grip could be identified with MSD causation, even though at the time the reasons were not fully appreciated. Some comments from the archives pertain to computer mouse use, which we maintain is the key culprit in the initiation of a cycle of physiological decline that leads to MSD development in the upper limbs. “When workers have to hold a tool without putting it down, they must maintain the muscles in contraction. Mouse users who grip a mouse constantly because their work requires so much ‘click and drag’ also experience these low but constant forces. Over time, fatigue of muscles and inflammation of tendons occurs.” Argument Against the Conventional Design of Computer Mice OSHA’s findings focus on posture types; which are an indication of the rate at which physiological fatigue will be induced. Neutral Posture, muscles under idle, is the ergonomic gold standard and also the fatigue recovery posture. The most fatigue inducing posture is Static Posture whereby muscles are held under constant contraction. It is to be avoided if possible, and if not then closely managed by work breaks. Dynamic Posture, in which muscles are contracted and relaxed cyclically, is the middle ground. Each muscle relaxation phase allows the muscles to reconnect with the circulatory system allowing some degree of nutrient replenishment and toxin removal. A 2004 study by the National Institute of Occupational Health in Copenhagen, Denmark, used a micro-dialysis technique to extract fluid from muscles during low force muscle activity as well as collecting blood. What they discovered was the development of anaerobic metabolism within muscles under low force contraction. This produced toxic byproducts (e.g. lactic acid) at levels many times higher than those found in the bloodstream at the time of performing the work. This indicates that working muscles do not have full access to the bloodstream when they are being used. This most likely represents one of the “missing links” that can explain the onset of MSD’s physiologically in a task like mousing that does not seem physically demanding. What the Denmark study shows is that there is no unconditionally safe working posture as the practical difference between Static Posture and Dynamic Posture is a differing rate of substrate exhaustion and anaerobic toxin build. Static Posture, continuous muscle activity, produces the most toxins relative to the work duration spent in either posture. The case for physiological fatigue causing MSD’s is now more clearly established, but a second factor or missing link might also help explain why it has taken so long for aches due to fatigue to be recognized as the onset of a MSD problem, and comes from research into a totally unrelated area. This “second factor” will likely impact the management of work scheduling and the need for computer users to take more frequent and “muscle relaxing” work breaks. Cognitive Distraction is a term coined to explain that when we are busy performing thinking work, the brain suppresses low order ache and pain signals to allow us to concentrate. Migraine researchers investigating this neurological process speculate that “thinking circuits” and “pain circuits” overlap in the brain and attenuate (reduce) pain signals, even though the nerves in the vicinity of fatigued muscles are sending ache signals. They are using this process practically in migraine treatment, advising some migraine sufferers to play video games at the onset of symptoms. For most of us playing a video game when you feel a headache coming on would be counterintuitive. We explain Cognitive Distraction in evolutionary terms: it likely evolved at the time when falling over to aches or small pains too quickly could have been the difference between eating lunch and being lunch. Another interesting and recent study indicates that nerve damage releases proteins called cytokines that impact brain function causing malaise or physical fatigue. Cytokine release is considered a bodily defense mechanism, reducing activity so as to allow healing to occur. Nerve damage and cytokine release is now thought to be a possible cause of “sick worker syndrome,” which again has been argued in the past as a psychological explanation of MSD’s and Repetitive Strain Injury. The net impact of Cognitive Distraction is that we cannot rely upon our senses to warn us of fatigue onset at the time of its occurrence. It can also explain much of the “away from computer” manifestations of pain that occur, which are often cited as pointing to the fact that injury occurred as a result of activity away from the computer. Taking Breaks From Work: What Cognitive Distraction also tells us is that there is no perceptive method of detecting fatigue, and so empirical methodologies must be employed to determine when a work break is taken. Breaks must reflect the working posture and respect the physiology of the individual worker. To that end we have developed a break program (called Brakemoor) that employs the 3 R’s of anti-fatigue: Re-Aeration, Relaxation and Recovery. It is a passive muscle relaxation system without the risk of injury associated by asking already fatigued muscles to perform stretch exercises. As fatigue cannot be predicted Brakemoor does not employ work surveillance techniques, also known as productivity profiling, to determine when a break should be taken. Error detection can for many be “black box data,” an analysis of what caused the crash. Brakemoor is a part of an Anti-Fatigue strategy and has been spun out into media versions, audio and video, that you can take with you on your personal media player, and use the same technique you use at work when at home or on planes, or to counter restless nights in hotels. The media version is called Relaxmoor and it has already been accepted as an iTune download. The State of Ergonomics Today, six years after OSHA identified a twisted wrist position and grip as a “recognized MSD risk,” major manufacturers are still making “ergonomic claims” for mice to those designs. Even more new products that claim ergonomic innovation have been launched upon an unsuspecting and needy public. But NONE refer to the OSHA findings or talk about their products in terms of reference used by OSHA, such as static, dynamic or neutral postures. None save for one that it is. Even if the law is repealed, do the findings that OSHA made not serve as a template for change and innovation? OSHA refers to Static or Awkward postures, Dynamic and Neutral. A twisted wrist is a Static Posture creating tension over the flexor muscles in the forearm that provide grip to a mouse and facilitate button clicking. Consequently the recent upright or vertical mouse innovation makes sense. But, this posture change only frees up the wrist pronator muscle at the expense of requiring a higher degree of grip to stabilize and control the mouse. Grip Can Be Classified Under Two Headings, Grasp or Pinch Grasp, like holding the handles of a bicycle, is called a power grip. Most force can be applied in this posture as the fingers and the palm are in intimate contact with the object under flexation. It is however still a Static Posture and so has a higher degree of fatigue induction. Pinch grip is to apply force between thumb and finger(s) with the fingers pointing straight out or under extension. This is the worst form of grip there is. To quote the Australian Dept. of Labor: “Pinch grip strength is approximately only 25 percent of power grip strength. This grip increases the potential for wrist injury because of its effect on tendons.” Researchers in Japan confirm the 25 percent capacity of grasping, which is to say muscles are worked four times harder, as 100 percent Pinch Grip output is equal to only 25 percent of the force achieved by 100 percent output of Grasp grip. They also showed that Pinch grip could only be maintained for 50 percent of the time that Grasp can be maintained. Despite this, upright mice are being hailed as the new ergonomic frontier when in fact they may be placing new and even greater demands on different muscle groups. In what we call “New Posture Syndrome,” we explain that if you change devices to one that uses a different set of muscles the relieved muscles will thank you, and the difference immediately experienced is considered an improvement. It is only three to six months later that the posture now depicted starts to cause problems for the new muscles and tendons used. The new pains are invariably blamed upon that person’s propensity to MSD and not the fact that they have bought another non-ergonomic, ergonomic product. In regards to conventional mice, they ALL employ the Static Postures of twisted wrist and Pinch Grip for cursor manipulation and Dynamic Posture for button clicking. Most vertical mice untwist the wrist. But, vertical mice require Grasp, and one demand’s Pinch Grip. However, the AirO2bic mouse is an example of one that untwists the wrist and does not require grip. In summation the input device industry’s response to the demise of the EP could be seen as, “whew, that was close”, rather than maybe there are lessons to be learned from the millions of dollars the U.S. government spent on researching the issue. The Occupational Safety & Health Act says, “Each employer shall furnish to each of his employees employment and a place of employment free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees.” Even though the ergonomics law was repealed, its findings can be viewed as the recognition of specific hazards. The case in point being the use of a twisted and gripped posture as it pertains to computer mice. Though the principle of undue burden comes into effect, for instance, even if a practicable design of keyboard was developed that eliminated Static wrist twist and Dynamic finger movement, the cost of retraining everyone would make it unduly burdensome. However, the OSHA findings may set a precedent for the requirement to take regular fatigue breaks when working with the current design as the hazard is recognized. In relation to computer mice, the transition to a better design is simple and intuitive. The existence in the market of a mouse design that responds to OSHA’s findings may create a precedent to examine the “management of recognized hazards.” A pilot study with the AirO2bic mouse clinically demonstrated that its substitution for a conventional palm down mouse resulted in a beneficial increase in nerve conduction response. When the median nerve becomes trapped due to Carpal Tunnel Syndrome (CTS), the speed at which signals pass down (and up) a nerve slows. Nerve conduction times greater than four milliseconds are considered diagnostic for CTS. In our study, both CTS positive and negative subjects saw increases in nerve conduction velocities (NCV). Most CTS positive measurements were back below the four Ms diagnostic threshold within three months. CTS negative subjects showed improved nerve conduction placing them further into the normal range, or further away from a diagnosis of CTS. As with all things, in isolation, the above is open to interpretation. “Corporate test,” however is seldom proactive but reactive to a situation that has developed. Consideration as to the design of input devices rendered by the EP is not in isolation. Another prevailing law sets standards for input device design that excludes postures recognized by OSHA as hazardous, though this Law and the standards it sets are for different reasons. Those reasons are Accessibility, which is designing equipment to be more easily adapted to assistive technology for persons with disability. Under what is called Section 508 Law, the US Federal Government must purchase IT that complies with specific standards. In relation to Operable Controls applicable to computer mice it states, “Controls and keys shall be operable with one hand and shall not require tight grasping, pinching, or twisting of the wrist. The force required to activate controls and keys shall be five pounds maximum.” The objective is to make controls more easily usable by those with limited dexterity.Section 508 recognizes CTS as a disability and cites the standards as facilitating easier use by persons so impaired. The irony is that if Section 508 standards were adopted by industry it would make computer access available to a broader spectrum of human capability, while at the same time, by our analysis, most likely reducing the level of disability due to working muscles in a localized fatigue state. Section 508 law came into force on June 21, 2001, three months after the EP was repealed. Federal Government IT business is big business, and as Section 508 is a Civil Rights Law under the ADA, it might create an incentive for manufacturers to design for compliance. Statements of compliance are invited by the Federal Government to assist them with meeting their purchasing criteria. Despite the appearance and disappearance of the EP and the entry into Law of Section 508, the design of the 40 million or so mice sold into the US market each year has not fundamentally changed. They are still wrist twisting and pinching. Yet many manufacturers that make statements of compliance assert full compliance with the standards. Their response to the standard above, is mostly, “controls and keys are operable with one hand and the force required is less than five pounds.” Grasping, pinching, or twisting of the wrist, something that OSHA spent eight years and millions of dollars on as a part of an exhaustive MSD investigation, are not mentioned. Industry is at the mercy of product manufacturers to provide it with tools that reflect the latest safety thinking and incorporate legislative demands. If manufactures do not respond or industry is seen to fail to react then there is the potential for consequential reparation, which is often unduly sought and inequitably applied. The reality is that the design of computer mice has not fundamentally changed in the mainstream market for 40 years. The duration and extent of its use however has. So has the increasing emergence of negative outcomes that can be identified as being associated by the development of fatigue as a consequence of its use. This is based upon a more analytical approach to posture definition and not the arbitrary use of the word “ergonomic.” To close with one last OSHA excerpt from the repealed EP Law: “There is abundant record evidence that early detection and intervention can halt the progression of most MSDs, and reduce their severity. On the other hand, where medical treatment and ergonomic interventions are delayed, it is more likely that conservative treatment will be less effective or will not even be an available option, or that the MSD condition will not be reversible and the employee will be permanently disabled. For example, if carpal tunnel syndrome and other nerve-related MSDs go untreated long enough, damage to the nerves will be irreversible.” FSM Tom Large is president & CEO of Designer Appliances, Inc., a manufacturer of Anti.Fatigue hardware and software designed to manage the impact that fatigue is now understood to have upon computer users. Anti.Fatigue design conforms to Universal Design criteria for products that are more “Accessible and Assistive” to all, including persons with dexterity impairment or disability.
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