Ergonomics is the science of designing the workplace, machines and work tasks within the capacity and capability of the human body. Its focus is fitting the job to the worker, not the worker to the job.
When workers have to adjust their bodies to do a job, over time there’s a high potential for developing a Cumulative Trauma Disorder (CTD). CTD, as defined by OSHA, is a class of musculoskeletal disorders involving damage to the tendons, tendon sheaths, and the related bones, muscles and nerves of the hands, wrists, elbows, shoulders, neck and back.
By acknowledging the most common CTD risk factors, we present to you the 5.5 Ways To Understanding How Ergonomics Ensures Workplace Safety.
1. Repetitive Movements
The Risk -- Jobs that make workers perform a series of motions every few seconds with little variation produces fatigue and muscle-tendon strain. When not given adequate time to recover, the risk of tissue damage and other musculoskeletal problems increase. A task cycle time of less than 30 seconds is considered repetitive. Also, awkward postures and external force decrease repetitions per minute.
The Resolution -- Allow the body performing repetitive movements to recover from strain and fatigue. Grant workers a 60 to 90-second break where they stop doing the activity. These breaks are recommended every 20 to 30 minutes. Having ideal posture also helps with repetitive movements, since bad posture falls under the risk factor of awkward/prolonged postures and magnify the hazard of CTDs.
2. Awkward/Prolonged Postures
The Risk -- Jobs that include any fixed or constrained body position that’s more than 20 degrees out of neutral is considered awkward. For example, if you work with your wrist bent in 45 degrees of flexion, 40% of your grip strength is lost. This means you have to exert 40% more force to perform the job task, creating strains and sprains that overtime develop into debilitating injuries.
The Resolution -- You have to find the root cause and from there eliminate awkward postures with engineering and administrative ergonomic controls. Considerations of root causes are situations such as work height in relation to the worker or tools forcing awkward postures.
3. Excessive Force
The Risk -- There are two kinds of excessive force: internal and external. Internal forces result from prolonged awkward positions where the body must generate enough internal force to counteract the effects of gravity. External forces are generated when we lift, hold, push or pull an item, where the amount of force depends on where our hands are located in relationship to our body.
The Resolution -- Again, for internal force, you have to find the root cause and correct it with ergonomics. For external forces, like heavy materials handling, the use of mechanical assist devices reduces the risk of injury.
4. Arm/Hand Segmental Vibrations
The Risk -- Prolonged use of vibratory tools breaks down the small capillaries in the fingers, restricting blood flow. Although symptoms of segmental vibration takes years of exposure to experience symptoms, it could result in blanching of the fingers resulting from loss of blood flow.
The Resolution -- Vibration-damping materials such as gloves or tool wraps can control vibrations, so long as they don’t increase the amount of force required to hold the tool.
5. Mechanical Contact Stressors
The Risk -- There are two types of mechanical compression: internal and external. Internal occurs when muscles are held in a static contraction, which reduces blood flow to the nerves. External occurs when parts of the body come into contact with hard or sharp objects.
The Resolution -- Reducing or eliminated prolonged static postures, padding all sharp edges of workstations and tool handles, using tools that don’t end in the palm of the hand and using mechanical aids for hammering are all helpful options.
5.5. Cold Work Environments
The Risk -- Working in cold conditions negatively impacts our musculoskeletal system and tactile sensitivity. When we lose the ability to feel an item, we grip harder to have control over our hands and actually feel the part we are working with. Unfortunately, when gloves are worn to keep hands warm, force required to perform the task may increase.
The Resolution -- Wear a hat or hood, as up to 40% of body heat can escape from the head if left exposed to the elements. Engineering controls such as radiant heaters help warm workers, while shielding work areas from winds reduces chill. When temps drop below 30 degrees, use insulating material on equipment handles.
The overarching theme of the above CTD risk factor resolutions is to balance work demands with worker capacity. On the whole, we tend to work harder than necessary to get jobs done because of awkward postures and poor design. Meaning that working to solve CTDs through ergonomics results in decreased injuries but also increased efficiency.
Ready to learn more about ergonomics and the prevention of CTDs? Call 800-523-5367 or click on the button below to speak with a safety specialist at Arbill.