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(Photo: Hauptverband der gewerblichen Berufsgenossenschaften (HVBG))
A most common type of non-fatal occupational health injuries involving lost-work days are sprains, strains and tears. Overexertion is the most common cause of sprains, strains and tears, accounting for approximately 50% of all cases. It is also the most costly type of injury.
Overexertion-The Leading Cause of Back Injuries
Overexertion injuries are the result of excessive lifting, pushing, pulling, holding, carrying or throwing an object. These injuries, which involve the nerve, tendons, muscles and supporting structures of the body, are considered musculoskeletal disorders (MSDs).
Low-back disorders are associated with work-related lifting and forceful movements and possibly whole body vibration (WBV), which occur when mechanical energy oscillations are transferred to the body as a whole. Typical exposures for WBV include driving automobiles, trucks and operating industrial vehicles. Other physical workplace factors found to have an association with back disorders include awkward posture and heavy physical work, although these risk estimates are more moderate than lifting and forceful movements. MSDs risk factors include intensity, frequency and duration of the physical exposure. MSDs are also affected by individual factors, such as age, physical condition, sociocultural and psychosocial variables.
Type of Injuries
Back strain occurs when the muscle, ligaments and/or tendons in the back are damaged due to overstretching or overuse of the muscles in the back. These injuries result in strains, sprains and tears. Herniated disks are also a type of back injury found in workplace situations.
The most common causes of low-back pain are:
- Improper and/or excessive methods of lifting, pulling, pushing, carrying, holding, carrying or throwing an object (overexertion)
- Lowering, Bending or twisting
- Sudden slip or fall
- Cumulative trauma-multiple micro-injuries sustained over a period of time
To avoid workplace back injury, the implementation of an ergonomics program is recommended that focuses on redesign of the work environment and work tasks to reduce the hazards of lifting.
There are a number of proven ergonomic program components that can minimize back injuries on the job. These components include:
- Training in proper lifting techniques
- Physical conditioning and stretching
- Reduction in size of objects or material being moved
- Adjusting the height at which the object or materials are retrieved or deposited
- Implementing mechanical aids, such as hoists or adjusted lift tables to reduce the need to bend, reach and twist
- Evaluation of production, storage and display workflows to remove excessive reaching, bending, pushing, pulling, lifting loading and unloading
There are two methods for reducing sprains and strains in the workplace: design and work practice modification.
- By redesigning the workplace it might be possible to eliminate the lifting, pushing and pulling entirely by mechanical means. Examples: Use forklifts to move items, self-propelled or riding lawn mowers do not require pushing, and mechanical power to eliminate some pulling activities.
- Another design modification would be to change the size, shape and weight of the container. This has been done in many areas.
- Work stations, for workers who spend long hours in a standing or seated position, must be designed to reduce stress to the back and legs. A cushioned floor, a low footrest to enable workers to raise and lower their legs, and a work table of proper height are all important.
- Seated workers should be at a height comfortable for their work. Their knees should be slightly higher than their hips, and a footrest should be provided. The seat should provide support for the lower back. Finally, the work should be arranged to minimize stooping, excessive reaching and twisting at the waist.
Workers can modify their work practices in the following ways:
- Lift objects comfortably, not necessarily the quickest or easiest way.
- Lift, push, and pull with your legs, not your arms or back.
- When changing direction while moving an object, turn with your feet, not by twisting at the waist.
- Avoid lifting higher than your shoulder height. Use a step stool or ladder to move objects at these heights.
- When sitting, sit with your knees slightly higher than your hips, with a firm backrest for your lower back. Move, cross and uncross your legs frequently.
- Sit in a vehicle as you sit in a chair, with your knees slightly above your hips, with support for your lower back.
- When standing while working, stand straight. Avoid bending at your waist. For prolonged standing, use a low footstool for alternate resting of your legs and for altering your stance. Wear comfortable, supportive shoes.
- When walking, maintain an erect posture, wear slip-resistant, supportive shoes. Wearing quality work shoes with slip-resistant heels and soles can prevent the majority of slips, trips and falls.
- When carrying heavy objects, carry them close to the body and avoid carrying them in one hand.
- When heavy or bulky objects need to be moved, obtain help or use a mechanical aid such as a dolly, hand truck, forklift, etc.
- When stepping down from a height of more than eight inches, step down backwards, not forward.
There are numerous lifting theories and techniques, of which the "straight-back, lift-with-your- legs approach", is the most common and most frequently promoted. But after decades of promotion and training this approach to lifting has not been widely accepted by workers, and there is little or no evidence that it has reduced the number or severity of injuries.
In more recent years, numerous other theories and techniques have been promoted, criticized and discarded. There are hip flexing, kinetic-lifting, stooped-posture and pelvic-tilt techniques, among others, which all have both positive and negative considerations. Presently, however, there is no "one-best" lifting method for all lifts, for all people.
Basically, there are seven rules for safe lifting that have been developed over the years. Some of these are similar to rules of the past; others are new and different. They are presented below:
- Lift Comfortably. Choose the position that feels best, with or without a straight back.
- Avoid Unnecessary Bending. Do not place objects on the floor if they must be picked up again later.
- Avoid Unnecessary Twisting. Turn your feet, not your hips or shoulders. Leave enough room to shift your feet so as not to have to twist.
- Avoid Reaching Out. Handle heavy objects close to the body. Avoid a long reach to pick up an object.
- Avoid Excessive Weights. If the load is too heavy, get help or use a mechanical device, if possible.
- Lift Gradually. Lift slowly, smoothly and without jerking.
- Keep in Good Physical Shape. Get proper exercise and maintain a good diet.
Sprains, strains and lower back pain on the job can be partially caused by what you do or do not do at home. Below are some recommendations to follow.
- Maintain a reasonable weight, eat nutritious meals, and exercise to maintain well-conditioned muscles.
- Sleep on a firm mattress and avoid sleeping on your stomach. When sleeping on your side or back, bend your knees. Place a pillow under your head, another between or beneath your knees.
- When you awake, remember that your muscles are still at rest. Gradually stretch your leg, arm, back and stomach muscles before you get up. Do some more stretching exercises after you are out of bed. Some exercises for your consideration are provided in the section entitled, "Treatment of Lifting, Pushing, and Pulling Injuries." Early morning is the recommended time for these exercises, but any time of the day is all right. More important than the time of day is the development of a regular exercise program. This is particularly important for individuals who do limited physical work, but a regular exercise program is also valuable for individuals who are involved in heavy physical labor.
There is one final important rule: "THINK BEFORE YOU LIFT". It is better for workers to use their own common sense than to teach them specific lifting, pushing, pulling, walking, climbing or jumping procedures. This is not to imply that unsafe behaviors should not be pointed out to others and corrected. For example, "common sense" may tell certain people to jump down from heights of several feet. Certainly, when people exhibit this type of behavior or when they attempt to carry two hundred pounds, the errors of their behavior should be brought to their attention. Remember, you are the major cause of your injuries; therefore, you have the major responsibility for preventing them.
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