According to Travelers Insurance, the most common cause of accidents and injuries is Material Handling. It wouldn’t be much of a stretch to believe that many of these could very well be back injuries resulting from overexertion as the result of manual lifting.
Many times we simply don’t think before we lift something, putting ourselves at risk for an overexertion injury.
The human back is actually fragile, depending on its muscles for protection from injury. Once injured, a back is at greater risk for future injury if we fail to protect it by practicing good lifting technique.
How can we reduce such overexertion injuries, especially those involving the back? Some effective approaches include:
- Training employees in safe lifting techniques
- Highlighting the dangers of lifting improperly
- Setting single-person lifting limits
- Constant reminders and supervisory oversight
- Stretching exercises at the start of a work shift
- Using lifting aids whenever possible
NIOSH guidelines on manual lifting were prompted by Department of Labor and National Safety Council data, which indicated that back injuries and overexertion account for 20 – 30% of all workplace injuries. Liberty Mutual data(1) indicate that injuries caused by overexertion account for over 30% of all non-fatal work-related injuries.
Given this information, it’s not unreasonable to expect that many of us might be candidates for a back injury if we don’t use effective lifting techniques, both on and off the job.
NIOSH developed the “Lifting Equation”(2) that allows us to calculate the maximum safe weight (Recommended Weight Limit, or, RWL) for any single-person manual lifting activity performed over the course of an 8-hour shift. Lifting any weight greater than the RWL for an extended time period can increase the risk of injury.
The NIOSH recommended weight limit for a single-person two-handed lift is 51pounds, under the best of conditions. A number of factors can contribute to lowering this weight limit, i.e.:
- How far away from the body is the object carried?
- How high off the floor is the object being carried?
- The height difference between the object’s origin and its destination?
- How much the body is twisted to accomplish the task?
- How many lifts are to be completed in a given period of time?
- How well can the object be grasped?
The Lifting Equation can be used to calculate the safe weight limit for any given repetitive lifting operation, or, we can simply keep the following precautions in mind, when lifting requirements vary over a workday.
- Designate a weight limit beyond which tasks are designated as 2-person lifts
- Get a good grip on the load
- Keep the object as close to the body as possible (reaching out puts added stress on the back)
- Carry the object with the elbows as close to 90-degrees as possible
- Don’t twist the body while carrying the object
In addition, the following can help to reduce the stresses involved in manual lifting:
- Use hoists, conveyer tables or lift trucks
- Get help to lift heavy or cumbersome loads
- Minimize lifting motions below the knees and above the shoulders
- Store most-used items in the power zone, between standing knuckle height and shoulder height
- Most importantly, always use good lifting technique
Good lifting technique doesn’t come naturally and takes practice in order make it a part of any lifting routine. The critical component, “lift with your legs, not with your back” plays an important role when you lift. It’s your muscles that provide the strength for lifting, and your legs contain some of the strongest muscles in the body, far stronger than back muscles.
The following are suggestions that can help you to lift while minimizing the risk to your back.
- Check the weight of the object to determine if you can handle it. Try to lift one edge before grabbing the object. Many people find objects weighing less than 51 pounds to be too heavy for them. If in doubt, get help.
- Make sure that there is a clear path to your destination.
- If the object is on the floor or on a low surface, I have found the following to be effective:
- Take a shoulder-wide stance close to and directly in front of the object to be lifted.
- Bend your knees.
- Look straight ahead, and lean slightly backward, as if you were preparing to sit down (this will serve to straighten your back).
- Keep your back straight (you want to lift with your legs, not with your back).
- Get a good grip (opposite corners of a box). Punch out finger holes on boxes that can’t be easily gripped.
- Lift by straightening your legs in a smooth movement.
- Never twist your body while holding a load. Turn your whole body.
It takes practice to make safe lifting a habit. With practice, these suggestions can help reduce the risk of a common injury.
- Liberty Mutual 2018 Workplace Safety Index
- Application Manual for the Revised NIOSH Lifting Equation, NIOSH Pub #94-110
Joseph Werbicki is a Safety Consultant, Trainer and Author. His articles have appeared in Occupational Health & Safety, EHS Today, and newsletters of the Boston, Springfield (MA) and Worcester (MA) ASSE chapters. Contact him at firstname.lastname@example.org for a copy of his Executive Summary introduction to his comprehensive safety training program.