Not too many people put much thought into the various factors involved in lifting and the potential for back pain.
Most simply move to complete what ever lifting task is required whether it is lifting a child at home or a box at work.
But, the Revised National Institute for Health and Occupational Safety and Health Lifting Equation (RNLE), which is based upon the assumed estimate that the average worker can safely lift a 51 lbs load in ideal conditions, provides some good information to consider:
1. How far away from the body that an object is held
Obviously, objects held closer to the body require less lifting force and are easy to carry. If there is any doubt of this, try holding a squirming toddler out in front of yourself at arms length, and then, compare to when holding them close and tight.
2. The location of the object at the start of the lift and where it is finally placed
An object lifted and carried from counter height is less stressful than having to pick an object up from off the floor. Likewise, placement of the object on a counter surface is less stressful than having to place the object on the ground, or out front above the head (such as in a cupboard or closet shelf).
3. Distance traveled with the load
A load carried for a longer period requires more muscular effort and places more mechanical stress on the body. The capacity for lift actually will diminish over time which increases the risk of injury and back pain.
4. Frequency/Duration of lifting
Classified into 3 categories:
1) short- lifting for 1 hour or less followed by rest period of at least 1.2 times the duration of lifting
2) moderate- lifting for 2 hours or less followed by a rest period of at least 0.3 times the duration of lifting
3) long- lifting for between 2 hours and 8 hours with standard industrial rest periods
5. Hand-load coupling
Hand-load coupling involves the interaction of the hands in maintaining the load being lifted. Intrinsic muscles of the hand are small and will fatigue faster than larger muscle groups. Compensatory mechanisms employed to continue carrying the load, despite fatigue, can lead to injury.
6. and, Asymmetry or twisting of the spine while performing the lift or the carry
Asymmetry of carry, and lifting while twisted, are perhaps the leading causes of spinal disc injury and back pain. Quite simply, the supporting structures of the spine and discs are not designed to resist such unnatural forces. While in asymmetrical or twisted positions, the mechanical forces either displace internal loads towards the weakest areas of the body, or cause structures to perform tasks that they were not designed to do.
Therefore, in less than ideal lifting situations, such as with an awkward load, in reference to the 6 items above, or with weights exceeding 51 lbs, there is an increased risk of injury and back pain.
All lifting activities, whether at home or at work, should be engaged with the above concepts in mind in order to protect yourself from serious injury and back pain.
