These three rules are applicable to most lifting situations. Following them whenever possible will reduce the amount of stress the back must go through during activity. This in turn makes a person less likely to sustain a back injury even when it is occasionally necessary to break the rules (when there is no other choice).
Of course, there are a few exceptions to these three guidelines. The following provides a quick overview of other safe approaches to lifting.
This technique is very useful to avoid back injury when lifting out of a bin or picking small objects off the floor, such as a golf ball.
For this technique, the knees do not bend. One leg is allowed to come off the floor behind the lifter and acts as a counter balance. The opposite hip bends and the body becomes almost parallel to the floor, except for the leg bearing the person's weight. One arm reaches to pick up the object while the other is often hanging on a stationary object for support, such as a countertop or the top end of a golf club.
Although the chest does point down toward the floor, it is a safe technique since lifting the back leg allows the spine to stay straight and the counter balance offsets the strain on the back.
This method is especially helpful to avoid back injury when lifting a heavy object above the level of the waist. If done correctly, it looks like a controlled toss of the object. The lifter can keep moving towards the destination of the object and swing it up to the surface. The object is then allowed to come away from the body and the momentum will help raise it, requiring less effort by the lifter.
This approach is useful for picking an awkward object off the floor. In this case, the lifter can kneel behind the object and first lift it on to the bended knee. Now the lifter can either straighten out the back knee to propel forward, or push with the front knee to propel backwards, depending on where the object needs to be carried. The chest may point down when the back leg is straightened, but the back will remain straight.
Again, not every situation will allow a person to use proper body mechanics, but using them on a regular basis whenever possible does greatly reduce a chance of sustaining a back injury while lifting.