The conventional wisdom of safe lifting isn't supported by research.
The long standing "wisdom" of "lift with your legs, not your back" may not be so wise. Before we get into the good stuff, let me first start by bashing on my own kind. Around 75% of physical therapists believe that lifting with your legs, not your back is a safe way to avoid injury. It has been drilled into therapists and the public as a way to protect your back. There is one fatal flaw however, it is NOT true. Lets take a minute to examine the research.
There is one thing that can be agreed upon and supported by the evidence; which is to keep the load you are lifting closer to your body. This decreases the lever arm and demand on your spine. However, whether you decide to stoop and lift vs bend the knees and lift has surprisingly little impact on the forces through the spine. Being taught to "lift properly" doesn't really change injury outcome and can often increase the chance of injury because we are trying to isolate body parts vs using the system as a whole. Protecting the back was the driving force for teaching proper lifting technique. This was based on a false idea that the back is a fragile system. In fact, the back is a very tough, resilient structure.
Now you may be thinking to yourself that stooping to lift places more load on the spine. That at least makes sense superficially. These forces have been measured using implanted devices called vertebral body replacements. They actually implant them in the spine to measure the forces experienced during activity. The differences in forces with all types of lifting, whether "properly" or other method yielded negligible results. That is correct, there is not a significant change in load on the vertebrae with different methods of lifting. With that in mind lets look at a few studies that examine injury occurrences with lifting in the work place. Several well designed studies and meta analysis from 2010-2016 found the following:
- There is little to no evidence between stooping repeatedly and back pain.
- It is almost impossible to prevent spine flexion when lifting. (using any method)
- More time being spent flexed forward past 30 degrees actually was linked to lower back pain.
- Heavy lifting is not linked to increased back pain.
- People that wear back braces to "protect" a healthy spine in the workplace actually have a higher incidence of back pain
- Changing lifting technique doesn't actually change the forces transmitted through the spine.
What does all of this mean? Well it doesn't mean that you should go try to lift several hundred pounds with horrible form or without building up strength to get to that point. But it does mean that you shouldn't be overly concerned about protecting your back when doing chores around the home or in the yard. Yes, there are exceptions to this; recent surgery, structural damage or injury to name a few. For the majority of us, we shouldn't be concerned about general lifting technique. Keep the weight in close and do what comes naturally.