Is lifting with a straight back safer than lifting with a rounded back?
Updated: Sep 1, 2020
I couldn’t wait to talk about this topic of proper lifting because there has been a buzz of controversy around it in the physical therapy peer-reviewed journals for some time. The myth-busting study, published in the Journal of Orthopaedic and Sports Physical Therapy last November, was led by researchers from Curtin University in Perth, Western Australia. The team of researchers performed a systematic review with meta-analysis. What that means is they scanned all the top-quality studies specifically on the topic and reviewed them looking for conclusive evidence to support a claim. In this case, the researchers found, “There is no evidence that lifting with a flexed or round back increases your risk of back pain,” said Professor O’ Sullivan.
Therefore, there is not enough evidence to say that lifting with a straight back is safe or the best way to lift. Strange, because this has been the advice of healthcare providers for decades. So how did this all start? Straight back lifting was traced back to a study published in 1963 by a famous medical doctor and researcher from Sweden, Alf Nachemson. Back in the early '60s, biomechanics of the spine was still a mystery. Nachemson took spinal vertebrae and discs from fresh cadavers and stuck them in a pneumatic vice, so he could measure pressure in the discs as he increased the weight. His work demonstrated that if you tilted the angle of the vice-like a spine bending forwards and backward – the pressure on the spinal discs at these extreme positions increased by up to six times. He concluded that was the cause of disc ruptures, and the concept of a flexed spine under load can cause back pain, and therefore, we should avoid it. This concept was further supported in the '80s and '90s when researchers stuck needles in the discs of volunteers, and the increased disc pressure replicated Nachemson's theory. We jumped onto this theory because it made sense in the laboratory, but it wasn't a live person — a moving spine with so many other systems working together.
1960’s poster adapted from Alf Nachemson’s research depicting the intradiscal pressure in the lumbar spine in various postures. The theory was to avoid these postures if you had back pain. It was commonly taught in physical therapy schools around the world to warn us of the dangers to our low backs from repeated bending and sitting.
More recent studies started finding faults in the theory. In 2008, the British Medical Journal published a review of studies examining people who lifted heavy loads for a job – such as baggage handlers and postal workers. All 17,000 participants were taught to lift with a straight back, and none of them demonstrated any benefits form the advice.
Researchers also looked at athletes that lifted and produced heavy loads to the spine in flexion – such as weightlifters and rowers and found no evidence that repeated flexing the spine over time causes back pain.
“Fracturing a spine in a vice is not that applicable to human lifting studies,” says Professor Nic Saraceni.
Our back is a brilliantly made structure. It can twist and turn in such impressive contortions, lift heavy objects, aide in throwing and kicking balls with precision and speed. There is no machine capable of doing what our spine can do. The anatomical studies of our spine have given us a great deal of information and have shed light on why we can bend over at the waist and pick up a heavy object repeatedly and not injure our spine. I want to take you back to a fun child’s toy you may have played with as a kid, the Chinese finger trap. Remember that narrow woven bamboo cylinder that you would put your index fingers inside, and as you pulled them apart, they became trapped. That woven material tightening around your fingers is how our low back fascia (the connective tissue) woven around the back muscles and spine structures holds everything together when we flex and lift. This fascia is so strong because it has the same biomechanical properties as the chines finger trap. Try pulling your finger out, you can't, and the harder you pull, the tighter the bamboo squeezes your finger. Our fascia functions the same way.
We must train our muscles, fascia, ligaments, and those small joints in the back to lift heavy objects.
So, what is the best way to lift things? The evidence doesn't give us a simple answer here, but what we know is this, do not rush, gradually build up to lifting heavy objects, and keep them close to your body when carrying them. It would help if you also looked for safer alternatives to moving heavy objects like hand trucks, carts, and dollies.
Lastly, stay flexible, loose, and warm up your body before spending time lifting a heavy object. Take adequate breaks and break up the job into smaller pieces of time. Our body adapts to consistent, progressively more challenging loads. We tend to see injuries when we violate that principle, doing too much load at once. Don’t split and stack a cord of wood in one day if you haven’t done it since last year.
In the Strongman Competition, athletes are required to perform many lifts of heavy objects from the ground. Here, Andy Deck is doing the "Tire Flip." Note his spine is flexed with a maximal bend in his ankles, knees, and hips to accomplish the task.
Lifting heavy object with a straight back as shown above does not prevent injuries to the low back.
Lifting heavy objects with a flexed or rounded back is the preferred method. This allows for the load to be distributed throughout the entire body. Here in this picture one can see that the load is distributed across the ankles, knees, hips, entire spine and then the arms. The power of the lift occurs primarily from the gluteal and leg muscles with the back muscles and its connective tissue creating great tension for support.