That means that 10 times more weight can be supported by a curved spine than if it were straight. That is why proper lifting is so important. If you bend at the waist to pick up a box you straighten out your lumbar spine. By losing a curve you cannot support as much weight and are therefore at risk for an injury. By bending at the knees and squatting down you are able to maintain your spinal curves and protect your back.
People sometimes complain that they have a 'slipped disc' in their back.
In reality, a disc can't slip out of place. But discs can be injured. An intervertebral disc is built like a jelly donut, it has a soft, jelly-like centre called a nucleus pulposus and a tough outer casing called the annulus fibrosis. The outer annulus is made of ligament and serves to join the vertebrae to one another while the jelly-like nucleus provides some cushioning for the spine. Sometimes the outer annulus can tear and this allows the inner jelly to leak out.