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Postural problems are very common today. Thanks to the sedentary lifestyles that are now considered “normal” for most people, we spend much of our time with our bodies fixed in unhealthy positions. For example, eight hours of sitting at a desk puts the low back discs and muscles in a less than ideal position. Many hours of using our smartphones puts our head and neck in a suboptimal position, resulting in the “text neck” epidemic (will be topic of an upcoming blog post). These positions cause us to forsake our natural center of gravity and can further affect the way we carry ourselves over time.

In fact, the key to reducing strain on all structures in the body is to generally place them in line with our center of gravity. Merriam-Webster defines “center of gravity” as the point at which the entire weight of a body may be thought of as centered so that if supported at this point the body would balance perfectly.

When we maintain ourselves in this balanced position, the least amount of effort is needed, and the least amount of force is placed on our tissues. This means that when viewed from the side, a gravity line should intersect the ear, shoulder, hip, knee, and ankle. When viewed from the front or back, you can draw a line right down the center of the body and both sides would look identical. The shoulders and pelvis are level.

Consider the Leaning Tower of Pisa. Now that it is leaning, there is much more strain on its foundation, and it will only relentlessly continue to bend until it fully fails, unless more is done to shore up its foundation. Actually, the tower has been leaning so long—almost 840 years now—that it’s tempting to believe it will never fall. But the truth is that ever since it first began to lean during construction (as the foundation settled unevenly in the soft soil), there have been hundreds of interventions to keep it from falling. These included building compensations on one side of the tower and numerous adjustments by engineers over the years. However, the sad reality remains that the 12th century masonry, which has absorbed hundreds of years of excess stress due to leaning, could crumble at any time and completely collapse the tower. Even a minor earthquake could spell its end despite these heroic efforts.

Building on a poor foundation (poor posture) can have similarly catastrophic results for the back. Scientists have studied the pressure as seen inside the disc of the low back when individuals stand in different positions. The results are astonishing because they demonstrate the tremendous difference— for better or for worse—that slight shifts in posture make.

Studies have been performed to assess the pressure within a disc during different postures.1,2 Compared to someone standing in a relaxed standing pose, a person who has even a slight bend in her back creates four and one half times more pressure inside the disc when she lifts a pre-defined weight. However, if she lifts correctly with her legs, the pressure decreases to just three times as much, and only twice as much if she holds the weight close to her body.

Maintaining a correct posture and lifting correctly dramatically reduce pressure on the discs of the spine. See the graph below:

Even without lifting anything, a simple forward bend results in two to two and a half times increase in the disc pressure. And if you are sitting in a forward slouched position, you are putting two and a half times more pressure on the disc than when you stand upright. In contrast, lying down causes only a 20 percent strain in the disc when compared to standing. This is why most back pain patients with disc abnormalities prefer to lie down when they are in a lot of pain.

So it’s clear that your center of gravity makes a big difference in terms of strain on your discs. By becoming more aware of these differences and choosing postures that reduce strain in your daily activities, you can make a significant difference to your back health. While your disc does have some ability to heal itself as we have seen, you can improve its chances of remaining healthy by limiting this type of stress due to poor postures.

Also, when we strain, we significantly increase disc pressure. In fact, a simple sneeze or cough creates twice as much pressure as when we are at rest. Over the years, I’ve met many patients who have recounted an onset of severe sciatica or who have developed a disc herniation after a simple sneeze while they were sitting in a poor posture. (An easy way to protect yourself: If you’re going to sneeze, make sure you’re not in an awkward posture and brace yourself.)

References:

1. Wilke, H. J., P. Neef, M. Caimi, T. Hoogland, and L. E. Claes. 1999. “New in vivo measurements of pressures in the intervertebral disc in daily life.” Spine (Phila Pa 1976) 24 (8):755-62.

2. Nachemson, A. L. 1981. “Disc pressure measurements.” Spine (Phila Pa 1976) 6 (1):93-7.