Lower Back Stability: Fact and Fiction
Stability is a popular term these days when talking about the lower back and associated pain or injury. But what does stability really mean and how is it achieved?
Studies on human cadaver spines with the muscles removed have shown that the spine will buckle under a load of about 20 pounds. That’s all a spine can withstand without any supporting muscles! Muscles serve as guy wires to make sure the spine has enough stability to withstand loading and sustain postures and movement. The muscles don’t necessarily need to have high tension, the tension just needs to be of roughly equal magnitude at different levels and in different directions.
A big misunderstanding today is that spine stability can be improved through types of exercise where someone attempts to knock you off balance (for example, prodding you while you are standing on one foot). These techniques promote whole-body stability, which involves your center of gravity in the context of falling over. They are not specific to increasing spinal musculature stability.
To achieve spinal stability, one needs to increase muscular “stiffness”, which is analogous to how increasing the stiffness of supporting cables would increase the stability of the supported structure, like a bridge. Increased “stiffness”, as long as it is balanced, increases the ability of the spine to support heavier loads without getting injured. Balance is critical, because if one side is stiffer than the other, that will actually cause a decreased ability to withstand compressive loads.
The key to choosing stabilization exercises to help with lower back pain or simply to prevent injury is to select ones that put the lowest load on the spine. The following is a list of some common abdominal exercises, in order from lowest to highest compressive load on the lower back.
- Bent-leg raise
- Sit-up, feet unanchored
- Sit-up, feet anchored
- Straight-leg raise
- Isometric side bridge/plank
- Hanging straight-leg raise
- Hanging bent-leg raise
- Bent-leg sit-up
- Straight-leg sit-up