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Hey! How's Your Trunk?

Axial skeleton on the human body
Figure 1

Located in the axial skeleton (figure 1) and in the center of the body, the bottom section of the vertebral column consists of lumbar vertebrae (figure 2). Because of Its large segments and ability to bear the weight of the upper body, the lower back generates powerful movements, controls balance, shapes various movements and postures.

Figure 2


What kind of limitations does the lower back have?

Movement within a single intervertebral junction is relatively small, but added across the entire vertebral column, those small movements create extraordinary movement (figure 3)! Including forward and backward bending, side bending to the right or left (figure 3).

Figure 3

While the lumbar region is recognized for its sturdiness, it is also well-known for its lack of mobility. All lumbar vertebrae account for a measly 5-7 degrees of axial rotation, approximately 20 degrees of lateral flexion and 55-70 degrees of flexion and extension of the sagittal plane. Anything past its limitation will result in hyperextension. Trauma from overstretching and overextending the lumber's capabilities is common in sports like baseball (figure 4), volleyball, basketball, or weightlifting and can result in lumbar spondylolysis.

Figure 4


What is Lumbar spondylolysis?

Lumbar spondylolysis (figure 5) is a painful spine condition. It's an issue with a section of the vertebrae called the pars interarticularis. This thin piece of bone connects the facet joints, which links the vertebrae directly above and below to form a working unit allowing movement of the spine. This condition may result from trauma or chronic repetitive loading and hyperextension. While such methods may lead to lumbar spondylolysis, some are born with the defect which puts an individual at higher risk for pars interarticularis (lumbar spondylolysis).

Figure 5


Who is most affected?

This often occurs in 13 to 14 year old athletes and overwhelmingly among boys.


Spondylolysis vs. spondylolisthesis

Spondylolysis and spondylolisthesis are related but not the same (figure 6). The stress fracture from spondylolysis may cause the vertebrae to slip out of place. This is known as spondylolisthesis.

Figure 6



The first choice for most is the more conservative treatment. When this form of treatment is chosen, the duration of rest differs, but often sports that stress the trunk may be recommended to cease for 3 to 6 months. Aching pain is treated with physical therapy. Once aching pain is relieved after a period of rest, stretching and basic exercises are allowed to restart.

Figure 7

Surgery is suggested for athletes who wish to persist in a sport competitively for a prolonged period of time, as it is resistant to conservative treatment. If the separation is highly unstable, spinal fusion may be performed (figure 7).



There are a couple of things to keep in mind when trying to reduce the strain on the lumbar spine (figure 8). It is important to ensure the range of motion while maintaining flexibility of the trunk and the hip joint muscles, and strengthen the trunk muscles. Attention needs to be given to the limitation of the range of motion in the hip joint. The lumbar spine may compensate for the movement if there is a limitation of hip joint extension. This compensation will add a lot of stress and baggage to your trunk and may contribute to the development of lumbar spondylolysis.

Figure 8

How well are you taking care of your trunk?

Don't worry...

Workout for you:

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