The sciatic nerve is the largest and longest nerve in the body. Formed by a bundle of nerves in the lumbar spine, the nerve exits the spinal column at the lower back, runs through the hip and down the back of the leg to the sole of the foot. When the nerve becomes irritated or inflamed, it causes a condition known as sciatica--pain, tingling and numbness along the path of the nerve. Several factors contribute to sciatica, including a tight piriformis muscle and herniated discs. According to Spine Universe, many of the leading causes of sciatica may be caused by exercise.

Exercise and Piriformis Syndrome

The piriformis is a small muscle in the buttock, beneath the gluteus muscles. When the piriformis muscle becomes tight or inflamed, it irritates the sciatic nerve. The piriformis muscle rotates the leg outward and stabilizes the hip. Exercises that move the leg away from the midline of the body, such as side leg raises and the abductor machine, can cause tightness in the muscle. Weak inner thigh muscles can also contribute to the condition as the muscles on the outer thigh and buttock, such as the piriformis, have to work harder to stabilize the leg during exercise.

Exercise and Herniated Discs

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The spinal column has discs of cartilage between the bones which act as shock absorbers and cushioning between the bones. When a disc becomes herniated, it bulges out from the spinal column and, in severe cases, presses against the nerves that exit the spine. Herniated discs are commonly caused by improper lifting, such as using improper form during resistance training. Weak core muscles can also contribute to the condition as these muscles stabilize the spine during exercise.

Exercise and Isthmic Spondylolisthesis

Isthmic spondylolisthesis occurs when a vertebral bone slides forward and pinches the nerves in the spinal column, which can lead to sciatica. Spondylolisthesis has several causes one of which is stress fractures caused by heavy lifting. Weightlifters, gymnasts and football players often develop the condition due to excess stress on the spine.

Exercise and Degenerative Disc Disease

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Degenerative disc disease is an age-related condition where the discs between the vertebral bones wear down, which can irritate the spinal nerves and cause sciatica. Sports, daily activities and injuries are contributing factors. As with herniated discs, improper lifting, using improper form and core muscle weakness can all contribute to the disorder.

Conclusion

While exercise can cause sciatica, it can also help relieve the condition. Stretches that pull the leg across the midline of the body, and strengthen the inner thighs, can help prevent and relieve piriformis-related sciatica. Exercises that strengthen the abdominal and lower back muscles, such as Pilates, can help prevent sciatica from herniated discs and degenerative disc disease. Avoiding or reducing exercises that put excess stress on the spine can prevent the disorder. Using proper form and wearing back support, such as a weight belt, can also prevent sciatica.