The festive season is celebrated by many with more than usual degrees of energy expenditure associated with holiday traveling. Traveling long distances involves sitting for long hours as the driver of a car or as a passenger in buses, trains or airplanes.
Sitting may induce posterior rotation of the pelvis, reduction of lumbar lordosis, and increases in muscle tension, which may be associated with low back pain. The combination of prolonged sitting in awkward positions or sitting slumped for prolonged periods, heavy or repetitive lifting of luggages, and whole body vibrations (dose and duration of exposure does matter, especially duration of exposure) can initiate pain in a person without back pain or aggravate the underlying pain in the patient already suffering from lower back pain.
The sitting position encourages the pelvis to rotate backwards, flattens the lumbar lordosis, increases muscle tension, disc pressure, and pressure on the ischium and coccyx. This increases the load on the spine and intervertebral discs. Sitting in a slumped position is known to increase disc pressure even more, and to aggravate chronic low back pain.
Sitting with the knees crossed can put tension on the sciatic nerve or compression of the peroneal nerves at the knee. Sitting with ankles crossed can compress the peroneal nerve at the ankle. Pressure on these nerves will manifest as tingling and numbness in the toes and feet and depending on the degree and duration of pressure, there can be weakness of muscles in the foot and ankle.
It has been shown that as the lumbar spine was loaded from the supine to the sitting position, the end-plate angles were decreased significantly. This decrease was worse as the spinal degeneration was increased. There were also significant changes in the anterior and middle disc heights between the supine and the sittingpostures irrespective of the degree of degeneration. In the study, the overall lumbar lordosis did not significantly change between the two postures1.
Using a fitted backrest during sitting that reduces the ischial load and maintains lumbar lordosis may help increase seating comfort and reduce low back pain. Performing pelvic tilts while in the sitting position are also helpful. Frequent weight shifts and getting up often to ambulate are necessary during long trips.
1. Karadimas EJ. Siddiqui M. Smith FW. Wardlaw D. Positional MRI changes in supine versus sitting postures in patients with degenerative lumbar spine. [Journal Article. Research Support, Non-U.S. Gov’t] Journal of Spinal Disorders & Techniques. 19(7):495-500, 2006 Oct.