Sagittal lumbar spine position during standing, walking, and running at various gradients.

CONTEXT: Motion in the lumbar spine during certain physical activities may exceed tissue homeostasis, leading to low back pain. Previous authors have assessed sagittal motion of the lumbar spine during walking; however, limited attention has been focused on changes in spine position with walking or running on different surface gradients. OBJECTIVE: To investigate lumbar spine sagittal position during standing, walking, and running on level, uphill, and downhill surfaces. DESIGN: Three by three and 2 x 3 (activity by gradient) within-subjects design with repeated measures on both factors. SETTING: Motion analysis laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty healthy women (age = 23.4 +/- 2.2 years, height = 141.5 +/- 7.5 cm, mass = 60.5 +/- 5.9 kg) with no history of low back pain or surgery or lower extremity impairments or surgery. INTERVENTION(S): Subjects stood motionless, walked at 1.3 m/s, and ran at 2.9 m/s on a treadmill under 3 conditions: level, uphill at 5 degrees, and downhill at 5 degrees. MAIN OUTCOME MEASURE(S): We measured lumbar spine position and total lumbar range of motion in the sagittal plane using an infrared motion analysis system, with markers affixed to the skin over the sacrum and thoracolumbar junction. RESULTS: The average lumbar spine position, for both walking and running, was smallest uphill and greatest downhill. On all 3 gradients, the sagittal range of motion (flexion-extension) was greater when running than when walking. CONCLUSIONS: For each of the surface gradients, the average lumbar spine position was greatest during standing, at an intermediate value during running, and smallest during walking. Changes in lumbar spine position corresponding to different activities and different surface gradients are important considerations when rehabilitating patients with lumbar spine conditions.