Bicycle Design Influence on Lumbar Spinal Anatomy

The purpose of this study is to compare intervertebral foramen diameter in the lumbar spine in the neutral standing position to that of an appropriately fit recumbent bike, hybrid bike, and diamond racing frame. Single participant was used to obtain lateral radiographs of intervertebral foraminal diameters both standing and on three bicycle formats. Subject was placed on an appropriate fit recumbent bike, hybrid bike, and diamond racing bike. MSK radiologist was incorporated to standardize angling of x-ray beam and analysis of data collection. Images were analyzed on the Philips iSite PACS system including measurement of the lumbosacral angle and the cross sectional area (CSA) of the intervetebral foramina at L3-4, L4-5, and L5-S1. Cross sectional area measurements were recorded. Cross sectional area was lowest in standing at all measured disk levels. L5-S1 was smallest level in standing and on all bikes tested. Recumbent bike foraminal cross sectional area was lower than the other two tested bicycles at L4-5 and L5-S1.