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Adaptation of the Lumbar Spine to Different Positions in Bicycle Racing

Usabiaga, Jaime, MD, PhD*; Crespo, Ricardo, MD*; Iza, Ion, MD*; Aramendi, José, MD, PhD; Terrados, Nicolas, MD, PhD; Poza, Juan-José, MD, PhD§

Diagnostic Assessment

Study Design. A radiologic and electromyographic study was done of the adaptation of the lumbar spine to high-performance cycling.

Objectives. To evaluate changes in the lumbar spine produced by different cycling positions on different types of bicycles used during competition.

Methods. Three professional cyclists were observed to evaluate changes in the lumbar spine. Radiographs were obtained of the different positions adopted by the cyclists during competition, and changes in the angles of the lumbar spine were measured. An electromyographic study was done of the abdominal, lumbar, and thoracic paravertebral muscles.

Results. The cyclists' positions involved a change from discal lordosis to kyphosis. To obtain a more aerodynamic position, the cyclists flexed the hip and made the pelvis horizontal without changing disc angles. The contraction of paravertebral lumbar muscles was proportional to pedalling intensity and decreased in more aerodynamic positions. The tone of the paravertebral thoracic muscles depended on the extent of cervical hyperextension. Abdominal muscles remained relaxed in all bicycle positions and with all pedalling intensities.

Conclusions. The changes observed could modify the normal biomechanics of the lumbar spine, but the overall mechanical load on the spine is reduced by shifting weight onto the upper limbs. The imbalance that occurs between the activity of flexor and extensor muscles could cause lumbar pain in persons without proper physical preparation.

From the *Traumatology Department, Nuestra Señora de Aránzazu Hospital, †O.N.C.E. Pro-cycling Team, Instituto Vasco de Educación Física, ‡O.N.C.E. Pro-cycling Team, Fundación Deportiva Municipal de Avilés, and the §Neurology Department, Nuestra Señora de Aránzazu Hospital, San Sebastián, Spain.

Acknowledgment date: April 12, 1996.

First revision date: September 11, 1996.

Acceptance date: March 1, 1997.

Device status category: 1.

Address reprint requests to: Prof. Dr. Jaime Usabiaga Zarranz; Servicio de Traumatología; Hospital Nuestra Señora de Aránzazu; Apartado 477, San Sebastián 20080; Spain

© Lippincott-Raven Publishers.