Cineradiographic study of spine during cycling: Effects of changing the pedal unit position on the dorso-lumbar spine angle [Studio cineradiografico della colonna nell'attività ciclistica: Variazioni angolari del tratto di rachide dorso-lombare nelle modificazioni della posizione della pedaliera]

Purpose. Low back pain is a frequent pathology among bicyclists, probably due to unappropriate saddle position. This radiographic study was conducted to evaluate dorso-lumbar angular values in two different pedal unit positions; the first one in a bicycle frame type with pedals in front of the saddle axis and the second one with the pedals behind the saddle axis, in order to define the most physiological sitting position. Materials and methods. Ten voluntary healthy adults, ranging in age between 21 to 45 years, were randomly choosen among a group of cyclist not involved in competition and underwent serial fluoroscopic studies while cyclists sit on two different saddles of a prototype cyclette; dorso-lumbar angles at both different sitting positions were measured on film according to modified Lippmann-Cobb method using as reference the upper somatic limitant of the eleventh or twelth dorsal vertebra and the lower somatic limitant of the third lumbar vertebra. Results. Statistical analysis of the measured angles demonstrates that the differences between the dorso-lumbar spine angle in the different saddle positions are statistically significative with a coefficient correlation equals to 0.64015 and p>0.01; angular values are more physiological in the second position with pedal unit behind the saddle axis. Conclusions. The incidence and importance of low back pain in cyclists can be reduced with appropriate pedal unit position; the position with pedals behind the saddle axis permits more physiological spine angles in comparison with the classic one having the pedals in front of the saddle axis; this fact is due to a different pelvic position which coincides with lumbar angles.