Introduction/Purpose: An understanding of normal pelvic motion during seated cycling is relevant to saddle design and bicycle fitting. In this study, we investigated the effects of gender, power, and hand position on pelvic motion throughout a pedal stroke. We also investigated whether anthropometric factors could explain any interindividual differences observed.
Methods: Twelve experienced male and 14 experienced female cyclists participated. Each subject was custom fitted to a stationary bicycle and then rode the bicycle at three power outputs (100, 150, and 200 W), with their hands in the tops and drops position. The kinematics of a triad of motion-capture markers, located on posterior pelvic landmarks, were used to characterize pelvic motion.
Results: The largest angular excursions were observed in the nonsagittal planes, with the pelvis rotating internally (~3°) and rolling laterally (~2°) toward the downstroke. These pelvic rotations caused the hip on the downstroke side to translate anteriorly and inferiorly. Compared with males, females exhibited greater average anterior pelvic tilt in the drops hand position (males: 21 ± 3°; females: 24 ± 4°; P = 0.036). Interindividual differences in pelvic motion could not be independently explained by measures of ischial tuberosity width or hamstring flexibility. However, average anterior pelvic tilt was negatively correlated with lumbar flexibility among the males (r = 0.75; P = 0.024), suggesting that this may be an important factor to consider in bicycle fitting.
Conclusions: We observed substantial pelvic motion during seated cycling, with experienced female road cyclists exhibiting greater average anterior tilt than their male counterparts. Pelvic motion seems to arise naturally during seated cycling and should be considered when designing saddles and establishing bicycle-fitting procedures.
Departments of 1Biomedical Engineering, 2Mechanical Engineering, and 3Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI
Address for correspondence: Heidi Ploeg, Ph.D., Department of Mechanical Engineering, 1513 University Ave., Madison, WI 53706; E-mail: email@example.com.
Submitted for publication December 2006.
Accepted for publication July 2007.