The use of an eccentric chainring during an outdoor 1 km all-out cycling test.

This study assessed whether an eccentric chainring that increases crank arm length at the downstroke and decreases it during the upstroke improves performance in a track cycling event: the 1000m time trial. It also determined whether selected physical and physiological variables and the velocity profile are associated with eccentric chainring performance. Twelve cyclists performed an outdoor 1000m time trial on a 333m banked, cement-surfaced track using two different chainrings, round and eccentric, in randomised order. The important findings of this study were that (1) performance did not significantly differ between chainrings; (2) neither the physiological variables (lactate and heart rate) nor the velocity profile (lap times) were affected by use of the eccentric design; (3) when time was saved with the eccentric chainring, it was significantly correlated with estimated lower limb muscle volume (r=-0.605), circumference (r=-0.739), estimated calf muscle volume (r=-0.772) and cross-sectional area (r=-0.745). Moreover, estimated lower limb muscle volume (r=-0.703), estimated calf muscle volume (r=-0.772) and cross-sectional area (r=-0.871) significantly predicted performance with the eccentric chainring. The physical variables associated with eccentric chainring performance were muscle anthropometric parameters. We have interpreted our results cautiously and suggest that the subjects who had greater lower limb muscle volume and greater calf muscle volume, seem to have had a significant advantage in performing with the eccentric chainring. Further testing with track specialists performing at national or international level would be helpful to define the maximal possibilities of this chainring.