University of Montana, Maureen and Mike Mansfield Library
Abstract
Previous research has evaluated the Rotor crank system on indices of endurance performance (e.g. peak power output, VO2max, lactate threshold, onset of blood lactate accumulation, economy, delta, and gross efficiency) under laboratory conditions. However, previous research has not attempted to determine whether the use of the Rotor cranks can improve sustainable power output during a time trial. The purpose of this study was to investigate the effect of the Rotor crank system on 16.1km time trial performance in the field. Eleven recreationally trained cyclists (7 male, 4 female; age 21±2 yrs) volunteered to participate in the study. On two separate days, each subject performed two 16.1 km time trials (i.e. one Rotor crank (RC) and one normal crank (NC)) each day. Crank arm length was 175mm for both systems. Each time trial was preceded by a 15-minute familiarization period. The trial order was randomly selected and a crossover design was used. Thirty minutes separated each trial, which included a five minute active cool-down, ten minutes of bicycle preparation and fifteen minutes of cycling to familiarize the subjects with the new crank system. Mean power (watt), heart rate (HR), cadence, and time to completion (minutes) were recorded using the Cyclops PowerTap Pro (Madison, WI, USA). The data was averaged for each subject’s two RC and NC trials. A two-tailed dependent t-test was used to analyze differences between the RC and NC systems for the measured variables. There were no significant differences (p\u3c0.05) between the two crank systems. Finish times were 30.04 ± 1.5 and 29.77 ± 1.7 for the RC and NC, respectively. Similarly, mean power output was 226.63 ± 39.1 and 230.21 ± 37.3 for the RC and NC, respectively. There were also no significant differences in average cadence and HR for the trials. The theoretical improvement in cycling efficiency by eliminating the dead spot of the pedal stroke did not translate into an improvement in cycling performance during 16.1km time trial cycling
