Effects of short-term training using SmartCranks on cycle work distribution and power output during cycling

Abstract

SmartCranks use a free running bearing to promote independent pedal work by each leg during cycling. This system is designed for training the upstroke phase during cycling. The effects of training with SmartCranks on the power output (PO) and on cycle work distribution at the anaerobic threshold and the maximum power level were examined. Twenty male, non-professional cyclists were randomly assigned into intervention and control group, training 5 weeks with SmartCranks and conventional cranks, respectively. Before and after the training period the subjects performed an incremental test to exhaustion. Lactate was measured to determine the individual anaerobic threshold (IAT) and forces at the pedal were recorded to quantify changes in the work distribution over the full revolution. We observed no significant statistical difference for peak power (PO; 333.3+/-32.8 W vs. 323.3+/-21.8 W) and PO at IAT (229.6+/-30.1 W vs. 222.7+/-25.2 W) for SmartCrank and control conditions, respectively (P>0.05). However, we did observe that work distribution in the downward phase was significantly reduced in the SmartCranks training group at peak PO (from 70.0+/-4.9% to 64.3+/-5.8%; P<0.05). Although the possible implications of the change in the work distribution of sectors are not known, for the success in cycling performance-indicated by the PO-training with the SmartCranks was not more advantageous than training with conventional bicycle cranks.

Cycling Efficiency and Performance Following Short-Term Training Using Uncoupled Cranks

“…Previous research has speculated whether training with uncoupled cranks might enhance cycling performance by positively influencing one or several of these parameters. 6,7 Luttrell and Potteiger 6 reported improvements in GE following 6 weeks of training with an uncoupled crank system but unfortunately did not include any measure of performance. A more recent study 7 found small changes in the work distribution through various phases of the crank cycle following uncoupled crank training, and suggested this as a potential mechanism for improved efficiency.…”

“…6,7 Luttrell and Potteiger 6 reported improvements in GE following 6 weeks of training with an uncoupled crank system but unfortunately did not include any measure of performance. A more recent study 7 found small changes in the work distribution through various phases of the crank cycle following uncoupled crank training, and suggested this as a potential mechanism for improved efficiency. However, these changes did not translate to improvements in PPO or work rate at LT, while GE and performance were not actually measured.…”

“…[4][5][6][7][8] Some literature suggests that using cycle crank systems that are not fixed at 180° 8 or training with cranks that are independent of each other (uncoupled) 6 will improve efficiency in moderately trained individuals. PowerCranks (PowerCranks, CA, USA) and SmartCranks (SmartCranks GmbH, Zug, Switzerland) are uncoupled cycling crank systems that make it necessary for each leg to apply force on the crank over the entire crank cycle.…”

“…6,7 Luttrell and Potteiger 6 reported significant improvements in gross efficiency in a group of recreational cyclists after 6 weeks of training using PowerCranks with no change in maximal aerobic power (Vo 2max ). In the more recent study, by Bohm et al, 7 five weeks of training with SmartCrank was reported to modestly alter the distribution of power output over the crank cycle by significantly reducing the work performed in the downward sector of the pedal revolution. This reduction in work was compensated for by increases in work performed during the other phases of the pedal action so as to have no impact on power output at either maximum or the individual anaerobic threshold compared with the control group.…”

Differences in Pedaling Technique in Cycling: A Cluster Analysis

“…During the propulsive phase of the crank cycle, cyclists have the option to produce the same power by applying large pedal force or by driving pedal forces to optimize effective force (i.e. force tangential to the crank) and crank torque, therefore increasing their pedalling effectiveness 27 . Although cyclists from Cluster #2 presented lower effective force than their counterparts, this was potentially due to lower total pedal force application, given the index of effectiveness (ratio between tangential and radial crank forces) did not differ between clusters.…”