REAL-TIME FEEDBACK OF PEDAL FORCES FOR THE OPTIMIZATION OF PEDALING TECHNIQUE IN COMPETITIVE CYCLING

INTRODUCTION: It seems doubtful that performance in road cycling can be improved by increasing the amount or intensity of training. Competitive cyclists already ride between 35,000 - 50,000 km per year as it is, the average daily time spent in the saddle being around 6 hours. An alternative means of increasing performance is to refine pedaling technique, so that a greater proportion of the energy used goes into forward propulsion. The same amount of energy is expended whilst riding speed is increased, or the amount of energy expended is reduced whilst retaining the same speed. METHODS: The pedal forces are measured by triple-axis piezo force measuring elements, which can be integrated into LOOK-compatible cycle pedals. Crank angle and pedal angle are measured by special potentiometers. All measured variables are transmitted on-line to a PC for further processing. Speeds and angles of incline can be set on the treadmill used in the test. A computer monitor displays the feedback signal in real-time, whereby either the tangential force, the radial force or efficiency at that moment, i.e., the ratio between tangential force and that resulting, can be presented. Twelve competition cyclists took part in the tests. Each trial, at a rate of 200W and a pedaling frequency of 60 rpm, lasted 30 minutes and was broken down into three 10-minute periods. No feedback was given during the first 5 minutes, one of the respective parameters mentioned above was given as feedback in the second 5 minute period. RESULTS: Comparing the phases without feedback to the three periods with feedback, efficiency of pedaling action increases significantly from 50% to 60%. A differentiated view emerges when one compares the effect of feedback in the various sectors of the crank circle and in relation to the various feedback parameters. In the area of the lower dead-point and during the pull-up phase, efficiency was raised on average over the three parameters by a significant 15% and 62% respectively. Feedback of radial forces produced the smallest improvement. CONCLUSIONS: Refinement of pedaling technique with regard to higher efficiency of forward propulsion using the means of visual feedback in real-time promises improved results. The sports cyclists who took part in the tests were unanimous in believing that the feedback on pedal forces gave them fresh insight into their pedaling action. Requests were made for the regular use of feedback during training sessions. One could mention the development of a technique model in competitive cycling as another possible use of feedback. In this case, however, it would be necessary to consider overall energy efficiency at the same time. A further requirement is that the athlete’s muscular system can adapt to the new training conditions