Abstract des Autors

Most studies have shown that the pedaling speed at which peak efficiency is reached is generally lower than the one spontaneously chosen by cyclists and it can vary from 50 to 60 rpm. This research intends to determine the individual optimal pedaling rate expressing the maximum power by resorting to the aerobic mechanism as a source of energy. The study has been carried out on 14 professional cyclists who had been exercising for more than 5 years, split into two groups: 7 racing cyclists (STR) and 7 mountain-bikers (MTB). Tests have been made in a lab by means of a bicycle ergometer working both on constant power and heart rate (HR), i.e. after setting HR value the load automatically varies to keep HR constant. First of all, by means of a test with increasing loads (4 watt every 15 seconds) up to exhaustion, we have determined the maximum power output (Pmax), the pedaling rate set by the athlete (RPMmax), and the deflection point at which the linearity of the power output-HR relationship is lost (Conconi's modified test). The deflection point has been found to coincide with the last pair of value of the regression line corresponding to the highest correlation coefficient, among all lines obtained after progressively adding pairs of values to reach the maximum load. After discovering the HR corresponding to the deflection point, this has been reduced by 3% to find the HR at which each athlete would have exercised at different cycling cadences (from 70 to 100 rpm). This allowed settling the maximum power reached (Popt) and the related pedaling rate (RPMopt) while exercising at constant HR for 5 minutes. The results show that there is no significant statistical difference between the two groups of athletes as far their age, weight, height, HR corresponding to Pmax, deflection HR, mmol/I blood lactate at the end of tests at constant pedaling rate (2.19+/-0.6 mmol/l in STR and 2.50+/-0.7 mmol/l in MTB). Even the RPMmax determined by the athletes has not proven to be significantly different in STR (90+/-9.6 mm) and MTB (86+/-10.4 rpm). On the contrary, Pmax deriving from Conconi's modified test proved to be significantly higher in STR (331+/-25.8 watt) than in MTB (283+/-31.5 mm) as well as Popt at a constant heart rate (262+/-26 versus 293+/-41 watt) and related RPMopt (87+/-9.1 versus 72+/-8 rpm). The correlation between RPMopt and Popt was statistically significant (r=0.875) if considering all the athletes involved in the study. Hence, the optimal cycling cadence to obtain maximum power in aerobic condition is lower than the one preferred by cyclists and it depends on the power itself rather than the sport practiced. Verf.-Referat