Mechanical efficiency of cycling with a new developed pedal-crank.
The mechanical efficiency of cycling with a new pedal-crank prototype (PP) was investigated during an incremental test on a stationary cycloergometer. The efficiency values were compared with those obtained, in the same experimental conditions and with the same subjects, by using a standard pedal-crank system (SP). The main feature of this prototype is that its pedal-crank length changes as a function of the crank angle being maximal during the pushing phase and minimal during the recovery one. This variability was expected to lead to a decrease in the energy requirement of cycling since, for any given thrust, the torque exerted by the pushing leg is increased while the counter-torque exerted by the contra-lateral one is decreased. Whereas no significant differences were found between the two pedal-cranks at low exercise intensities (w*=50-200 W), at 250-300 W the oxygen uptake (V*O2, W) was found to be significantly lower and the efficiency (eta=w*/V*O2) about 2% larger (p<0.05, Wilcoxon test) in the case of PP. Even if the measured difference in efficiency was rather small, it can be calculated that an athlete riding a bicycle equipped with the patented pedal-crank could improve his 1h record by about 1 km.
Zamparo
Paola
P
Dipartimento di Scienze e Tecnologie Biomediche, Università degli Studi di Udine, Piazzale Kolbe 4, 33100 Udine, Italy. p.zamparo@mmu.ac.uk
Minetti
Alberto
A
di Prampero
Pietro
P
D000328:Adult; D001642:Bicycling / Q000502:physiology*; D004867:Equipment Design; D005080:Exercise Test / Q000295:instrumentation* / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D007866:Leg / Q000502:physiology*; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D011786:Quality Control; D019415:Torque