Pedaling Technique and Energy Cost in Cycling
Stig Leirdal and Gertjan Ettema
Pedaling Technique and Energy Cost in Cycling. Med. Sci. Sports Exerc., Vol. 43, No. 4, pp. 701–705,
2011. Purpose: Because cycling is an extreme endurance sport, energy saving and therefore efficiency is of importance for performance. It is generally believed that gross efficiency (GE) is affected by pedaling technique. A measurement of pedaling technique has traditionally been done using force effectiveness ratio (FE; ratio of effective force and total force). The aim of the present study was to investigate the relationship among GE, FE, and a new technique parameter, dead center (DC) size in competitive cyclists. Method: Twenty-one competitive cyclists cycled for 10 min at approximately 80% V˙ O2max at a freely chosen cadence (FCC). GE, FE ratio, and DC size were calculated from oxygen consumption and propulsive force recordings. Results: Mean work rate was 279 W,
mean FCC was 93.1 rpm, and mean GE was 21.7%. FE was 0.47 and 0.79 after correction for inertial forces; DC was 27.3% and 25.7%,
respectively. DC size correlated better with GE (r = 0.75) than with the FE ratio (r = 0.50). Multiple regressions revealed that DC size was the only significant (P = 0.001) predictor for GE. Interestingly, DC size and FE ratio did not correlate with each other. Conclusions: DC size is a pedaling technique parameter that is closely related to energy consumption. To generate power evenly around the whole pedal, revolution may be an important energy-saving trait.
COMMENT: A great study in experienced competitive cyclists to counter the "pedaling technique doesn't matter, just push harder" crowd. Leirdal and Ettema looked at a different metric, the "dead center" force, the minimal net force of the two cranks together usually seen when the cranks are perpendicular to the ground or at Top and/or Bottom "dead center". Using this metric they were able to correlate cycling efficiency to how small or large the force was here — with a chance of this study being wrong of less than 1 in 1,000. This is the first study that I know of that shows that a metric such as the CompuTrainer SpinScan has some real utility because SpinScan actually measures this DC torque. Of course, this also supports the PowerCranks as a training tool because the one thing we have been definitely been shown to improve is the torque across the top and bottom of the stroke (see below). PowerCrankers typically see an improvement in the "SpinScan" number of about 10 points.
Despite what the "just push harder" crowd says, pedaling technique matters. We disagree somewhat with their analysis of why this change occurs but the fact remains, it does occur.