RE-EVALUATION OF MECHANICAL EFFICIENCY DURING BICYCLE PEDALLING / 体力科学

ABSTRACT

In order to re-evaluate the mechanical efficiency during bicycle pedalling the total mechanical work (internal work + external work) and the energy expenditure were determined on four adult males (20-21 years) . The subject worked on a Monark bicycle ergometer with 6 different loads (0-5kp) at a constant pedal frequency of 50rpm. The internal work (W-int) to accelerate the leg itself was determined by a cinematographic procedure used by Fenn (1930) . With the data of external work (W-ext) and energy expended above resting (E<SUB>t</SUB>-E<SUB>r</SUB>), the‘true’efficiency has been calculated as<BR>‘True’efficiency=W-int+W-ext/E<SUB>t</SUB>-E<SUB>r</SUB>×100<BR>The result obtained was as follows 1) The time course of kinetic energy due to leg movement was similar to those in walking and running reported previously. 2) The W-int at 0kp ranged in about 70-90kgm/min. In the mean values of four subjects the W-int tend to be constant at the loads from 0 to 3kp (about 80kgm/min), but increased appreciably at higher loads of 4-5k p (about 100-110kgm/min) . 3) The ratios of W-int to W-ext were about 20-30% at lkp, 10-20% at 2kp and 5-10% at 3-5kp. 4) The efficiency of leg movement only at Okp resulted in high values of about 40-85%, suggesting energy transfer between leg and inertia wheel. 5) The efficiency values at 1 to 5kp, ranging in 23.5-36.2%, appeared to show a maximum at intermediate work loads. 6) The‘true’efficiency so calculated did not largely differ from the efficiency calculated by conventional way ; 1.5-4% higher than the work efficiency, 2-5% higher than the net efficiency, and 3-5% higher than the apparent efficiency at intermediate loads.