The reliability of cycling efficiency

Purpose: The aim of this experiment was to establish the reproducibility of gross efficiency (GE), delta efficiency (DE), and economy (EC) during a graded cycle ergometer test in seventeen male subjects. Methods: All subjects performed three identical exercise tests at a constant pedal cadence of 80 rpm on an electrically braked cycle ergometer. Energy expenditure was estimated from measures of oxygen uptake ((V) over dot O-2) and carbon dioxide production ((V) over dot CO2) by using stoichiometric equations. Results: The subjects characteristics were age 24 +/- 6 yr, body mass 74.6 +/- 6.9 kg, body fat 13.9 +/- 2.2%, and (V) over dot O-2max 61.9 +/- 2.4 mL.kg(-1).min(-1) (all means +/- SD). Average GE, DE, and EC for the three tests were 19.8 +/- 0.6%, 25.8 +/- 1.5%, and 5.0 +/- 0.1 kJ.L-1, respectively. The coefficients of variation (confidence limits) were GE 4.2 (3.2-6.4)%, DE 6.7 (5.0-10.0)%, and EC 3.3 (2.4-4.9)%. GE was significantly lower at 95 W and 130 W when compared with 165 W, 200 W, 235 W, 270 W, and 305 W. GE at 165 W was significantly lower (P <0.05) that GE at 235 W. A weak correlation (r = 0.491; P <0.05) was found between peak oxygen uptake ((V) over dot O-2peak) and GE, whereas no correlations were found between (V) over dot O-2max and DE or EC. Conclusion: We conclude that a graded exercise test with 3-min stages and 35-W increments is a method by which reproducible measurements of both GE and EC can be obtained, whereas measurements of DE seemed slightly more variable.