Seventeen young healthy physically active males (age 23 ±3 years; body mass (BM) 72.5 ±7.9 kg; height 178 ±4 cm, (mean ±SD)), not specifically trained in cycling, participated in this study. The subjects performed two cycling incremental tests at the pedalling rate of 60 rev·min–1. The first test, with the power output (PO) increases of 30 W every 3 min, was to determine the maximal oxygen uptake (V’O2max) and the power output (PO) at V’O2max, while the second test (series of 6 minutes bouts of increasing intensity) was to determine energy expenditure (EE (V’O2)), gross efficiency (GE (V’O2/PO)) and delta efficiency (DE(DV’O2/DPO)) during sub-lactate threshold (LT) PO. V’O2max was 3.79 ±0.40 L·min–1 and the PO at V’O2max was 288 ±27 W. In order to calculate GE and DE the V’O2 was expressed in W, by standard calculations. GE measured at 30 W, 60 W, 90 W and 120 W was 11.6 ±1.4%, 17.0 ±1.4%, 19.6 ±1.2% and 21.4 ±1.1%, respectively. DE was 29.8 ±1.9%. The subjects’ BM (range 59–87 kg) was positively correlated with V’O2 at rest (p<0.01) and with the intercept of the linear V’O2 vs. PO relationship (p<0.01), whereas no correlation was found between BM and the slope of V’O2 vs. PO. No correlation was found between BM and DE, whereas GE was negatively correlated with BM (p<0.01). GE was also negatively correlated with V’O2max and the PO at V’O2max (p<0.01). We conclude that: V’O2 at rest affects GE during moderate-intensity cycling and GE negatively corelates with V’O2max and the PO at V’O2max in young healthy men.
