High cycling cadence reduces carbohydrate oxidation at given low intensity metabolic rate

Cycling cadence (RPM)-related differences in blood lactate concentration (BLC) increase with increasing exercise intensity, whilst corresponding divergences in oxygen uptake ([Formula: see text]O2) and carbon dioxide production ([Formula: see text]CO2) decrease. Aim of the present study was to test whether a higher RPM reduces the fraction (%) of the [Formula: see text]O2 used for carbohydrate oxidation (relCHO) at a given BLC. Eight males (23.9 ± 1.6 yrs; 177 ± 3 cm; 70.3 ± 3.4 kg) performed incremental load tests at 50 and 100 RPM. BLC, [Formula: see text]O2 and [Formula: see text]CO2 were measured. At respiratory exchange ratios (RER) < 1, relCHO were calculated and the constant determining 50 % relCHO (kCHO) was approximated as a function of the BLC. At submaximal workload [Formula: see text]O2, [Formula: see text]CO2, and relCHO were lower (all p < 0.002; η(2) > 0.209) at 50 than at 100 RPM. No differences were observed in [Formula: see text]O2peak (3.96 ± 0.22 vs. 4.00 ± 0.25 l · min (-1)) and RERpeak (1.18 ± 0.02 vs. 1.15 ± 0.02). BLC was lower (p < 0.001; η(2) = 0.680) at 50 than at 100 RPM irrespective of cycling intensity. At 50 RPM, kCHO (4.2 ± 1.4 (mmol · l (-1))(3)) was lower (p = 0.043; η(2) = 0.466) than at 100 RPM (5.9 ± 1.9 (mmol · l (-1))(3)). This difference in kCHO reflects a reduced CHO oxidation at a given BLC at 100 than at 50 RPM. At a low exercise intensity, a higher cycling cadence can substantially reduce the reliance on CHO at a given metabolic rate and/or BLC.