High cycling cadence reduces carbohydrate oxidation at given low intensity metabolic rate
Journal Title: Biology of Sport - Year 2015, Vol 32, Issue 1
Abstract
Cycling cadence (RPM)-related differences in blood lactate concentration (BLC) increase with increasing exercise intensity, whilst corresponding divergences in oxygen uptake (VO[sub]2[/sub]) and carbon dioxde production (VCO[sub]2[/sub]) decrease. We tested the hypothesis, that a higher RPM reduces the fraction (%) of the VO[sub]2[/sub] 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, VO[sub]2[/sub] and VCO[sub]2[/sub] were measured. At respiratory exchange ratios (RER) <1, relCHO were calculated and the constant determining 50% relCHO (k[sub]CHO[/sub]) was approximated as a function of the BLC. At submaximal workload, VO[sub]2[/sub] and RER were lower (p<0.001) at 50 than at 100 RPM. No differences were observed in VO[sub]2peak[/sub] (3.96 +/- 0.22 vs. 4.00 +/ 0.25 l min[sup]-1[/sup]) and RER[sub]peak[/sub] (1.18 +/- 0.02 vs. 1.15 +/- 0.02). BLC was lower (p<0.001) at 50 than at 100 RPM irrespective of cycling intensity. At 50 RPM, k[sub]CHO[/sub] (4.2 +/- 1.4 (mmol l[sup]-1[/sup])[sup]3[/sup]) was lower (p<0.05) than at 100 RPM (5.9 +/- 1.9 (mmol l[sup]-1[/sup])[sup]3[/sup]). This difference in k[sub]CHO[/sub] 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.
Authors and Affiliations
Ralph Beneke, Ahmad Alkhatib
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