Biomarker Changes in Oxygen Metabolism, Acid-Base Status, and Performance after the Off-Season in Well-Trained Cyclists

Abstract

During the off-season, cyclists reduce their volume and intensity of training in order to recover the body from the high workload during the competitive season. Some studies have examined the effects of the off-season on cardiovascular, metabolic, and performance levels but have not evaluated oxygen metabolism, acid-base status, and electrolytes in cyclists. Therefore, our main objective was to analyze these markers in the off-season period (8 weeks) via finger capillary blood gasometry in well-trained cyclists. We found an increase in oxygen saturation (sO2) and oxyhemoglobin (O2Hb) (p ≤ 0.05) and a decrease in fat oxidation at maximum fat oxidation (FatMax) (p ≤ 0.05). In addition, we observed a decreasing trend of VO2 in the ventilatory threshold 2 (VT2) and maximum oxygen consumption (VO2MAX) (p ≤ 0.06) after the off-season in well-trained cyclists. Negative correlations were found between the pre–post off-season differences in the VO2 at ΔFatMax and ΔHCO3− (bicarbonate ion) and between power generated at the ΔeFTP (functional power threshold) and the ΔVO2MAX with the pH (r ≥ −0.446; p ≤ 0.05). After the off-season period, well-trained cyclists had increased markers of oxygen metabolism, decreased fat oxidation at low exercise intensities, and decreased VO2 at the VT2 and VO2MAX. Relationships were found between changes in the ΔeFTP and VO2MAX with changes in the pH and between the pH and HCO3− with changes in La−.