*3.5. Physiological and Metabolic Parameters at VO2max*

Maximal values of VO2, VO2/R, W, WR, HR and RER are presented in Table 3. Significant group differences in VO2MAX (15.9%, *p* = 0.002), VO2/RMAX (17.5%, *p* = 0.002), WMAX (23.8%, *p* < 0.001), WRMAX (25.8%, *p* < 0.001), and RERMAX (7.0%, *p* = 0.001), but not for HRMAX (*p* = 0.966) were found.

In VO2MAX, no correlation with any antioxidant marker was observed (Table 4).

#### **4. Discussion**

This study provides the first direct comparison of endogenous antioxidant, hematological, performance and metabolic biomarkers (VT1, VT2 and VO2MAX) between PRO and AMA cyclists. Our results demonstrate that: (i) PRO have higher values in MCH, MCHC, CAT, GSSG and GSSG/GSH but lower values in SOD than AMA; (ii) PRO have higher levels of absolute and relative power output and oxygen consumption in all intensity zones (VT1, VT2 and VO2MAX) than in AMA, with the largest differences found at VT1; (iii) inverse correlations were identified in WVT1, VO2VT1, WVT2 and VO2VT2 with GSSG/ GSH in PRO.
