*2.3. Graded Exercise Tests*

To assess aerobic capacity, a GXT was performed on a cycle ergometer (Corival 400, Lode B.V., Groningen, The Netherlands). After a 5-min baseline resting period, a 2-min warm-up period (60 rpm, unloaded pedaling) was initiated, followed by incremental work (30 Watt increase for each 3 min) until exhaustion (i.e., progressive exercise to VO2max). Minute ventilation (VE), oxygen consumption (VO2), and carbonic dioxide production (VCO2) were measured for each breath by using a computer-based system (MasterScreen CPX, CareFusion, Franklin Lakes, NJ, USA). The criteria used to define VO2max were as follows: (i) the level of VO2 increased by < 2 mL/kg/min over at least 2 min; (ii) H exceeded its predicted maximum; (iii) the respiratory exchange ratio (RER) exceeded 1.2; and (iv) the venous lactate concentration was >8 mM, which was consistent with the guidelines of the American College of Sports Medicine for exercise testing [24]. Additionally, the ventilation threshold (VT) was determined when VE/VO2 increased without a corresponding increase in the VE-to-VCO2 ratio and when end-tidal PO2 increased without a decrease in end-tidal PCO2 or a deviation from linearity for VE.
