The subjects ran on a treadmill at 8 km/h and zero incline for 4 min. The speed was then increased by 0.5 km/h every 30 s until volitional exhaustion. O2 uptake (V̇O2), CO2 output (V̇CO2), and heart rate (HR) were continuously recorded on a breath-by-breath or beat-by-beat basis by means of a metabolic unit (K4b2, Cosmed, Italy) and by electrocardiogram (ECG; MDF VF, Esaote, Italy). This procedure allowed us to determine gas exchange threshold (GET) and maximal O2 consumption (V̇O2max), as from standard procedures