3.2. Experimental Setting
The urine samples of seven volunteers were collected to determinate the urinary metabolomic profile correlated to physical activity and the consumption of 200 mL of red beetroot juice (RBJ). The experiment was carried out in three different experimental sessions (A, B, and C), with a common controlled food intake at breakfast.The exercise consisted of 3 min of warm-up at 30 W, followed by 30 min of aerobic exercise at constant workload at the individual pre-assessed VT1 (see Materials and Methods section). The subjects maintained pedal rates between 70–80 rpm. The volunteers were randomly numerated from 1 to 10 and divided into three groups (group 1: numbers 1, 3; group 2: numbers 4, 7; group 3: numbers 8, 9, 10) and alternatively assigned to the three experimental sessions with one week of wash-out. For each subject, five samples of urine were collected on each day at different times: first urine in the morning at fast (T0), one hour before exercise or rest (T1), and 120 min (T2), 180 min (T3), and 240 min (T4) after drinking the juice or placebo (