The Acute Effect of In Natura Beetroot Juice Intake on Intra-Session Exercise Sequences During Concurrent Training

The purpose of this study was to analyze the acute effects of in natura beetroot juice intake on intra-session exercise sequences during concurrent training. Following a randomized double-blind placebo-controlled crossover design, 20 well-trained men (21.4 ± 2.9 years; 74.8 ± 6.3 kg; 175.7 ± 5.0 cm) performed two concurrent training sessions with different intra-session exercise sequences: CT1 (aerobic exercise + resistance exercises) and CT2 (resistance exercises + aerobic exercise). The resistance exercises were bench-press, lat-pull down, and shoulder-press (three sets to failure; 2 s cadence for the concentric and eccentric phases; 90 s rest interval between sets and exercises; 75% 1RM), and the aerobic exercise was 4-km running. Each concurrent training session was randomized to placebo, beetroot juice, and control (no substances), totaling six exercise sessions. The rate of perceived exertion (RPE) was reported at the end of each exercise in each session. The beetroot juice significantly increased plasma nitric oxide concentration from 14.5 ± 3.9 mmol/L to 140.2 ± 37.5 mmol/L (P < 0.01) and there was no significant change after placebo intake (13.8 ± 4.2 vs 15.1 ± 5.7 mmol/L). The 4-km running time was significantly less (P < 0.05) after beetroot juice intake in CT1 (17.0 ± 2.1 min) and CT2 (18.5 ± 1.9 min) than placebo (19.1 ± 3.2 and 22.2 ± 2.9 min, respectively) and control (19.4 ± 2.6 and 21.7 ± 3.0 min, respectively). No differences were identified in the total number of repetitions in resistance exercises and RPE. In conclusion, the acute intake of in natura beetroot juice decreased the 4-km running time independently of concurrent training exercise sequences. Our results may assist trainers in order to choose the supplement to increase performance.