The Relationship between Resistance Exercise Performance and Ventilatory Efficiency after Beetroot Juice Intake in Well-Trained Athletes

The assessment of ventilatory efficiency is critical to understanding the matching of ventilation (VE) and perfusion in the lungs during exercise. This study aimed to establish a causal physiological relationship between ventilatory efficiency and resistance exercise performance after beetroot juice (BJ) intake. Eleven well-trained males performed a resistance exercise test after drinking 140 mL of BJ (~12.8 mmol NO₃⁻) or a placebo (PL). Ventilatory efficiency was assessed by the VE•VCO₂⁻¹ slope, the oxygen uptake efficiency slope and the partial pressure of end-tidal carbon dioxide (PetCO₂). The two experimental conditions were controlled using a randomized, double-blind crossover design. The resistance exercise test involved repeating the same routine twice, which consisted of wall ball shots plus a full squat (FS) with a 3 min rest or without a rest between the two exercises. A higher weight lifted was detected in the FS exercise after BJ intake compared with the PL during the first routine (p = 0.004). BJ improved the VE•VCO₂⁻¹ slope and the PetCO₂ during the FS exercise in the first routine and at rest (p < 0.05). BJ intake improved the VE•VCO₂⁻¹ slope and the PetCO₂ coinciding with the resistance exercise performance. The ergogenic effect of BJ could be induced under aerobic conditions at rest.