Impact of beetroot juice ingestion on upper- and lower-body muscular endurance in resistance-trained females: A randomized, double-blind, crossover study

Background: Nitrate-rich beetroot juice offers potential ergogenic effects in resistance training. However, existing literature overwhelmingly focuses on males, leaving a significant gap regarding female responses. Aim: This study evaluated acute effects of inorganic nitrate (NO3−) supplementation on resistance exercise performance to failure in recreationally trained females. Methods: In a randomized, double-blind, placebo-controlled, crossover trial, sixteen females (27 ± 4.7 years; one repetition maximum [1RM] bench press: 31.4 ± 6.5 kg; 1RM leg press: 198.6 ± 44.0 kg) performed four sets of bench press and 45° leg press to concentric failure at 60% of 1RM (2-min rest intervals) following the ingestion of nitrate-rich beetroot juice (BEET It Sport®: 12.8 mmol NO3−), a placebo drink (0.92 mmol NO3−), or nothing (control) 2.5 h before exercise. Results: Nitrate-rich beetroot juice ingestion had no effect on performance in either the upper-body (bench press total repetitions: Control: 55.6 ± 9.7 reps; Placebo: 58.9 ± 13.0 reps; Nitrate: 56.0 ± 14.0 reps, p = 0.785, ηp2 = 0.003) or lower-body (leg press total repetitions: Control: 82.6 ± 36.0 reps; Placebo: 80.4 ± 37.0 reps; Nitrate: 79.3 ± 30.0 reps, p = 0.945, ηp2 = 0.001) exercises in resistance-trained females. There were also no effects of nitrate on rating of perceived exertion, heart rate, blood pressure, or lactate compared to placebo (p > 0.05). Summary: Acute NO3− supplementation did not alter performance or modulate the physiological response to resistance exercise in recreationally trained females. These results suggest that the ergogenic potential of NO3− may be limited in this population.