Short-Term Beetroot Juice Supplementation Enhances Strength, Reduces Fatigue, and Promotes Recovery in Physically...

Background/Objectives: Beetroot juice (BJ), a natural source of dietary nitrate, has gained increasing attention for its potential to improve exercise performance and cardiovascular function. While its benefits are well documented in endurance contexts, less is known about its short-term effects on resistance training performance and recovery. Thus, this study investigated the effects of short-term BJ supplementation on strength performance, cardiovascular responses, muscle oxygenation, and post-exercise recovery in resistance-trained males. Methods: Twelve healthy men (age: 21.3 ± 1.9 years; body mass index: 21.42 ± 2.36 kg/m²) completed two supplementation protocols involving BJ, providing 450 mg of nitrate per day, and a nitrate-free placebo (PLA). Each protocol consisted of two laboratory visits, one to assess the acute ergogenic effects and another to evaluate recovery after 72 h, resulting in a total of four sessions over a two-week period. During the three consecutive days of supplementation, participants ingested a single 900 mL dose (15 g BJ powder/PLA) 2 h before the first session, followed by three daily 300 mL doses (5 g BJ each/PLA) over the next two days, and a final dose (15 g BJ powder/PLA) taken 2 h before the second session (72 h post-first session). Each testing session involved incremental back squat (BS) and bench press (BP) exercises at 60%, 70%, and 80% of the one-repetition maximum (1RM) performed to failure, with three-minute rest intervals between sets. Repetition to failure, movement velocity, peak power, peak heart rate (HR), and muscle oxygenation (SmO₂) were recorded during BP and BS exercises. Heart rate variability (HRV) and blood lactate were assessed before and after each training session. Lower-limb strength (CMJ and SJ) and delayed-onset muscle soreness (DOMS) were assessed daily during the 3-day supplementation period. Results: BJ significantly increased repetitions completed at 80% 1RM during BP and BS (p < 0.05) compared to the PLA. Peak movement velocity improved across all intensities using BJ with higher values compared to the PLA at 60-80% 1RM (p < 0.05). SmO₂ was higher in BJ at 70-80% 1RM) and further improved after 72 h of BJ supplementation (p < 0.05). Cardiovascular strain was reduced in BJ, evidenced by lower peak HRs and smaller post-exercise declines in HRV indices (p < 0.05). Post-exercise recovery favored BJ, with faster recovery in jump performance at 24 h and reduced upper-limb DOMS at 24-48 h (p < 0.05). Conclusions: Short-term BJ supplementation enhances high-intensity resistance performance, improves muscle oxygenation, attenuates cardiovascular strain, and accelerates neuromuscular recovery. These benefits highlight its potential as a practical strategy for athletes seeking to optimize training performance and recovery during periods of intense resistance training.