**Background:** Beetroot contains bioactive compounds including betaine and nitrate that may benefit cardiovascular function. While some evidence suggests beetroot juice can improve blood pressure and exercise performance, the effects of beetroot extract (as opposed to juice) on recovery from submaximal aerobic exercise remain unclear. This study investigated whether a 600 mg beetroot extract capsule could accelerate recovery of cardiovascular and autonomic parameters after submaximal aerobic exercise in healthy males.
**Methods:** Sixteen healthy physically active males (age not explicitly reported in the results section; inclusion criteria 18–30 years) completed this crossover, randomized, double-blind, placebo-controlled trial. Participants ingested either 600 mg beetroot extract (standardized to 10% betaine and 2.5% nitrate) or 600 mg starch placebo 120 minutes prior to exercise on two separate days with a minimum 48-hour washout. Exercise consisted of a 5-minute warm-up at 50–55% estimated HRmax followed by 20 minutes at 65–70% estimated HRmax on a treadmill. Outcomes included systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), mean arterial pressure (MAP), heart rate (HR), and heart rate variability (HRV) indices (RMSSD and HF in ms²) measured at rest and at multiple time points during 60 minutes of seated recovery. Two-way repeated measures ANOVA with Greenhouse-Geisser correction was used for analysis, with Ryan-Holm-Bonferroni correction for multiple comparisons. Effect sizes were calculated using Cohen's d.
**Key Results:** For blood pressure, in the placebo protocol SBP remained significantly elevated above rest for 5 minutes post-exercise (Rest: 119±8 mmHg vs. 1st min: 134±8 mmHg, Cohen's d=1.73, p<0.001; Rest vs. 5th min: 124±6 mmHg, Cohen's d=0.99, p<0.001). In the beetroot protocol, SBP was only significantly elevated at 1 minute post-exercise (Rest: 119±10 vs. 1st min: 133±8 mmHg, Cohen's d=1.35, p<0.001), with no significant difference at 5 minutes (123±7 mmHg, p>0.05). DBP was significantly elevated only at 1 minute in the placebo protocol (Rest: 80±3 vs. 84±10 mmHg, Cohen's d=0.56, p<0.001) but not in the beetroot protocol. However, no group effects were found for SBP (p=0.90), DBP (p=0.88), MAP (p=0.73), or PP (p=0.99), and no group×time interactions were significant (SBP p=0.75, DBP p=0.79, MAP p=0.93, PP p=0.63). For HR, the placebo protocol showed elevated HR for 10 minutes post-exercise (Rest: 76±9 bpm vs. 0–5 min: 91±8 bpm, Cohen's d=1.75, p<0.001; Rest vs. 5–10 min: 85±9 bpm, Cohen's d=0.96, p<0.001), while the beetroot protocol showed elevation only during 0–5 minutes (Rest: 78±12 vs. 92±9 bpm, Cohen's d=1.26, p<0.001). For HF index, the placebo protocol showed reduction for 10 minutes (Rest: 313.25±246.39 ms² vs. 0–5 min: 119.06±96.99 ms², Cohen's d=−1.00, p<0.001; Rest vs. 5–10 min: 120.50±83.53 ms², Cohen's d=−1.01, p<0.001), while beetroot showed reduction only for 5 minutes (Rest: 331.87±234.82 vs. 0–5 min: 148.50±131.80 ms², Cohen's d=−0.93, p<0.0001). RMSSD remained reduced for 10 minutes in both protocols. No group effects were found for HR mean (p=0.99), HF (p=0.90), or RMSSD (p=0.67), and no group×time interactions were significant (HR p=0.60, HF p=0.69, RMSSD p=0.95).
**Clinical Implications:** This study demonstrates that 600 mg of beetroot extract produces only negligible, statistically non-significant improvements in cardiovascular and autonomic recovery after submaximal aerobic exercise in healthy young males. While the beetroot extract slightly accelerated the return of SBP, HR, and HF index toward resting values (by approximately 5 minutes), the lack of significant group or interaction effects indicates these differences are clinically weak. The findings contrast with more pronounced benefits observed in prior studies using high-intensity exercise, suggesting that exercise intensity may be a key moderator of beetroot extract's effects. The low nitrate content (approximately 15 mg per 600 mg capsule based on 2.5% standardization) may also explain the minimal effects. Clinicians and sports nutritionists should not expect meaningful recovery benefits from beetroot extract at this dose for submaximal aerobic exercise in healthy populations. Limitations include the small sample (though exceeding the calculated minimum of 11), lack of plasma nitrate/nitrite measurements, exercise prescription based on estimated HR rather than direct VO₂ measurement, and exclusion of females. Further research with higher doses, different exercise intensities, and clinical populations is warranted.