The effect of beetroot juice (BRJ) supplementation on exercise-induced muscle damage (EIMD): a systematic review and...

This systematic review and meta-analysis was conducted to quantify the effect of beetroot juice (BRJ) supplementation on exercise-induced muscle damage (EIMD), inflammatory biomarkers, muscle function, and muscle soreness.

The Robvis tool was used for assessing the risk of bias. The mean differences (MD) and 95% confidence intervals (CI) of creatine kinase (CK) levels (IU/L), C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor-alpha (TNF-α) (pg/ml), maximal voluntary isometric contraction (MVIC), counter movement jump (CMJ), and pressure pain threshold (PPT) (% change from baseline) were pooled using either a fixed- or random-effects model. Between-study heterogeneity was assessed using the χ² or I ² statistic.

Seven trials met the eligibility criteria and were included in the pooled analysis. Meta-analysis indicated that BRJ supplementation significantly reduced serum CK levels [weighted mean difference (WMD) = -98.67 IU/L, 95% CI (-122.14 to -75.21), I ² = 74.2%]. Significant improvement was also observed in MVIC [WMD = 8.93%, 95% CI (7.59-10.28), I ² = 81.2%], CMJ [WMD = 4.72%, 95% CI (4.14-5.30), I ² = 46.3%], and PPT [WMD = 7.22%, 95% CI (5.30-10.93), I ² = 49.4%] from baseline in the intervention group compared to the placebo group. However, no significant change in CRP, IL-6, and TNF-α levels was found. Dose-response analysis revealed that there is a significant non-linear association between the daily dose and antioxidant content (Trolox) of BRJ and the final effect size regarding CK.

BRJ supplementation may improve some aspects of EIMD, including muscle damage, muscle function, and recovery.