Table 2.
Variables measured and summary of findings of the included studies
| Study | Functional Measures and Muscle Soreness | Biochemical Markers of Muscle Damage, Inflammation, and Oxidative Stress | Significant Differences in BR Group (vs PLA/SN Group) |
|---|---|---|---|
| Clifford et al 12 | Muscle soreness of lower limb, MIVC of knee extensors, CMJ. Measurements: baseline, post and 24 h, 48 h, and 72 h post | CK; TNF-α, IL-1β, IL-6, IL-8. Measurements: baseline, post and 2 h, 24 h, 48 h, 72 h post |
>CMJ 48 h and 72 h post in HD <Muscle soreness 24 h, 48 h, and 72 h post in HD and LD |
| Clifford et al 13 | Muscle soreness of the lower limb, MIVC of knee extensors, CMJ, RSI. Measurements: baseline, post and 24 h, 48 h, 72 h post RST1; post and 24 post RST2 (96 h post RST1) | CK; CRP; PC, LOOH, AFR Measurements: baseline, post and 2.5 h, 24 h, 48 h, 72 h post RST1, post and 2.5 h, 24 h post RST2 (96 h post RST1) |
>recovery of CMJ from 24 h post RST1 >RSI throughout the trial <Muscle soreness 96 h post RST1 |
| Montenegro et al 37 | Whole body muscle soreness. Measurements: baseline, post, and 24 h post. 5 km TT. Measurements: 24 h post |
CK, LDH Measurements made baseline, post and 24 h post |
<5 km TT 24 h post <CK post |
| Clifford et al 11 | Muscle soreness of lower limb, MIVC of knee extensors, CMJ. Measurements: baseline, post and 24 h, 48 h post | CK, AST; TNF-α, IL-1ra, -2, -4, -6, -8, -10, IFN-γ, CRP Measurements: baseline, post and 48 h post |
No significant differences between groups |
| Clifford et al 15 | Muscle soreness of lower limb, MIVC of knee extensors, CMJ. Measurements: baseline, post and 24 h, 48 h, 72 h post | CK; CRP Measurements: baseline, post and 2,5 h, 24 h, 48 h, 72 h post |
<Muscle soreness in BR group vs SN and PLA in the 72-h postexercise period |
| Carriker et al 8 | — | Cat (baseline and post) 8-IsoP (baseline and 1 h post) |
No significant differences between groups |
| Clifford et al 14 | — | mtDNA damage; ROS production Measurements: baseline, pre, post, and 24 h post |
No significant differences between groups |
| Daab et al 16 | Muscle soreness of quadriceps and hamstrings, MIVC of knee extensors, SJ, CMJ, 20-m SP. Measurements: baseline, post and 24 h, 48 h, 72 h post | CK, LDH; CRP Measurements: baseline, post and 24 h, 48 h, and 72 h post |
>CMJ 24 h, 48 h, and 72 h post. >MIVC post, 24 h and 48 h. <SP 48 h post <Muscle soreness post and 24 h post |
| Kozłowska et al 30 | — | CK, LDH; IL-6, CP; AOPP, MDA, GPx-1, GPx-3, 8-oxodG Measurements: pre and post (4 weeks after) |
>Gpx-1 post >MDA post |
8-IsoP, 8-isoprostane; 8-oxodG, 8-oxo-deoxyguanosine; AFR, ascorbyl free radical; AOPP, advanced oxidation protein products; AST, aspartate transaminase; BR, beetroot; Cat, catalase; CK, creatine kinase; CMJ, countermovement jump; CP, ceruloplasmin; CRP, C-reactive protein; GPx, glutathione peroxidase; HD, high dose; IFN-γ, interferon-γ; IL, interleukin; LD, low dose; LDH, lactate dehydrogenase; LOOH, lipid hydroperoxides; MDA, malondialdehyde; MIVC, maximal isometric voluntary contraction; mtDNA, mitochondrial DNA; PC, protein carbonyls; PLA, placebo; post, postexercise; pre, pre-exercise; ROS, reactive oxygen species; RSI, reactive strength index; RST, repeated sprint test; SJ, squat jump; SN, sodium nitrate; SP, sprint performance; TNF-α, tumor necrosis factor alpha.