title: The effects of beetroot juice supplementation on indices of muscle damage following eccentric exercise.
abstract: OBJECTIVE
  Foods rich in antioxidant and anti-inflammatory phytochemicals might attenuate skeletal muscle damage; thus, the present study investigated whether consuming an antioxidant rich beetroot juice would attenuate the muscle-damaging effects of eccentric exercise.
  
  
  METHODS
  Using a double blind, independent groups design, 30 recreationally active males were allocated to consume a high dose of beetroot juice (H-BT; 250 ml), a lower dose of beetroot juice (L-BT; 125 ml), or an isocaloric placebo (PLA; 250 ml) immediately (×3 servings), 24 (×2 servings) and 48 h (×2 servings) following completion of 100-drop jumps. Maximal isometric voluntary contractions (MIVC), countermovement jumps (CMJ), pressure pain threshold (PPT), creatine kinase (CK), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-α (TNF-α) were measured pre, post, 2 (blood indices only), 24, 48 and 72 h following the drop jumps.
  
  
  RESULTS
  CMJ performance recovered quicker (relative to baseline) in H-BT vs. PLA at 48 (91.7 ± 12.2 vs. 74.4 ± 17.3%; P = 0.009, ES = 1.00) and 72 h postexercise (93.4 ± 7.7 vs. 86 ± 5.9%; P = 0.046, ES = 1.25). PPT was greater in both the H-BT and L-BT vs. PLA at 24, 48 and 72 h postexercise (P < 0.001); PPT had returned to baseline in H-BT and L-BT at 72 h postexercise, but was still reduced in PLA (80.1 ± 28.9% of baseline values). MIVC, CK, IL-6, TNF-α and IL-8 were unaffected by beetroot juice (P > 0.05).
  
  
  CONCLUSIONS
  Acute beetroot juice supplementation attenuated muscle soreness and decrements in CMJ performance induced by eccentric exercise; further research on the anti-inflammatory effects of beetroot juice are required to elucidate the precise mechanisms.
authors.affiliation: Faculty of Health and Life Sciences, Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle, UK. tom.clifford@northumbria.ac.uk.
authors.forename: Tom
authors.initials: T
authors.lastname: Clifford
authors.affiliation: Faculty of Health and Life Sciences, Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle, UK.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bell
authors.affiliation: Faculty of Health and Life Sciences, Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle, UK.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: West
authors.affiliation: Faculty of Health and Life Sciences, Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle, UK.|Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, South Africa.
authors.forename: Glyn
authors.initials: G
authors.lastname: Howatson
authors.affiliation: Faculty of Health and Life Sciences, Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle, UK.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Stevenson
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D027461:Beta vulgaris / Q000737:chemistry*; D016207:Cytokines / Q000097:blood; D019587:Dietary Supplements; D015444:Exercise; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology; D063806:Myalgia / Q000188:drug therapy* / Q000517:prevention & control; D017288:Pain Threshold / Q000187:drug effects; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000975:Antioxidants; D016207:Cytokines; D010936:Plant Extracts
keywords: Betalains; Exercise recovery; Inflammation; Muscle damage