title: Effects of Beetroot Juice on Recovery of Muscle Function and Performance between Bouts of Repeated Sprint Exercise.
abstract: This study examined the effects of beetroot juice (BTJ) on recovery between two repeated-sprint tests. In an independent groups design, 20 male, team-sports players were randomized to receive either BTJ or a placebo (PLA) (2 × 250 mL) for 3 days after an initial repeated sprint test (20 × 30 m; RST1) and after a second repeated sprint test (RST2), performed 72 h later. Maximal isometric voluntary contractions (MIVC), countermovement jumps (CMJ), reactive strength index (RI), pressure-pain threshold (PPT), creatine kinase (CK), C-reactive protein (hs-CRP), protein carbonyls (PC), lipid hydroperoxides (LOOH) and the ascorbyl free radical (A(•-)) were measured before, after, and at set times between RST1 and RST2. CMJ and RI recovered quicker in BTJ compared to PLA after RST1: at 72 h post, CMJ and RI were 7.6% and 13.8% higher in BTJ vs. PLA, respectively (p < 0.05). PPT was 10.4% higher in BTJ compared to PLA 24 h post RST2 (p = 0.012) but similar at other time points. No group differences were detected for mean and fastest sprint time or fatigue index. MIVC, or the biochemical markers measured (p > 0.05). BTJ reduced the decrement in CMJ and RI following and RST but had no effect on sprint performance or oxidative stress.
authors.affiliation: Faculty of Health and Life Sciences, Department of Sport, Exercise & Rehabilitation, Northumbria University, Newcastle NE1 8ST, UK. tom.clifford@northumbria.ac.uk.
authors.forename: Tom
authors.initials: T
authors.lastname: Clifford
authors.affiliation: Faculty of Health Medicine and Life Sciences, Maastricht University, Maastricht 6211 LK, The Netherlands. bram.berntzen@student.maastrichtuniversity.nl.
authors.forename: Bram
authors.initials: B
authors.lastname: Berntzen
authors.affiliation: Sport and Exercise Sciences Research Institute, Ulster University, Ulster BT52 1SA, Northern Ireland, UK. gw.davison@ulster.ac.uk.
authors.forename: Gareth W
authors.initials: GW
authors.lastname: Davison
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Newcastle NE2 4HH, UK. daniel.west@newcastle.ac.uk.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: West
authors.affiliation: Faculty of Health and Life Sciences, Department of Sport, Exercise & Rehabilitation, Northumbria University, Newcastle NE1 8ST, UK. glyn.howatson@northumbria.ac.uk.|Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom 2520, South Africa. glyn.howatson@northumbria.ac.uk.
authors.forename: Glyn
authors.initials: G
authors.lastname: Howatson
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Newcastle NE2 4HH, UK. emma.stevenson@newcastle.ac.uk.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Stevenson
mesh_terms: D056352:Athletes; D054874:Athletic Performance; D027461:Beta vulgaris / Q000737:chemistry*; D004311:Double-Blind Method; D004326:Drinking; D000067030:Fruit and Vegetable Juices; D000072696:High-Intensity Interval Training; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000187:drug effects; D053580:Muscle Strength / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects*; D017288:Pain Threshold / Q000187:drug effects; D005082:Physical Exertion / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D020127:Recovery of Function / Q000187:drug effects*; D055815:Young Adult
chemical_list: D010936:Plant Extracts
keywords: beetroot juice; exercise recovery; muscle damage; repeated sprint exercise