title: The efficacy of acute nutritional interventions on soccer skill performance.
abstract: BACKGROUND
  The use of nutritional ergogenic aids in team sports such as soccer is now commonplace. Aligned with the primary aim of soccer, which is to score more goals than the opposition within the allotted time, the quality of performance of technical actions (i.e., skills) executed during soccer-specific exercise is likely to determine success. However, when seeking to maintain soccer skill performance, information about the efficacy of nutritional interventions is lacking and factors which might modulate the efficacy of such strategies are unclear.
  
  
  OBJECTIVE
  This review aimed (i) to systematically evaluate the current research that examines the efficacy of nutritional interventions on soccer skills, and (ii) to provide a qualitative commentary on factors that have the potential to modulate the efficacy of such strategies.
  
  
  METHODS
  Relevant databases (PubMed and SPORTDiscus) were searched up to and including 1 July, 2013 for studies that investigated the efficacy of acute nutritional interventions on soccer skill performances.
  
  
  METHODS
  Overall, 279 records were retrieved. Articles were sequentially excluded from the review based on specific criteria, being: (A) articles that did not report outcomes directly relating to skilled performances in soccer, (B) articles that examined the influence of interventions that were not nutritional in origin and/or were nutritional in origin but provided >3 hours before skill testing commenced, (C) articles that were review papers, and (D) post-acceptance withdrawal of articles methods from database.
  
  
  METHODS
  Articles were independently assessed for the quality of the methods employed based upon the Physiotherapy Evidence Database (PEDro) scale. Records achieving a minimum PEDro score of 5 out of 10 were included in this review. Qualitative appraisal of 13 articles was performed after the application of exclusion criteria and quality assurance processes. The majority (n = 8) of articles examined the influence of carbohydrates on technical performance whereas fewer studies investigated the influence of caffeine ingestion (n = 2) and fluid provision (n = 3).
  
  
  RESULTS
  Findings were reported for a total of 171 participants and all but one of the included articles used cross-over study designs. Most participants (94 %) were male, highly trained (reported maximal aerobic capacity range 50-59 ml·kg(-1)·min(-1)) and exercised in temperate environments (reported temperature range 13-25 °C). Six of the eight studies reported that carbohydrates, consumed in the form of a 6-8 % solution of glucose, sucrose or maltodextrin at rates of 30-60 g·h(-1), enhanced at least one aspect of skilled performance over the duration of exercise (75-90 min). Although some evidence exists to support the consumption of caffeine (6 mg·kg(-1) body mass [BM]) and prescribed fluid to preserve skills performed during soccer-specific exercise, findings from the small number of included studies were inconsistent.
  
  
  CONCLUSIONS
  The outcome measures and methods used to quantify skilled performance were not consistent across studies; consequently, it was not possible to perform meta-analyses to produce pooled effect sizes in this review.
  
  
  CONCLUSIONS
  The findings from this systematic review suggest that nutritional interventions, which provide carbohydrate, caffeine and fluid, have potential to preserve skills performed under conditions that induce soccer-specific fatigue. The weight of current evidence supports the consumption of carbohydrate, but is less conclusive with respect to caffeine and fluid provision. It is likely that the efficacy of a nutritional intervention will be modulated by factors including the dose consumed, the mode of administration, individual responsiveness to the intervention and interactions with other physiological changes occurring during soccer-specific exercise. Consequently, these factors should be considered when using carbohydrates, caffeine and fluid provision to maintain skilled performances in soccer. Future research should seek to optimise the nutritional strategies employed to maintain technical performance throughout match-play.
authors.affiliation: Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, UK, mark.russell@northumbria.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Russell
authors.forename: Michael
authors.initials: M
authors.lastname: Kingsley
mesh_terms: D054874:Athletic Performance / Q000502:physiology*; D001628:Beverages; D001786:Blood Glucose / Q000378:metabolism; D002110:Caffeine / Q000008:administration & dosage*; D002214:Capsules; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D019587:Dietary Supplements; D005221:Fatigue / Q000517:prevention & control; D005440:Fluid Therapy; D006801:Humans; D012916:Soccer / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D002214:Capsules; D004040:Dietary Carbohydrates; D002110:Caffeine
references.citation: Sports Med. 2009;39(10):813-32
references.pmid: 19757860
references.citation: Scand J Med Sci Sports. 2011 Jun;21(3):437-45
references.pmid: 20136761
references.citation: Eur J Appl Physiol. 2010 Jul;109(5):811-21
references.pmid: 20229023
references.citation: Sports Med. 2007;37(10):907-21
references.pmid: 17887814
references.citation: Psychopharmacology (Berl). 2005 Jun;179(4):813-25
references.pmid: 15678363
references.citation: J Rehabil Med. 2009 Nov;41(11):870-80
references.pmid: 19841837
references.citation: J Athl Train. 2014 Jul-Aug;49(4):447-53
references.pmid: 24933430
references.citation: Med Sci Sports Exerc. 1992 Jun;24(6):671-8
references.pmid: 1602939
references.citation: J Physiol. 2009 Apr 15;587(Pt 8):1779-94
references.pmid: 19237430
references.citation: Eur J Appl Physiol Occup Physiol. 1982;48(3):297-302
references.pmid: 7200872
references.citation: J Sports Sci. 2011 Jan;29(1):63-71
references.pmid: 21077004
references.citation: J Appl Physiol (1985). 2001 Oct;91(4):1535-44
references.pmid: 11568134
references.citation: Aviat Space Environ Med. 2005 Jul;76(7):647-54
references.pmid: 16018347
references.citation: J Appl Physiol (1985). 1986 Jul;61(1):165-72
references.pmid: 3525502
references.citation: Eur J Appl Physiol. 2003 Jan;88(4-5):444-52
references.pmid: 12527976
references.citation: Int J Sport Nutr Exerc Metab. 2009 Feb;19(1):34-46
references.pmid: 19403952
references.citation: Eur J Appl Physiol. 2003 Jan;88(4-5):453-8
references.pmid: 12527977
references.citation: Cell Mol Neurobiol. 1983 Mar;3(1):69-80
references.pmid: 6309393
references.citation: J Strength Cond Res. 2011 Jul;25(7):1816-23
references.pmid: 21478767
references.citation: J Sports Sci. 1999 Nov;17(11):895-903
references.pmid: 10585169
references.citation: Nutrition. 2010 Oct;26(10):932-8
references.pmid: 20888549
references.citation: PLoS Med. 2009 Jul 21;6(7):e1000100
references.pmid: 19621070
references.citation: Med Sci Sports Exerc. 2005 Nov;37(11):1998-2005
references.pmid: 16286872
references.citation: Med Sci Sports Exerc. 2005 Dec;37(12):2113-9
references.pmid: 16331138
references.citation: Int J Sports Physiol Perform. 2007 Sep;2(3):250-9
references.pmid: 19168925
references.citation: Med Sci Sports Exerc. 1989 Feb;21(1):59-65
references.pmid: 2927302
references.citation: Sports Med. 2011 Jul 1;41(7):559-85
references.pmid: 21688869
references.citation: News Physiol Sci. 2001 Apr;16:71-6
references.pmid: 11390952
references.citation: Med Sci Sports Exerc. 1998 Nov;30(11):1624-30
references.pmid: 9813876
references.citation: Med Sci Sports Exerc. 2005 Feb;37(2):306-15
references.pmid: 15692328
references.citation: Sports Med. 2000 Mar;29(3):181-209
references.pmid: 10739268
references.citation: J Strength Cond Res. 2013 Aug;27(8):2235-47
references.pmid: 23168373
references.citation: Eur J Appl Physiol. 2003 Jan;88(4-5):466-71
references.pmid: 12527979
references.citation: Br J Pharmacol. 2012 Mar;165(6):1904-1913
references.pmid: 21950736
references.citation: Int J Sport Nutr. 1997 Jun;7(2):128-37
references.pmid: 9189783
references.citation: Nutrients. 2013 Dec 19;6(1):1-10
references.pmid: 24451304
references.citation: Int J Pharm. 2002 Mar 2;234(1-2):159-67
references.pmid: 11839447
references.citation: Med Sci Sports Exerc. 2002 Apr;34(4):723-31
references.pmid: 11932585
references.citation: Int J Sports Physiol Perform. 2011 Jun;6(2):174-82
references.pmid: 21725103
references.citation: Med Sci Sports Exerc. 1994 Mar;26(3):267-80
references.pmid: 8183089
references.citation: Int J Sports Med. 1992 Feb;13(2):152-7
references.pmid: 1555905
references.citation: J Sci Med Sport. 2014 Mar;17(2):239-43
references.pmid: 23702257
references.citation: Nutrition. 2004 Jul-Aug;20(7-8):669-77
references.pmid: 15212750
references.citation: J Sports Sci. 2005 Jun;23(6):593-9
references.pmid: 16195008
references.citation: Diabetes Obes Metab. 2005 Sep;7(5):493-503
references.pmid: 16050942
references.citation: Med Sci Sports Exerc. 2008 May;40(5):934-42
references.pmid: 18408603
references.citation: Appl Physiol Nutr Metab. 2013 Jun;38(6):633-7
references.pmid: 23724880
references.citation: Sports Med. 2009;39(1):1-13
references.pmid: 19093692
references.citation: Med Sci Sports. 1973 Fall;5(3):137-46
references.pmid: 4270581
references.citation: Int J Sports Med. 2007 Mar;28(3):222-7
references.pmid: 17024626
references.citation: J Appl Physiol (1985). 2001 Sep;91(3):1055-60
references.pmid: 11509498
references.citation: J Sports Sci. 2005 May;23(5):509-14
references.pmid: 16194998
references.citation: Brain Res Cogn Brain Res. 1998 Oct;7(2):221-33
references.pmid: 9774737
references.citation: Appl Physiol Nutr Metab. 2008 Dec;33(6):1192-8
references.pmid: 19088777
references.citation: J Sports Sci. 2007 May;25(7):781-96
references.pmid: 17454546
references.citation: J Sports Sci Med. 2002 Jun 20;1(2):47-53
references.pmid: 24688270
references.citation: Sports Med. 2011 Jul 1;41(7):523-39
references.pmid: 21688867
references.citation: Int J Sport Nutr Exerc Metab. 2009 Aug;19(4):410-23
references.pmid: 19827465
references.citation: Med Sci Sports Exerc. 2001 Nov;33(11):1925-31
references.pmid: 11689745
references.citation: Brain Res. 2010 Sep 2;1350:151-8
references.pmid: 20388497
references.citation: Int J Sports Physiol Perform. 2007 Jun;2(2):111-27
references.pmid: 19124899
references.citation: J Sports Sci. 2004 Jan;22(1):39-55
references.pmid: 14971432
references.citation: J Sci Med Sport. 1998 Dec;1(4):203-12
references.pmid: 9923728
references.citation: Int J Sport Nutr. 1996 Dec;6(4):348-55
references.pmid: 8953337
references.citation: Scand J Med Sci Sports. 2004 Jun;14(3):156-62
references.pmid: 15144355
references.citation: J Sci Med Sport. 2013 Jul;16(4):343-7
references.pmid: 22964452
references.citation: Exerc Sport Sci Rev. 1999;27:167-218
references.pmid: 10791017
references.citation: Br J Sports Med. 2008 Sep;42(9):725-30
references.pmid: 18308873
references.citation: Phys Ther. 2003 Aug;83(8):713-21
references.pmid: 12882612
references.citation: Aviat Space Environ Med. 2005 Jan;76(1):39-45
references.pmid: 15672985
references.citation: Int J Sports Physiol Perform. 2009 Jun;4(2):163-75
references.pmid: 19567920
references.citation: Int J Sports Med. 2013 Sep;34(9):800-5
references.pmid: 23444096
references.citation: J Sci Med Sport. 2009 Jan;12(1):227-33
references.pmid: 18083631
references.citation: Hum Psychopharmacol. 2001 Oct;16(7):523-531
references.pmid: 12404548
references.citation: J Sci Med Sport. 2012 Jul;15(4):348-54
references.pmid: 22230353
references.citation: J Strength Cond Res. 2013 Jan;27(1):259-64
references.pmid: 22476164
references.citation: J Sports Sci. 2013;31(1):1-10
references.pmid: 22950541
references.citation: Med Sci Sports Exerc. 2004 Dec;36(12):2107-11
references.pmid: 15570147
references.citation: Int J Sports Med. 2009 Mar;30(3):205-12
references.pmid: 19214939
references.citation: Psychopharmacology (Berl). 2005 Jul;180(3):539-47
references.pmid: 15723227
references.citation: Med Sci Sports Exerc. 2007 Feb;39(2):377-90
references.pmid: 17277604
references.citation: Int J Sports Med. 2011 Jul;32(7):511-8
references.pmid: 21472627
references.citation: Int J Sport Nutr Exerc Metab. 2010 Jun;20(3):191-7
references.pmid: 20601736
references.citation: J Sports Sci. 2009 Dec;27(14):1499-508
references.pmid: 19967596
references.citation: Scand J Med Sci Sports. 2013 Feb;23(1):105-13
references.pmid: 21812822
references.citation: Med Sci Sports Exerc. 2006 Jun;38(6):1165-74
references.pmid: 16775559
references.citation: J Strength Cond Res. 2013 Oct;27(10):2869-73
references.pmid: 23287830
references.citation: Sports Med. 2011 Jun 1;41(6):449-61
references.pmid: 21615187
references.citation: Int J Sport Nutr Exerc Metab. 2009 Dec;19(6):659-72
references.pmid: 20175433
references.citation: Med Sci Sports Exerc. 2007 Nov;39(11):1969-76
references.pmid: 17986904
references.citation: Int J Sports Physiol Perform. 2011 Jun;6(2):221-33
references.pmid: 21725107
references.citation: Sports Med. 2012 Dec 1;42(12):997-1015
references.pmid: 23046224
references.citation: Med Sci Sports Exerc. 1996 Jan;28(1):i-vii
references.pmid: 9303999
references.citation: J Sports Sci. 1995 Aug;13(4):283-90
references.pmid: 7474041
references.citation: J Sports Sci. 2006 Nov;24(11):1165-71
references.pmid: 17035165
references.citation: Med Sci Sports Exerc. 1999 Jan;31(1):164-70
references.pmid: 9927025
references.citation: Psychopharmacology (Berl). 2010 Aug;211(3):245-57
references.pmid: 20532872