title: Effect of Injury Prevention Programs that Include the Nordic Hamstring Exercise on Hamstring Injury Rates in Soccer Players: A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  Hamstring injuries are among the most common non-contact injuries in sports. The Nordic hamstring (NH) exercise has been shown to decrease risk by increasing eccentric hamstring strength.
  
  
  OBJECTIVE
  The purpose of this systematic review and meta-analysis was to investigate the effectiveness of the injury prevention programs that included the NH exercise on reducing hamstring injury rates while factoring in athlete workload.
  
  
  METHODS
  Two researchers independently searched for eligible studies using the following databases: the Cochrane Central Register of Controlled Trials via OvidSP, AMED (Allied and Complementary Medicine) via OvidSP, EMBASE, PubMed, MEDLINE, SPORTDiscus, Web of Science, CINAHL and AusSportMed, from inception to December 2015. The keyword domains used during the search were Nordic, hamstring, injury prevention programs, sports and variations of these keywords. The initial search resulted in 3242 articles which were filtered to five articles that met the inclusion criteria. The main inclusion criteria were randomized controlled trials or interventional studies on use of an injury prevention program that included the NH exercise while the primary outcome was hamstring injury rate. Extracted data were subjected to meta-analysis using a random effects model.
  
  
  RESULTS
  The pooled results based on total injuries per 1000 h of exposure showed that programs that included the NH exercise had a statistically significant reduction in hamstring injury risk ratio [IRR] of 0.490 (95 % confidence interval [CI] 0.291-0.827, p = 0.008). Teams using injury prevention programs that included the NH exercise reduced hamstring injury rates up to 51 % in the long term compared with the teams that did not use any injury prevention measures.
  
  
  CONCLUSIONS
  This systematic review and meta-analysis demonstrates that injury prevention programs that include NH exercises decrease the risk of hamstring injuries among soccer players. A protocol was registered in the International Prospective Register of Systematic Reviews, PROSPERO (CRD42015019912).
authors.affiliation: Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, 75 East Street, Lidcombe, NSW, 2141, Australia. wala3431@uni.sydney.edu.au.|Discipline of Physiotherapy, Faculty of Health Sciences, The University of Sydney, Lidcombe, NSW, 2141, Australia. wala3431@uni.sydney.edu.au.|Department of Physiotherapy and Rehabilitation Sciences, Faculty of Applied Medical Sciences, Umm Al Qura University, Makkah, 24382, Saudi Arabia. wala3431@uni.sydney.edu.au.
authors.forename: Wesam Saleh A
authors.initials: WSA
authors.lastname: Al Attar
authors.affiliation: Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, 75 East Street, Lidcombe, NSW, 2141, Australia.|Rural Health Mildura, Faculty of Medicine, Nursing and Health Sciences, Monash University, Mildura, VIC, 3500, Australia.
authors.forename: Najeebullah
authors.initials: N
authors.lastname: Soomro
authors.affiliation: Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, 75 East Street, Lidcombe, NSW, 2141, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Sinclair
authors.affiliation: Discipline of Physiotherapy, Faculty of Health Sciences, The University of Sydney, Lidcombe, NSW, 2141, Australia.
authors.forename: Evangelos
authors.initials: E
authors.lastname: Pappas
authors.affiliation: Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, 75 East Street, Lidcombe, NSW, 2141, Australia.
authors.forename: Ross H
authors.initials: RH
authors.lastname: Sanders
mesh_terms: D001265:Athletic Injuries / Q000517:prevention & control*; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods; D006801:Humans; D007869:Leg Injuries / Q000517:prevention & control*; D018482:Muscle, Skeletal / Q000293:injuries; D012916:Soccer / Q000293:injuries*; D017695:Soft Tissue Injuries / Q000517:prevention & control