title: Which Extrinsic and Intrinsic Factors are Associated with Non-Contact Injuries in Adult Cricket Fast Bowlers?
abstract: BACKGROUND
  The high prevalence of injury amongst cricket fast bowlers exposes a great need for research into the risk factors associated with injury. Both extrinsic (environment-related) and intrinsic (person-related) risk factors are likely to be implicated within the high prevalence of non-contact injury amongst fast bowlers in cricket. Identifying and defining the relative importance of these risk factors is necessary in order to optimize injury prevention efforts.
  
  
  OBJECTIVE
  The objective of this review was to assess and summarize the scientific literature related to the extrinsic and intrinsic factors associated with non-contact injury inherent to adult cricket fast bowlers.
  
  
  METHODS
  A systematic review was performed in compliance with the PRISMA guidelines. This review considered both experimental and epidemiological study designs. Studies that included male cricket fast bowlers aged 18 years or above, from all levels of play, evaluating the association between extrinsic/intrinsic factors and injury in fast bowlers were considered for inclusion. The three-step search strategy aimed at finding both published and unpublished studies from all languages. The searched databases included MEDLINE via PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Cochrane Controlled Trials Register in the Cochrane Library, Physiotherapy Evidence Database (PEDro), ProQuest 5000 International, ProQuest Health and Medical Complete, EBSCO MegaFile Premier, Science Direct, SPORTDiscus with Full Text and SCOPUS (prior to 28 April 2015). Initial keywords used were 'cricket', 'pace', 'fast', 'bowler', and 'injury'. Papers which fitted the inclusion criteria were assessed by two independent reviewers for methodological validity prior to inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI).
  
  
  RESULTS
  A total of 16 studies were determined to be suitable for inclusion in this systematic review. The mean critical appraisal score of the papers included in this study was 6.88 (SD 1.15) out of a maximum of 9. The following factors were found to be associated with injury: bowling shoulder internal rotation strength deficit, compromised dynamic balance and lumbar proprioception (joint position sense), the appearance of lumbar posterior element bone stress, degeneration of the lumbar disc on magnetic resonance imaging (MRI), and previous injury. Conflicting results were found for the association of quadratus lumborum (QL) muscle asymmetry with injury. Technique-related factors associated with injury included shoulder-pelvis flexion-extension angle, shoulder counter-rotation, knee angle, and the proportion of side-flexion during bowling. Bowling workload was the only extrinsic factor associated with injury in adult cricket fast bowlers. A high bowling workload (particularly if it represented a sudden upgrade from a lower workload) increased the subsequent risk to sustaining an injury 1, 3 or 4 weeks later.
  
  
  CONCLUSIONS
  Identifying the factors associated with injury is a crucial step which should precede the development of, and research into, the effectiveness of injury prevention programs. Once identified, risk factors may be included in pre-participation screening tools and injury prevention programs, and may also be incorporated in future research projects. Overall, the current review highlights the clear lack of research on factors associated with non-contact injury, specifically in adult cricket fast bowlers.
  Johanna Briggs Institute Database of Systematic Reviews and Implementation Reports 1387 (Olivier et al., JBI Database Syst Rev Implement Rep 13(1):3-13. doi: 10.11124/jbisrir-2015-1387 , 2015).
authors.affiliation: Department of Physiotherapy, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, Gauteng, South Africa. benita.olivier@wits.ac.za.
authors.forename: Benita
authors.identifier: http://orcid.org/0000-0001-9287-8301
authors.initials: B
authors.lastname: Olivier
authors.affiliation: Department of Physiotherapy, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, Gauteng, South Africa.
authors.forename: Tracy
authors.initials: T
authors.lastname: Taljaard
authors.affiliation: Department of Physiotherapy, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, Gauteng, South Africa.
authors.forename: Elaine
authors.initials: E
authors.lastname: Burger
authors.affiliation: Sports Medicine, La Trobe University, Melbourne, VIC, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Brukner
authors.affiliation: School of Public Health, University of Sydney, Sydney, NSW, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Orchard
authors.affiliation: University of Cape Town, Cape Town, South Africa.|Cricket South Africa, Cape Town, South Africa.
authors.forename: Janine
authors.initials: J
authors.lastname: Gray
authors.affiliation: Faculty of Health Sciences, University of Southampton, Southampton, UK.|Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Nottingham, UK.
authors.forename: Nadine
authors.initials: N
authors.lastname: Botha
authors.affiliation: Department of Physiotherapy, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, Gauteng, South Africa.
authors.forename: Aimee
authors.initials: A
authors.lastname: Stewart
authors.affiliation: School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Gauteng, South Africa.
authors.forename: Warrick
authors.initials: W
authors.lastname: Mckinon
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control; D004777:Environment; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology; D008159:Lumbar Vertebrae / Q000473:pathology; D008161:Lumbosacral Region / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D009048:Motor Skills / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D010806:Physical Education and Training; D004856:Postural Balance / Q000502:physiology; D015995:Prevalence; D011434:Proprioception; D012307:Risk Factors; D012399:Rotation; D000070599:Shoulder Injuries