title: A comparison of hamstring muscle activity during different screening tests for non-contact ACL injury.
abstract: BACKGROUND
  Reduced ability to activate the medial hamstring muscles during a sports-specific sidecutting movement has been found to be a potential risk factor for non-contact ACL injury. However, whether a reduced ability to activate the medial hamstring muscle is a general neuromuscular phenomenon and thereby observable independently of the type of clinical screening tests used is not known. This cross sectional study investigated the rank correlation of knee joint neuromuscular activity between three different ACL injury risk screening tests.
  
  
  METHODS
  Sixty-two adolescent female elite football and handball players (16.7±1.3years) participated in the study. Using surface electromyography (EMG) assessment, the neuromuscular activity of medial hamstring muscle (semitendinosus, ST), lateral hamstring muscle (biceps femoris, BF) and quadriceps muscle (vastus lateralis, VL) were monitored during three standardized screening tests - i.e. one-legged horizontal hop (OLH), drop vertical jump (DJ) and sidecutting (SC). Neuromuscular pre-activity was measured in the time interval 10ms prior to initial contact on a force plate.
  
  
  RESULTS
  For neuromuscular hamstring muscle pre-activity, correlation analysis (Spearman correlation coefficient) showed low-to-moderate correlations between SC and 1) DJ (rs=0.34-0.36, P<0.05) and 2) OLH (rs=0.40-0.41, P<0.05), respectively.
  
  
  CONCLUSIONS
  In conclusion, the present data suggest that hamstring pre-activity share some common variance during the examined tests. However, a lack of strong correlation suggests that we cannot generalize one risk factor during one test to another test.
  
  
  CONCLUSIONS
  The present data demonstrate that one-legged horizontal hop and drop vertical jump testing that are commonly used in the clinical setting does not resemble the specific neuromuscular activity patterns known to exist during sidecutting, a well known high risk movement for non-contact ACL injury.
authors.affiliation: Laboratory of Human Movement Analysis, Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Denmark; Clinical Research Centre, Copenhagen University Hospital, Amager-Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Denmark.
authors.forename: Rasmus S
authors.initials: RS
authors.lastname: Husted
authors.affiliation: Laboratory of Human Movement Analysis, Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Bencke
authors.affiliation: National Research Centre for the Working Environment, Lersø Parkallé 105, 2100 Copenhagen, Denmark; Physical Activity and Human Performance Group, SMI, Department of Health Science and Technology, Aalborg University, Denmark.
authors.forename: Lars L
authors.initials: LL
authors.lastname: Andersen
authors.affiliation: Oslo Sport Trauma Research Center, Norwegian School of Sport Sciences, PB 4014 Ullevål Stadion, 0806 Oslo, Norway.
authors.forename: Grethe
authors.initials: G
authors.lastname: Myklebust
authors.affiliation: Clinical Research Centre, Copenhagen University Hospital, Amager-Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Denmark; Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kallemose
authors.affiliation: Laboratory of Human Movement Analysis, Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Denmark.
authors.forename: Hanne B
authors.initials: HB
authors.lastname: Lauridsen
authors.affiliation: Sports Orthopedic Research Center - Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Hölmich
authors.affiliation: Institute of Sports Sciences and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Aagaard
authors.affiliation: Laboratory of Human Movement Analysis, Department of Orthopaedic Surgery, Copenhagen University Hospital, Amager-Hvidovre, Kettegård Alle 30, 2650 Hvidovre, Denmark. Electronic address: mettezebis@hotmail.com.
authors.forename: Mette K
authors.initials: MK
authors.lastname: Zebis
mesh_terms: D000293:Adolescent; D000070598:Anterior Cruciate Ligament Injuries / Q000175:diagnosis* / Q000503:physiopathology; D001265:Athletic Injuries / Q000175:diagnosis* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D000070633:Hamstring Muscles / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008403:Mass Screening; D009119:Muscle Contraction / Q000502:physiology*; D018570:Risk Assessment
keywords: Anterior cruciate ligament; Electromyography; Hamstrings; Neuromuscular activity