title: Profiling Isokinetic Strength by Leg Preference and Position in Rugby Union Athletes.
abstract: BACKGROUND
  Muscle imbalances aid in the identification of athletes at risk for lower-extremity injury. Little is known regarding the influence that leg preference or playing position may have on lower-extremity muscle strength and asymmetry.
  
  
  OBJECTIVE
  To investigate lower-extremity strength profiles in rugby union athletes and compare isokinetic knee- and hip-strength variables between legs and positions.
  
  
  METHODS
  Thirty male academy rugby union athletes, separated into forwards (n = 15) and backs (n = 15), participated in this cross-sectional analysis. Isokinetic dynamometry was used to evaluate peak torque, angle of peak torque, and strength ratios of the preferred and nonpreferred legs during seated knee extension/flexion and supine hip extension/flexion at 60°/s.
  
  
  RESULTS
  Backs were older (ES = 1.6) but smaller in stature (ES = -0.47) and body mass (ES = -1.3) than the forwards. The nonpreferred leg was weaker than the preferred leg for forwards during extension (ES = -0.37) and flexion (ES = -0.21) actions and for backs during extension (ES = -0.28) actions. Backs were weaker at the knee than forwards in the preferred leg during extension (ES = -0.50) and flexion (ES = -0.66) actions. No differences were observed in strength ratios between legs or positions. Backs produced peak torque at longer muscle lengths in both legs at the knee (ES = -0.93 to -0.94) and hip (ES = -0.84 to -1.17) than the forwards.
  
  
  CONCLUSIONS
  In this sample of male academy rugby union athletes, the preferred leg and forwards displayed superior strength compared with the nonpreferred leg and backs. These findings highlight the importance of individualized athletic assessments to detect crucial strength differences in male rugby union athletes.
authors.affiliation: Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Brown
authors.forename: Matt
authors.initials: M
authors.lastname: Brughelli
authors.forename: Lee A
authors.initials: LA
authors.lastname: Bridgeman
mesh_terms: D054874:Athletic Performance / Q000502:physiology*; D003430:Cross-Sectional Studies; D005538:Football / Q000502:physiology*; D006615:Hip / Q000502:physiology*; D006801:Humans; D007717:Knee / Q000502:physiology*; D007866:Leg / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D064797:Physical Conditioning, Human; D019415:Torque; D055815:Young Adult