title: Quadriceps and hamstrings peak torque ratio changes in persons with chronic anterior cruciate ligament deficiency.
abstract: METHODS
  Cross-sectional analytical study in which subjects served as their own controls.
  
  
  OBJECTIVE
  To assess the concentric and eccentric peak torque in the hamstrings and quadriceps muscles, hamstrings/quadriceps amplitude ratios, and lean thigh volume differences in the involved and uninvolved limb of subjects with anterior cruciate ligament (ACL) deficiency.
  
  
  BACKGROUND
  [corrected] Although the hamstrings/quadriceps ratios for concentric and eccentric activity have been studied, the more functional eccentric hamstings/concentric quadriceps ratio has not been previously described in chronic ACL deficient individuals.
  
  
  METHODS
  Eighteen subjects (36 +/- 11 years; 12 men, 6 women) with unilateral chronic ACL deficiency were recruited. Changes in activities of daily living, lean thigh volume (LTV) and isokinetic peak torque and total work capacity of both the quadriceps and hamstring muscles were investigated. The uninvolved limb served as control.
  
  
  RESULTS
  Eccentric quadriceps peak torque in the ACL deficient limb was reduced by 38% compared with the 16% reduction of concentric quadriceps peak torque. Eccentric hamstrings peak torque was reduced by 15% compared with an 8% reduction in concentric hamstrings peak torque. LTV in the ACL deficient limb was 11% smaller than the uninvolved limb (3,541 +/- 899 vs 3,161 +/- 742 cc, uninvolved versus ACL deficient limb). The relation between LTV and eccentric peak torque was stronger in the uninvolved (r = 0.82) compared with the ACL deficient limb (r = 0.66). The eccentric hamstrings/quadriceps ratio was significantly higher in the ACL deficient (0.80 +/- 0.26) compared with the uninvolved limb (0.55 +/- 0.13). However, the eccentric hamstrings/concentric quadriceps ratio was similar between ACL deficient (0.75 +/- 0.17) and uninvolved (0.77 +/- 0.20) limbs, while the concentric hamstrings/eccentric quadriceps ratio was significantly higher in the ACL deficient (0.79 +/- 0.26) compared with the uninvolved (0.50 +/- 0.14) limb.
  
  
  CONCLUSIONS
  Quadriceps and hamstrings peak torque values were significantly decreased in ACL deficient compared with the uninvolved limb. Eccentric muscle activity was affected to a greater degree than concentric muscle activity in the quadriceps muscle after ACL injury. The eccentric hamstrings/concentric quadriceps ratios were similar in ACL deficient and normal limbs, indicating that muscular co-ordination strategies may have been altered to maintain normal limb activity despite the strength losses particularly evident in quadriceps muscle function.
authors.affiliation: Department of Physiology, University of Cape Town, South Africa. agibson@sports.uct.ac.za
authors.forename: A
authors.initials: A
authors.lastname: St Clair Gibson
authors.forename: M I
authors.initials: MI
authors.lastname: Lambert
authors.forename: J J
authors.initials: JJ
authors.lastname: Durandt
authors.forename: N
authors.initials: N
authors.lastname: Scales
authors.forename: T D
authors.initials: TD
authors.lastname: Noakes
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000473:pathology; D000070598:Anterior Cruciate Ligament Injuries; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000150:complications*; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness; D018482:Muscle, Skeletal / Q000502:physiology*; D019415:Torque