Quadriceps and hamstrings peak torque ratio changes in persons with chronic anterior cruciate ligament deficiency

Study Design: Cross-sectional analytical study in which subjects served as their own controls. Objective: To assess the concentric and eccentric peak torque in the hamstr ings and quadriceps muscles, hamstrings/quadriceps amplitude ratios, and le an thigh volume differences in the involved and uninvoked limb of subjects with anterior cruciate ligament (ACL) deficiency. Background: Although the hamstrings/quadriceps ratios for concentric and ec centric activity have been studied, the more functional eccentric hamstings /concentric quadriceps ratio has not been previously described in chronic A CL deficient individuals. Methods and Measures: Eighteen subjects (36 +/- 11 years; 12 men, 6 women) with unilateral chronic ACL deficiency were recruited. Changes in activitie s of daily living, lean thigh volume (LTV) and isokinetic peak torque and t otal work capacity of both the quadriceps and hamstring muscles were invest igated. The uninvolved limb served as control. Results: Eccentric quadriceps peak torque in the ACL deficient limb was red uced by 38% compared with the 16% reduction of concentric quadriceps peak t orque. Eccentric hamstrings peak torque was reduced by 15% compared with an 8% reduction in concentric hamstrings peak torque, LTV in the ACL deficien t limb was 11% smaller than the uninvolved limb (3541 +/- 899 vs 3761 +/- 7 42 cc, uninvolved Versus ACL deficient limb). The relation between LTV and eccentric peak torque was stronger in the uninvolved (r = 0.82) compared wi th the ACL deficient limb (r = 0.66). The eccentric hamstrings/quadriceps r atio was significantly higher in the ACL deficient (0.80 +/- 0.26) compared with the uninvolved limb (0.55 +/- 0.13). However, the eccentric hamstring s/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 significantl y decreased in ACL deficient compared with the uninvolved limb. Eccentric m uscle activity was affected to a greater degree than concentric muscle acti vity in the quadriceps muscle after ACL injury. The eccentric hamstrings/co ncentric quadriceps ratios were similar in ACL deficient and normal limbs, indicating that muscular coordination strategies may have been altered to m aintain normal limb activity despite the strength losses particularly evide nt in quadriceps muscle function.