Quantifying The Relationship Between Quadriceps Strength And Aerobic Fitness Following Acl Reconstruction

Abstract

PURPOSE: Investigate the relationship between performance measures and quadriceps strength in individuals with ACL reconstruction (ACLR) and healthy controls. METHODS: Thirty-three individuals with ACLR (22F/11M, 19.9±2.2 years, 68.3±10.9 kg, 170.4±8.4 cm, 22.7±23.3 months post-surgery) and 29 healthy individuals (18F/11M, 20.1±1.5 years, 70.0±9.9 kg, 172.7±8.7 cm) completed isokinetic quadriceps strength testing using a Biodex dynamometer at 180 degrees/sec on both legs then completed vertical jump (VJ) testing with and without countermovement (NCMJ) on a jump mat. All participants completed an incremental treadmill test to determine maximal oxygen consumption testing (VO2max). Initial running velocity was self-selected and increased 0.5mph every 2 minutes until volitional fatigue. Knee extensor torques and VO2max were normalized by mass. Bivariate Pearson’s correlations were calculated between strength and performance variables. Significant correlations were retained for a regression analysis. RESULTS: In ACLR, peak torque was correlated with VJ (r = 0.43, P = .012), NCMJ (r = 0.44, P = .011), and VO2max (r = 0.52, P = .002). The only variable retained in the regression model was VO2max, which explained 26.7% of the variance in strength. In healthy individuals, peak torque was correlated with VJ (r = 0.72, P < .001), NCMJ (r = 0.62, P < .001), and VO2max (r = 0.55, P = .002). Two variables were retained in the regression model, including VJ (R2 = 52.2%) and VO2max (R2 = 6.8%) which together explained 59.0% of the variance in strength. CONCLUSIONS: Quadriceps strength was associated with a VJ, a powerful quadriceps movement, in healthy individuals, while strength in individuals with ACLR was associated with aerobic fitness. Although VO2max was a significant predictor of strength after ACLR, it explained a small amount of variance which suggests other factors contribute to strength after ACLR.