A Randomized Controlled Trial of Eccentric Versus Concentric Cycling for Anterior Cruciate Ligament Reconstruction Rehabilitation

Background: Persistent strength and biomechanical deviations remain after anterior cruciate ligament reconstruction (ACLR). Eccentric training may reduce these and associated reinjury or osteoarthritis risks. Hypothesis: For male patients who have undergone ACLR, eccentric training is more effective than concentric training at improving knee flexion angle and other biomechanical deviations, as well as strength and patient-reported outcomes, using a matched perceived exertion dose. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 26 men, 10-16 weeks after hamstring tendon graft ACLR, were randomized to an eccentric training group or a concentric control group. Both groups trained 3 times a week for 8 weeks using the same isokinetic cycle ergometer in a matched studio environment. Exercise dose was matched in training frequency, time, progression, and intensity using a target rating of perceived exertion. Baseline and follow-up testing included questionnaires, dynamometer strength testing, and walk/run gait analysis. Results: Eccentric training increased knee (+2.1°; P = .022) and hip (+2.1°; P = .010) flexion angles more than concentric training but not more than the minimal clinically important difference of 3°. Very large asymmetries in baseline knee abduction moment (walk, −0.10 N·m/kg/m; run, −0.54 N·m/kg/m) had not changed in either group by follow-up. Knee valgus angle effects were mixed. Tibial rotation angle increased in both groups, but concentric training was more effective at promoting symmetry (P < .001). Both groups had similar increases in affected limb quadriceps strength and knee flexion moments during walk/run gait (by 20% to 33%). Hamstring strength increased in the eccentric group (+15.4%) but not the concentric group. Eccentric group limb forces were 33% to 70% higher than those of the concentric group, with a lower heart rate. Both groups had low pain scores throughout. Conclusion: For rehabilitation after ACLR, progressive eccentric cycle training was not more clinically effective than concentric training at a matched perceived intensity dose in male patients. This can guide exercise prescription for reducing gait and strength deviations of these patients. Registration: PACTR201602001449365 (Pan African Clinical Trials Registry), NHREC 4344 (South African).