One hundred and six patients after ACL reconstruction were randomized to isoinertial + conventional rehab (n=53) or conventional rehab alone (n=53). The primary outcomes were lower-limb muscle power (concentric/eccentric); secondary outcomes included endurance, isometric strength, and balance. Outcomes were measured at baseline and six weeks using a flywheel ergometer protocol. Overall, both groups improved in concentric/eccentric power, isometric strength, and balance; endurance improved only with the isoinertial-augmented program. Between groups, gains in eccentric power favored isoinertial training, while concentric power, isometric strength, and balance were similar. These findings suggest adding flywheel-based isoinertial work meaningfully augments eccentric power (and endurance within-group) beyond standard rehab in early post-operative ACL care.