Labanca L, et al. - In this study, 12 individuals with anterior cruciate ligament reconstruction (ACLR) who took part and 12 healthy controls were exposed to 10 either unpredictable or predictable perturbations of the knee prior to ACLR (T1), two months (T2) and six months (T3) following surgery. Experts intend to examine compensatory and anticipatory quadriceps activation (CQA and AQA) before and after anterior cruciate ligament reconstruction (ACLR) utilizing hamstrings graft. In ACLR, comparison with controls at T1 for vastus lateralis (VL)(105 ± 25 vs 57 ± 9 ms), rectus femoris (RF) (102 ± 23 vs 56 ± 9 ms) and vastus medialis (VM) (107 ± 24 vs 66 ± 16 ms), at T2 for VL (68 ± 14 vs 55 ± 10 ms) and at T3 for VL (105 ± 22 vs 58 ± 7 ms), RF (102 ± 22 vs 58 ± 12 ms) and VM (106 ± 20 vs 63 ± 8 ms), latency of CQA was delayed. Therefore, CQA was delayed after ACLR with hamstring graft and shall be addressed by post-surgical improvement.