Busch, AglajaAglajaBuschHenle, PhilippPhilippHenleBoesch, LeonoreLeonoreBoeschBlasimann Schwarz, AngelaAngelaBlasimann SchwarzBaur, HeinerHeinerBaur2024-11-192024-11-1920190949-328X10.24451/arbor.8696https://doi.org/10.24451/arbor.869610.1016/j.orthtr.2019.04.002https://arbor.bfh.ch/handle/arbor/40376Background: Studies showed altered kinematics and kinetics in anterior cruciate ligament (ACL) deficient participants, attributed to an altered sensorimotor control. However, literature on neuromuscular activity during stair ascent in patients with acute ACL rupture. Material and methods: The activity of the M. vastus medialis (VM) and lateralis (VL), M. biceps femoris (BF) and M. semitendinosus (ST) was recorded using surface electromyography (EMG) in 9 acute ACL deficient (ACL-D) (rupture 1-3 weeks prior to test) and 9 ACL intact (ACL-I) matched subjects. Participants ascended 20 times a 6-step stair at self-selected speed. The movement was divided into pre-activation (PRE), weight-acceptance (WA) and push-off (PO) phase. Comparisons were made between the deficient leg of ACL-D and the matched uninjured leg of the ACL-I, as well as between the injured and non-injured leg of the ACL-D group. Results: ACL-D showed in all muscles a reduced activation (ca. 50%, p < 0.05) compared to ACL-I during PRE. In ACLD, quadriceps activity was also reduced (ca. 50%; p < 0.05) during WA, and hamstrings displayed a lower activation (ca. 35%; p < 0.05) during PO. Intragroup comparisons showed less consistent differences in all muscles and phases. Conclusions: Altered activity during PRE indicates an alteration in the motor program (‘‘pre-programmed activity’’). Small differences in the intra-individual comparison showed bilateral consequences following ACL injury. Level of Evidence: 3enarticle