To evaluate neuromuscular activity during stair descent in individuals who have undergone ACL reconstruction within the first year post-surgery.
Surface electromyographic activities of the vastus medialis (VM) and lateralis (VL), biceps femoris (BF) and semitendinosus (ST) were recorded during stair descent in 31 participants following ACL reconstruction (12 females; age: 25.6±6.2 years; height: 173.5±9.1 cm; weight: 72±11.8 kg) and 31 healthy individuals (12 females; age: 26.9±6.2 years; height: 175.5±9.3 cm; weight: 70.8±10.6 kg). The stair descent movement was divided into three phases: pre-activation (PRE), weight-acceptance (WA) and push-off (PO). Linear mixed model analyses were employed to compare the normalized root mean square values for each analyzed muscle of the involved and uninvolved limbs of ACLR with the muscles of the matched involved limb of the control group (α = 0.05).
Participants with ACL reconstruction were measured at 4 time points: 3.5±0.3 (M1), 6.1±0.3 (M2), 9.3±0.3 (M3) and 12.4±0.6 (M4) months following surgical treatment, while the healthy control group was assessed at a single occasion. During PRE a significantly reduced neuromuscular activity in the quadriceps of the involved limb was observed at all measurement time points ( -86.1 β -68.7; 0.0001 p 0.01), accompanied by a significant decline in the VM of the uninvolved limb at M1 (β = -55.7; p = 0.02) and significantly elevated neuromuscular activity in the ST of the involved leg at M4 (β = 55.6; p = 0.004) compared to the control group. Results during WA demonstrated a significant reduction in quadriceps activity across all measurement time points ( -144 β -87.5; 0.0001 p 0.01), accompanied by a significant decline in the VL of the uninvolved limb at M2 (β = -83.9; p = 0.04) and significantly increase in neuromuscular activity in the ST of the involved leg at all measurement time points (14.4 β 42.9; 0.001 p 0.03). During PO significant reduction in the quadriceps of the involved limb was observed at M1 and M2 (-135.7 β -108.7; 0.003 p 0.02) and in the BF of the involved limb at M1 (β = -31.9; p = 0.04).
Neuromuscular alterations are present early following ACL reconstruction and cannot be resolved during rehabilitation. Inconsistent findings were found in the uninvolved limb.
Neuromuscular training and motor learning principles should be incorporated into rehabilitation content, with the objective of enhancing dynamic knee stability. Moreover, a comprehensive reassessment of the existing return to sports testing protocols, with a particular emphasis on the integration of neuromuscular assessments, may be essential to minimize the risk of re-injuries.
Stair descent
Electromyography
