The effects of proprioceptive or strength training on the neuromuscular function of the ACL reconstructed knee: a randomized clinical trial

Objectives: The purpose of this study was to determine the effects of a proprioceptive training program (PT) vs. a strength training (ST) program on neuromuscular function after anterior cruciate ligament (ACL) reconstruction. The second purpose was to establish the determinants of functional ability for the operated limb. Methods: Ten participants with unilateral ACL reconstructions were randomly assigned to one of the following 12‐week training protocols: (1) isotonic ST, and (2) PT. The outcome measures were: (1) peak torque time of the hamstring muscles (PeakTT), (2) average concentric and eccentric torques of the quadriceps and hamstring muscles, (3) one‐legged single hop for distance (SLHD), (4) one‐legged time hop (TH), and (5) subjective scores. Results: There was a significant group by time interaction effect for PeakTT ( P = 0.017). The PT group demonstrated greater percent change in isokinetic torques than the ST group at the end of the 12 weeks ( P ≤≤ 0.05). Participants in both groups demonstrated similar significant gains in functional ability and subjective scores ( P ≤≤ 0.014). Quadriceps strength is a determinant of functional ability for the operated limb ( R 2 = 0.72). Conclusions: Both training protocols influenced PeakTT. The beneficial effects of ST on PeakTT appear to be load‐dependent, while sufficient practice may be crucial in maintaining PeakTT improvements induced by PT. Proprioceptive training alone can induce isokinetic strength gains. Restoring and increasing quadriceps strength is essential to maximize functional ability of the operated knee joint.