Blood flow restriction training with cross education for quadriceps muscle recovery after anterior cruciate ligament reconstruction: A prospective, randomized, controlled, single‐blind clinical trial

Abstract Purpose Recently, blood flow restriction (BFR) and cross education (CE) trainings are the options for quadriceps strength recovery after anterior cruciate ligament reconstruction (ACLR). The aim of this study was to investigate the effects of CE combined with BFR on quadriceps strength and thickness after ACLR. Methods Twenty‐four male patients [(Age: 24.9 ± 6.3 years, body mass index: 24 ± 2.3 kg/m 2 ) who had undergone ACLR with hamstring autograft were included. At 4 weeks after surgery, the patients were randomly divided into two groups (Group‐1: CE + BFR, n = 13, Group‐2: CE, n = 11). All patients had standardized rehabilitation for their reconstructed limb until 12 weeks postsurgery, and they all received CE training for uninjured limb at isokinetic system (quadriceps eccentric contraction, 60°/s 3‐set 12‐rep, 2‐days in a week) during 8 weeks. Group 2 performed the same CE procedure with BFR. Quadriceps isometric strength was measured using an isokinetic dynamometer, while the thickness of quadriceps (rectus femoris, vastus lateralis, vastus medialis obliquus) and cross‐sectional area of rectus femoris were evaluated using ultrasound pretraining (4th‐week postsurgery) and posttraining (12th‐week postsurgery). Analysis of variance was used for statistical analysis. Results Group‐by‐time interaction and the group main effect were not significant for any measured variables in both limbs ( p > 0.05). There was a significant main effect of time observed for quadriceps strength and thickness in involved and uninvolved limbs ( p < 0.001, p < 0.05, respectively). In Group 1, the limb symmetry index for quadriceps strength increased from 49.3% to 71.7%, while in Group 2, it increased from 50.9% to 75.2%. Conclusion BFR training, adapted to CE eccentric strengthening, may not be effective for quadriceps muscle strength recovery after ACLR. Further investigations with varied training protocols are needed to research the impact of BFR on CE. Level of Evidence Level II randomized controlled trial.