Abolfazl Khouri1, Nader Rahnama2, Hasan Daneshmandi3, Mohammad Hossein Alizadeh4
Background: the present study aimed to investigate the effect of a corrective exercise protocol on knee flexion angle and electromyographic activity of lower extremity muscles with ACL injury prevention approach.
Method: The present study was quasi-experimental and conducted by pretest-posttest design with two control and experimental groups. 30 healthy male weightlifters were selected as samples according to the inclusion criteria and randomly divided into two experimental and control groups. The experimental group performed the exercises 3 times per week and for 6 weeks. electromyographic activity of muscles and kinematic data of both groups were evaluated before and after implementing the exercises protocol. Dependent t-test was used to compare the results within a group and independent t-test was used to compare the results between the groups at the significance level of 0.05.
Results: the results of statistical tests showed that in the experimental group, electromyographic activity of Vastus lateralis, Vastus medialis, Biceps femoris and Semitendinosus muscles significantly increased in response to corrective exercise program (P0.05) and no significant difference was observed in the control group (P0.05). After performing the exercises, significant difference was observed between the two experimental and control groups in electromyographic activity of muscles (P0.05). Also, significant reduction in the co-contraction level of quadriceps/hamstring ratio (Q: H) in the experimental group was observed to the control group (P ≤ 0.05). Significant difference was observed between the two groups in the knee flexion angle and the results showed a significant increase in knee flexion angle in the experimental group (P ≤ 0.05).
Conclusion: the results of the present study showed that using the mentioned exercise protocol can establish balance in Q:H ratio and as its result, knee flexion angle increases. Accordingly, it is recommended to use combined exercises in ACL injury prevention programs.
