Investigating the effect of a cross-training program on the intensity and quality of activity in selected muscles of athletes with anterior cruciate ligament (ACL) injury

Abstract

Objective

The aim of this study was to investigate the effect of a two-month cross-training program on the intensity of muscle electrical activity and functional quality of selected muscles in athletes with anterior cruciate ligament (ACL) injury.

Methods

Thirty participants were divided into a training group and a control group. Muscle activity was measured using electromyography (EMG). Functional quality of the muscles was assessed using a force plate and by measuring ground reaction force (GRF) and center of pressure (COP) oscillations before and after the cross-training program.

Results

In the swing phase, electromyographic (EMG) data revealed that after a period of cross-training, the electrical activity of muscles increased. This increase was significant in the tibialis anterior (p = 0.03, d = 1.16), rectus femoris (p = 0.006, d = 1.70), and gluteus medius muscles (p = 0.01, d = 1.45). Additionally, the examination of muscle activity in the stance phase demonstrated that after the cross-training period, the intensity of electrical activity muscles increased. This increase was significant in the tibialis anterior (p = 0.001, d = 1.63), vastus medialis (p = 0.008, d = 1.07), rectus femoris (p = 0.04, d = 0.96), biceps femoris (p = 0.02, d = 1.34), and gluteus medius muscles (p = 0.002, d = 1.51).

The results of the control of movement-related data, such as ground reaction force components and center of pressure oscillations from heel strike to mid-stance, also showed that after a period of cross-training, the study samples had a significant decrease in vertical ground reaction force (p = 0.01, d = 0.93), posterior force component (p = 0.02, d = 0.96), center of pressure oscillations in the lateral direction (p = 0.04, d = 0.99), and in the anterior direction (p = 0.01, d = 1.22).

Conclusion

Cross-training or training the opposite leg has been able to which not only increases muscle activity, but also improves the quality and control of movement in injury leg.