The effects of motor imagery and action observation-based plyometric training on muscle architecture and jump performance of adolescent soccer players.

Objective: Lower limb muscle-tendon injuries are the most common injuries in adolescent soccer players. The primary aim of this study was to examine the effects of motor imagery and action observation-based (MI+AO) plyometric training (PT) on the pennation angle (PA), muscle thickness (MT) and fiber length (FL) of the vastus lateralis (VL) and biceps femoris long head (BFlh). The secondary aim was to evaluate the effects of training on single leg jump performance. Methods: Thirty-six healthy adolescent soccer players (age: 13.91±1.05 years, height:162.22±10.20 cm, weight: 52.09±8.33 kg) were randomly assigned to PT (n=17) or control (n=19) groups. Athletes in both groups continued their routine training programs. PT group also participated in 3 sessions of training per week for 8 weeks. Athletes watched the prepared videos and imagined jumping. Muscle images were taken using the ultrasound probe. Outcomes were assessed at baseline, 4, 8, and 12 weeks. Results: There was no significant change in the muscle architecture parameters in the control group during 8 weeks (p>0.05). The dominant (mean difference=2.40±3.45°, p=0.01) and non-dominant side (mean difference=3.32±3.75°, p=0.01) VL PA was higher in the PT group at week 4 compared the baseline. Similarly, there was a significant increase in dominant side VL MT (mean difference=0.15±0.19 cm, p=0.03), nondominant side VL MT (mean difference=0.24±0.23 cm, p=0.01), and dominant side BFlh MT (mean difference= 0.21±0.31 cm, p=0.03). Both sides jump performance was significantly better in the PT group at weeks 4 and 8 compared to baseline (mean difference=16.71±11.76 to 22.88±12.19 cm, p<0.01). In time x group interactions, non-dominant side VL PA (p=0.03) and MT (p<0.01), dominant side BFlh MT (p=0.04), and both side jump performance (p<0.01) were higher in the PT group. Conclusion: This research provides the first evidence that MI+AO PT improves muscle architecture. It is recommended that future research be conducted in injured athletes and using neuroimaging tools. [ABSTRACT FROM AUTHOR]