Plyometrics Trainability in Preadolescent Soccer Players

What age is trainable for implementing plyometrics?  This study sought to find out whether preadolescent soccer players would benefit from combined soccer specific training and plyometric training 2x/week.  
The study design was a randomized control trial with 45 participants over a 12 week span.  The authors assigned a control group that participated in only soccer practice, while the plyometric group trained twice a week with 72hrs in between sessions. 
Speed (0–10, 10– 20, 20–30 m), leg muscle power (static jumping, countermove- ment jumping, depth jumping [DJ], standing long jump [SLJ], multiple 5-bound hopping [MB5]), leg strength (10 repetition maximum), anaerobic power (Wingate testing), and soccer- specific performance (agility, kicking distance) were measured at baseline, midtraining, and post-training.  The authors found that the plyometric group had a improvement in all speed tests (1.9-3.1% at midtraining, 3.5% at posttraining) and vertical jump tests (10.5-18.5% at midtraining and 16-23% at posttraining).  Additionally, standing long jump, multiple bounding, leg strength, agility, and kicking distance were significantly increased at mid and posttraining.  
In conclusion, what we can take away from this study is that plyometric training in combination with sport-specific training can be very effective in preadolecent athletes.  It has been debated before whether chronological age and training age plays a role in plyometric benefits and although this is only one study, it gives us some indication that plyometrics can be effective in younger populations.

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