Plyometric training has been around for awhile. For the last few decades, explosive lower body efforts have been used to elicit improvements in maximal sprinting velocity in amateur and professional athletes. While this type of training is imperative for high velocity sprinting and long term athletic development in youth sports, there are some very important considerations when programming jumps into an adolescent’s training.
Studies on studies have positively linked explosive plyometric and jump training with sprinting speed in athletes of all ages. The violent triple extension and motor unit recruitment patterns of jumping have high transfer to sprinting ability. That’s certainly not up for debate here.
However, several qualities differentiate youth athletes from their older, more-seasoned peers. Testosterone production, varying limb lengths, bone structure, mental maturity, and joint integrity (in no particular order) are right around the top of the list.
We’ll start with limb length because it has serious implications regarding most of the aforementioned qualities of a young athlete. It should be pretty obvious that as an athlete grows, his/her limbs get longer (knock your head against the wall if you didn’t know that). This occurs before and after puberty and doesn’t cease until complete physical maturity. Aside from altering gross motor skills at any age, the issue can rear its ugly head in the prepubescent athlete. Longer limbs place greater stress on affected joints and underdeveloped bone structures… and they’ll only get longer as the athlete ages. Furthermore, prepubescent athletes don’t yet secrete enough testosterone yet to elicit rapid muscle growth. These varying non-linear growth patterns in the absence of increased testosterone secretion is a recipe for disaster when handled improperly during high-impact plyometric training.
The term “plyometrics” gets thrown around willy nilly these days and is often used to describe programmed jumping for training. In reality, plyometrics refers to the absorption of ground reaction forces (GRF) and the subsequent transfer of those forces back into the ground. By the truest of definitions, jumping jacks are considered more plyometric than box jumps. A classic “rule-of-thumb” prerequisite is that the athlete should be able to squat roughly 1-1.5x his/her body weight before undertaking serious plyometric training. That’s the level of strength deemed necessary to decelerate properly upon landing and absorb GRFs. By that line of reasoning, most adults don’t make the cut, let alone kids who have never set foot inside a gym! Untrained young athletes don’t need high impact plyometric training, at least not right away. They need to learn how to land properly and absorb the GRFs using active tissues (muscles) rather than passive structures (ligaments).
As strength and conditioning coaches, we have the dual tasks of improving sports performance and preventing the likelihood of injury. Injuries absolutely cannot happen inside of the weight room. Drill sound, balanced takeoff and landing technique. Begin with box jumps to minimize GRF impact on young joints. Teach proper bracing techniques so the athlete can understand the relationship between core stability and explosive movements. Make sure each athlete is capable of performing a silent “stuck” landing with zero recoil/ bounce for at least a month before moving on to legitimate plyometric training. If they can accomplish this in conjunction with effective total-body resistance training, they should be more than capable of taking advantage of their stretch-shorten cycle to receive and deliver force in repeated efforts.
Young athletes are more than capable of replicating explosive movement patterns like their older counterparts, but it has to be within reason. Plyos for conditioning–jumping on and off boxes like a maniac or 100yds of continuous broad jumps– isn’t the way to accomplish this. All forms of exercise and training come with some form of risk, no matter how small, but if you scale the program properly, these athletes will learn to recruit motor units that will translate into faster sprint times sooner, rather than later.