Wednesday, April 11, 2012

Plyometric Training: Effective for Young Players

Training young players can be difficult. Balancing fitness, technical and tactical training while avoiding over-training and injury can be tough. This is especially true for pre-adolescent athletes who do not yet developed the strength, coordination or fitness to handle overly intense training sessions. In the past, many have argued that there are certain types of training that should be avoided in these young players. For example, weight training in athletes younger than 15 was discouraged. However, recent research shows that if done correctly and if properly supervised, weight training can be safe and very effective for young athletes, even for pre-teens. What about plyometric training? Plyometrics can be very intense and place a large strain on joints, ligaments, tendons and muscles. As a result, it is not generally advised for young players. However, a new study conducted in Greece shows that pre-adolescents respond very well to plyometric training. Including these exercises as part of soccer training can improve strength, speed and power as well as soccer performance.

The study focused on 45 pre-adolescent, male soccer players. One of the unique aspects of the study was that the investigators used the players chronological age (average 10.5 years) as well as bone age, testosterone levels and stage of puberty development to define “pre-adolescent”. This way, they avoided having subjects who were much more physically mature than their birthdate suggested.

Approximately half of the players were placed in the plyometric training group. As part of their normal 3-times per week soccer training, they participated in plyometric training twice per week for 12 weeks. The training program was designed to limit stress and the intensity was gradually increased from a low to moderate level (in accordance with previous research). The drills consisted of single- and double-legged hops over low hurdles, lateral shuttles, skipping and footwork (ladder drills). After the first six weeks, the training began to incorporate depth jumps of increasing height. All of the drills were performed on grass to reduce landing stress and the trainers made a point to emphasize proper technique. In all, each training session lasted 20-25 minutes and was performed immediately after warm-up and before regular soccer training. The control group spent their time doing regular soccer drills while the plyometric group trained.

At both 6 and 12 weeks, the plyometric group significantly improved their sprint times (10, 20 and 30m) by approximately 2-3%. They also improved their vertical and long jump performance by more than 20% and their leg strength (back squat) by more than 25%. These changes in strength, speed and power translated into improved kicking distance and performance on an agility test. The control group also showed slight improvement in some of the measurements but the changes were far less impressive compared to the plyometric group. As a further indicator of the plyometric training program’s effectiveness, the researchers point out that nearly all of the participants improved their performance by 12 weeks.

It is important to note that no musculoskeletal injuries occurred during plyometric training. This suggests that if supervised and progressive in nature, plyometric training in pre-adolescents can be safe and effective. Clearly, common sense is needed when using a plyometric training program with young athletes. The program should be progressive, starting with low-intensity exercises before advancing to complex or intense tasks. Soft landing surfaces should be used. Proper technique should be taught, emphasized and mastered before moving from simple exercises to more difficult ones. This means that proper supervision is essential. Lastly, individual athletes should be monitored closely to insure that they are not over training or placing themselves a risk of injury.

It is also important to note a few limitations to the study. First, the design of the study didn’t require the control group to do an equal amount of non-plyometric work. Thus, it is possible that the improvements in the plyometric group resulted from added work rather than plyometrics per se. Second, females were not studied so it’s not clear of young girls would respond as well as the boys. Lastly, the participants in the study were all experienced players. While averaging 10 years of age, all had at least three years of playing experience and trained for 3-4 time per week. Recreational or inexperienced players may not respond or may be more susceptible to injury. Even taking these limitations into account, the results of the training program are significant. And it is likely that if the program were adjusted for girls and les-trained players, improvements in performance would be seen.

It is easy to see how performance changes due to plyometric training probably have important implications for performance on the pitch. Clearly speed, power, agility and kicking strength are important aspects of the game. The ability to jump, accelerate, stop and change directions is essential for success. In addition, plyometrics are an important ingredient in in the newly developed neuromuscular injury prevention programs such as the FIFA 11+. These programs generally combine with balance, agility, flexibility and core training with plyometrics to reduce the risk of ankle and knee injuries. Thus, there may be a preventative medicine aspect to plyometric training.

Given this new study, coaches now have another item in their training toolbox. Plyometric training, if used properly can be used to improve performance in young players.

Reference:

Michaildis Y, et al. (2012) Plyometrics trainability in pre-adolescent soccer athletes. Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0b013e3182541ec6