Course:Kin366/ConceptLibrary/Plyometrics

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Movement Experiences for Children
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KIN 366
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Instructor: Dr. Shannon S.D. Bredin
Email: shannon.bredin@ubc.ca
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Important Course Pages
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Course Discussion

Overview

Plyometrics, known as jumping exercises, are traditionally used by athletes to build strength and power. It involves multiple muscular contractions and includes exercises that produce a lot of force in a short period of time such as jumping. Plyometrics include fundamental motor skills such as jumping which has a specific movement pattern and form the foundation for more specific movement activities (Gabbard, 2011). Some exercises are also classified as locomotor skills , which are movements that move an individual through space from one place to another (Gabbard, 2011). In the past, plyometrics were deemed unsafe for children due to the high stress on the body, but has since changed its views.

Exercises

Plyometric exercises are ranked by intensity. There are hundreds of possible exercises. This page will list possible plyometrics based off motor skill development and are suitable for children who have developed the appropriate skills.

Leap

Normally evident at 2 years, when child pushes off with one foot and lands on the other. Maximal height and distance not accomplished till around 5 (Gabbard, 2011). This exercise provides the element for more advanced jumping and sport skills.

Vertical Jump

A jump involving a two foot takeoff and landing with the goal of jumping as high as possible. Most children achieve mature characteristics at approximately age 5(Gabbard, 2011). A beginner jumper will show minimal crouch, arms at the middle of high guard position, slightly lean forward, and have quick flexion of the hips and knees (Gabbard, 2011).More mature vertical jump patterns include a better preparatory crouch where the hip, knees and ankles are flexed (Gabbard, 2011). It also uses an upward lift by the arms which starts and propels the child upward.

Standing long jump

This plyometric exercise involves a two foot take off and landing for horizontal distance. It is a fundamental jumping skill that involves more skill than the vertical jump because the angle of the body (Gabbard, 2011). A mature showing of this skill is usually not seen till age 6 (Gabbard, 2011). A mature execution involves a deep crouch and forward lean combined with swinging the arms forward and backward (Gabbard, 2011).Ineffective and immature jumpers may hold their arms at their side, flex their elbows, and not have much forward lean or crouch.

Hopping

Hopping is a repetition of taking off on one foot and landing on the same foot. It requires vast leg strength, balance and a controlled movement compared to other jumping movements (Gabbard, 2011). Halverson and Williams (1985) found that children could not display advanced forms of hopping till age 6 or older (Gabbard, 2011).Researchers also found that females are able to advance this skill quicker than males (Gabbard, 2011). Immature attempts at hopping are typically jerky and have little flexion in the support leg. These hops also have poor arm opposition and have little elevation. However, as leg strength and balance improves, there is better arm action, improved leg flexion, and an improved speed of movement at the hip, knee and ankle of the supporting leg (Gabbard, 2011).

Challenges

There are certain critiques and constraints against plyometrics for children and factors that can hinder the ability of a young child to be able to effectively participate in plyometrics.

Critiques/ Dangers

Plyometrics involve certain levels of physical strength, balance and flexibility to coordinate the movements. If done improperly, there is a higher risk of injuries due to the high levels of force generated. Possible injuries include joint pain, fractures, and tendinitis (Robinson, 2014). Another factor that increases the risk of injury is the volume and intensity of the exercises (Robinson 2014). A depth jump, which potentially places 10x the body weight on the individual’s joints, muscles and ligaments, is not recommended for developing children due to its intensity (McCambridge 2010). Higher level plyometric exercises should be avoided until greater strength levels are achieved. However, the myth of strength training and plyometrics stunting an adolescent’s growth is unwarranted. Data of well controlled/ designed studies show no effect on growth or epiphyseal plates (McCambridge, 2010). Nonetheless, there are constraints to plyometrics, which are factors that either facilitate or restrict development, and include individual, environmental, and task constraints (Gabbard, 2011).

Individual Constraints

Individual constraints contain structural and functional constraints (Gabbard, 2011). There may be considerable functional constraints in developing adolescents who may not have the coordination, postural stability, and strength to do certain exercises like tuck jumps or hops (Gabbard, 2011). Depending on the level of intensity of plyometrics such as depth jumps compared to standing vertical jump, there will be more individual constraints.

Environmental Constraints

Limitations in the environment that discourage the development of jumping are environmental constraints. This may include the physical environment or sociocultural factors (Gabbard, 2011). Some physical environmental constraints may include the surface of the area that the child is jumping from. Softer surfaces such as a track or grass field are better for jumping than concrete or hardwood floor. This limits the impact on the individual’s joints and ligaments. Sociocultural factors may involve the perception that plyometrics are only for athletes who are fully mature and should not be given to children. There are age-related forms of stereotyping that these activities are unsuitable for developing children (McCambridge, 2010).

Task Constraints

Task constraints are limitations that the skill itself presents (Gabbard, 2011). In plyometrics, the difficulty of the skill will affect the ability to learn the exercrise. There are hundreds of different exercises; some exercises such as squat jumps, lunge jumps and depth jumps are too difficult at a young age to do effectively. However, children frequently play on the playground, play hop scotch, skip and jump from places. These are all jumps and could be still considered a lower form of plyometrics.

Benefits

Physical Benefits

There are numerous physical and mental benefits of doing plyometrics for children if done safely and correctly. If plyometrics are introduced gradually and taught by emphasizing technique rather than intensity, it will help develop high levels of strength, balance, and postural control (Althoff & Tamporello, 2010). The flexion of the hip, knees, and ankles when landing and extending will strengthen the joints, ligaments and tendons surround the muscles as well (Robinson 2014). Additionally, the ‘stretch/shortening cycle’ involves both an eccentric and concentric contraction which produces more force and higher power inputs in the individual’s muscles (Pense 2012). This will allow the child to have grater absorbency on foot-strike and more speed. Additionally, learning new skills such as a vertical jump will incorporate more motor units and improve overall proprioception of the body (Pense 2012). Plyometrics are fun, and has been shown to be able to improve overall fitness before puberty (Althoff & Tamporello, 2010). What’s more, a study by Hamill(1994) suggest that strength training is safer for adolescents than participation in soccer, basketball, and football. Further, a plyometric jump training program can actually prevent ACL injuries (Hewett et al. 1999)

Accessibility Benefits

Plyometrics is also easily accessible and does not need much or any equipment at all. Jumping is a fundamental skill that that creates the groundwork for complex skills such as depth jumps and sprinting after maturity is reached. The muscular strength and endurance generated from plyometrics at a young age will help them become successful in sports involving power and speed such as basketball, football, volleyball, track and field and many other sports (Pense 2012).

Practical Application

Safety Precautions

Plyometrics is a valuable and effective method of developing strength, balance and power; however, it also has potential risks if volume and intensity are too high. Children are still not fully developed and are maturing physically and psychologically. Thus, a coach or supervisor should observe plyometric sessions and slowly progress their sessions (Althoff & Tamporello, 2010). Although children may jump from swings, and from slides on a playground; a structured plyometric workout is quite different than unstructured play and will need guidance from a certified coach for optimal effectiveness. Plyometric sessions may involve high eccentric levels of force which can lead to muscle soreness when initially done (Pense 2012).

Recommendations

A proper warm up is needed to prepare the child’s body for this level of eccentric and concentric work. By preparing both the central nervous system and improving blood flow to working muscles, these adolescents will be less prone to injury during plyometrics (Pense 2012). Proper progression of exercises and intensity should also be considered by the coach. Always underestimate what the adolescents can achieve when doing plyometrics. Once an adequate skill level of jumping is reached, start with low intensity drills for adolescents such as standing based jumps performed on the spot (Althoff & Tamporello, 2010). Examples include tuck jumps and stiff legged jumps with no knee flexion. The athlete can then slowly progress to other types of exercises such as jumps from standing and lateral jumps (Althoff & Tamporello, 2010). Such exercises include standing long jump, standing hop, vertical jump and side to side jumps. Adolescents should refrain from high intensity exercises such as depth jumping until full maturity due to the high level or stress and strength needed to perform such an exercise. It is important to note that jumping for the sake of jumping is not a plyometric session. Adolescents should not simply go through the motions, but should focus on the exercises at hand to be effective. Coaches should cue the athletes to react quickly after each jump and be mentally ready. This will lower the ground contact time, improve the functionality of the CNS, and subsequently activate more fast-twitch fibers (Pense 2012). Morever, to reduce the likelihood of injury in adolescents, lateral plyometrics such as side to side jumping, should be given to strengthen muscles, ligaments, and tendons of the lower extremity. Finally, there are ‘windows’ that speed should be specifically developed in an athlete’s lifetime. For females, the windows occur between the ages of 9-12 and 14-16; for males it is 7-8 and 12-14(Gabbard, 2011). Plyometrics during this time period will be especially effective during this time if volume, technique and intensity are monitored. A recommendation is for plyometrics to be done twice a week, 1-3 sets for 6-10 repetitions per exercise (Althoff & Tamporello, 2010). Fun should always be emphasized when doing plyometrics with adolescents who are still developing physically and psychologically. Children play sports because they are fun and may quit if it is not; the same applies to strength training such as plyometrics.

References

Althoff, A., & Tamporello, A. (2010). Long term athlete development. Retrieved from http://www.slideshare.net/BUAthPerformance/althoff-and-tamporello-long-term-athlete- development-4441088?qid=df4342e5-5ec2-424a-b17e- b4dea03e9b95&v=qf1&b=&from_search=11


Gabbard, C. (2011). Lifelong motor development (6th ed.) NewYork, NY: Pearson Education.


Hamill, B.P. (1994) Relative safety of weightlifting. Journal of Strength and Conditioning Research. 8(1), 53-57.


Hewett TE, Lindenfeld TN, Riccobene JV, Noyes FR. The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study. Am J Sports Med 1999;27:699-706.


McCambridge, T. (2010). Guidance for strength training in the pre-adolescent. Retrieved from http://www.slideshare.net/simon23/guidance-for-strength-training-in-the-preadolescent?qid=df4342e5-5ec2-424a-b17e-b4dea03e9b95&v=qf1&b=&from_search=15


Pense, E (2012). Plyometric Training - Is it Safe for Children? Retrieved from http://www.examiner.com/article/plyometric-training-is-it-safe-for-children


Robinson, K. (2014). Plyometrics. Retrieved from http://www.webmd.com/fitness-exercise/ guide/plyometrics-exercise-workouts?page=2