A 9-Year-Old is Not Half of an 18-Year-Old
  • A 9-Year-Old is Not Half of an 18-Year-Old
    Armed with a proper understanding of children's physical and mental maturation, professionals can design a safe and effective strength and conditioning program for those within the 6- to 11-year-old age range.
  • There is a relative scarcity of information regarding training children in sport, particularly among the 6- to 11-year-old age range. Moreover, the strength and conditioning coach should be aware that improvements in performance in this age group may be as much due to growth and maturation as it is to specific conditioning programs (16).

    Adult programs are too often simply copied and applied to children with little regard for growth and maturity appropriateness. There are many terms involving growth and maturation that require definition. Familiarity with several terms will begin our understanding of training this age group.

    - Growth – Measurable changes in body size (12).
    - Maturation – Refers to the youngster’s biological clock or physiological time. Maturation is usually measured relative to sexual maturation and the appearance of secondary sex characteristics (12).
    - Development – A broader concept that refers mostly to the development of competence (12).
    - Skeletal Age – Measurement of the maturity of the skeleton based on bone ossification (10).
    - Chronological Age – Elapsed time since birth in years and days (10).
    - Readiness – The match between a child’s growth, development, and readiness and the task demands of the particular activity or sport (12).
    - Puberty – The point when one is sexually mature and able to reproduce (15).
    - Menarche – Onset of maturation, not to be confused with sexual maturation or puberty (7).
    - Adolescence – Growth accelerates and secondary sex characteristics appear (7).
    - Peak Height Velocity (PHV) – Period during growth when the rate of growth is the greatest (3). Peak height velocity is often used as a marker in that children’s performance characteristics are often scaled to apply to pre-PHV and post-PHV.

    Motor Maturation

    During the age range from 6–11 years, the body grows at a relatively slow but steady rate, and movement proficiency improves steadily (10). In nearly all motor abilities, girls tend to reach their peak adaptability about two years earlier than boys.

    During this period, fundamental movements are developing and should be emphasized, such as walking, running, jumping, throwing, catching, striking, bouncing, hopping, galloping, skipping, and climbing. Balance skills, both static and dynamic, are improving as well (8,10).

    Try to allow for individualized instruction while emphasizing increased balance task difficulty. Hanging and climbing activities will be helpful to develop upper body strength and muscular endurance (8).

    Specialized movements, often found in mature sport skills, are developing near the end of this age range. Provide opportunities for practice with increasing emphasis on proper technique and form (8). Children’s interest in sport becomes intense during this period. Provide a variety of opportunities and plenty of encouragement to try harder and to try new things. Movement variety is more important during this age range than specialization (4,8).

    There are several “sensitive periods” for athletic development that occur throughout childhood. Balance skill shows a sensitive learning period from 9–10 years for girls and 10–11 years for boys, but does not reach full capacity until approximately 13 years (6).

    During the age range discussed here, there is a sensitive period for both males and females in aerobic endurance between the ages of 7 and 10 years (6). Flexibility and stretching are most adaptable during this period (14,18,19). Speed development enjoys a sensitive period during this age range as children provide a malleable nervous system for speed development, particularly ages 7–10.

    Other sensitive periods, particularly for aerobic adaptations also occur later during growth, while sprinting and speed of movement appear to be largely confined to the period before 10 years (6). With regard to speed, sprinting, and agility training, introduce high speed and more complex movements during this period, but ensure that the youngsters achieve full recovery between speed tasks (6).

    Finally, be aware of boredom by constantly varying the exercise challenges, and consider that variety can be achieved by changing the environment, starting position, direction of movement, pace, adding extra movements, changing start signals, and so forth.

    Physical Maturation

    Skull size remains approximately the same through this period until the end when the skull broadens and lengthens. The size of a youngster’s head can influence some training tasks. For example, while the child’s head is proportionately large during this age range, the arms are then relatively short.

    Thus, skills such as a backward roll are difficult to accomplish simply due to the short arms having a difficult time lifting the body high enough to clear the head as the youngster rolls backward on the floor or mat (17).

    Growth can vary enormously during this period from 7–10 years. Matching opponents should be carefully considered so that a physically more mature youngster is not matched with someone less physically mature (13).

    Growth is steady during this period which translates to increasing training loads commensurately with growth (6).

    However, consider that growth is multidimensional with psychological, social, self-confidence, social support, and other dynamics. Training load decisions should include all of the foregoing to achieve age and status appropriate demands.

    Children will grow approximately 5.1–7.6 cm (2–3 in) per year, and gain 1.4–2.7 kg (3–6 lb) per year. Peak height velocity should occur after the age range considered here, such that the rapid growth period is of limited concern. Large muscle groups are further developed than small muscles and children tend to prefer whole body movements (6).

    The strength and conditioning coach should emphasize whole body movements, using the whole-part-whole method of instruction whenever possible.

    Visual presentations and demonstrations are especially important during these years (9). Ligaments, tendons, and muscles are becoming stronger, but are not yet able to handle large external loads (6). Weightlifting should be limited with emphasis on technique using light weights. At this age, body weight is usually sufficient for development of strength. Be aware of high-impact exercises and consider using softer surfaces while monitoring fatigue closely.

    Bones are growing and epiphyseal, or growth plates, are “open” meaning still largely cartilaginous. Bone and growth plates are better at handling compression than tension or shear. Emphasize closed chain exercises when possible to avoid tensile stresses on growth areas (5).

    Muscular endurance can be developed during this period. However, large numbers of repetitions with heavy loads should be discouraged. Games and other activities involving short bursts of intense efforts followed by rest can be used to develop muscular endurance and maintain both variety and fun (6). The cardiorespiratory system is continuing to develop, but is not yet mature.

    A six-year old may have an average resting heart rate of 105 bpm, with girls usually averaging lower than boys. Absolute anaerobic power at 8 years of age is only 30–40% of that at 18 years of age (11). The smaller absolute anaerobic power values of children points to the influence of size and mass in assessment of this characteristic, but children will be lower than older athletes even in relative terms (11).

    Highly trained children will have an anaerobic threshold of approximately 75-85% of their VO2max.

    Children are better at activities with intensities below their anaerobic threshold (1,2). Try to keep muscular endurance activities below the anaerobic threshold, and therefore using the ATP-PC and fast glycolytic energy systems. Children have higher nutritional requirements than adults doing similar activities. Children can increase their basal metabolic rate much higher than an adult, supporting the idea that appropriate macronutrients are needed; both in terms of quantity and quality.


    Training children can present special challenges to the strength and conditioning coach. The idea of “age appropriateness” is simply a shorthand phrase for the old saying, “children are not just miniature adults.” Scarcely little time and documentation are provided to the strength and conditioning coach working with children.

    If you plan to simply transplant an adult program to children, please stop and reconsider. Children have different capacities than adults and need specialized programs designed for them.

    Keep in mind that the primary reason children take part in sports and other physical activities is for fun. Ensure that children are having fun while also achieving fitness and preparation for future sport activities. No one makes the pros or wins a gold medal at 10. Allow children to slowly develop so that training loads rarely reach an injury, boredom, unpleasant, and/or unfriendly threshold.


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    Sands, WA. Flexibility, in: USA Diving Coach Development Reference Manual. RM Malina, JL Gabriel, eds. Indianapolis, IN: USA Diving, 2007, pp 95-103.
    Sands, WA. Flexibility, in: Strength and Conditioning Biological Principles and Practical Applications. M Cardinale, R Newton, K Nosaka, eds. Hoboken, NJ: John Wiley& Sons, Ltd, 2010, pp 391-400.

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    About the Author:

    William A. Sands, PhD, CSCS, FACSM, C-ARS, NREMT, WEMT

    William A. Sands, PhD, CSCS, FACSM, C-ARS, NREMT, WEMT has a wealth of experience as a coach, researcher, and educator. Most recently, Dr. Sands served as Education Director for the NSCA and Director of the Monfort Family Human Performance Research Laboratory at Colorado Mesa University. He has contributed research and coaching expertise with the U.S. Olympic Committee in the fields of exercise recovery, biomechanics, and exercise physiology. Dr. Sands coaching background is in gymnastics where he produced several Olympians, more than a dozen national team members, and several World Championship Team members.

  • Disclaimer: The National Strength and Conditioning Association (NSCA) encourages the exchange of diverse opinions. The ideas, comments, and materials presented herein do not necessarily reflect the NSCA’s official position on an issue. The NSCA assumes no responsibility for any statements made by authors, whether as fact, opinion, or otherwise. 
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