Developmental Windows or Sensitive Periods
It is important to have a plan for training the developing athlete from a very young age that will progress them appropriately as they age. Piaget identified four distinct stages of development in children. The sensorimotor phase, the preoperational thought phase, the concrete operations phase (7 to 11 years), and the formal operations phase (beginning at 11 years). At the preoperational phase learning occurs via physical exploration rather than a cognitive approach. Cognitive perception begins to develop in the formal operations stage but it is more of a stimulus–response style. Once the formal operations phase is reached, a more systematic problem-solving approach begins to take hold.
“Postural muscle activity is genetically pre-determined and occurs automatically in the course of CNS maturation….The quality of verticalization during the first year of life strongly influences the quality of body posture for the rest of a person’s life”. The stage from 2 to 7 years has been called the fundamental movement phase by Gallahue. In this stage the child explores, “a variety of stabilizing, locomotor and manipulative movements….” This is then followed by the specialized movement phase from 7 to 11 years where FMS are honed and progressed to incorporate more complex skills. A few commonly agreed upon developmental landmarks according to McMorris and Hale are as follows:
• By 6 years of age, normal children are capable of jumping, catching, skipping, throwing, and balancing
• At 6 years, a child can strike a stationary object but has difficulty with a moving object due to immature eye–hand and foot–eye coordination
• Boys perform better than girls at most skills, except balance
• Girls are more flexible than boys
• Perceptual skills such as visual acuity and depth perception reach maturity around the age of 12 years
• Physical development in 11- to 13-year-olds varies greatly
• Children reach adolescence at different ages 1
Sensitive periods are best defined as “windows of opportunity and vulnerability in the skill acquisition process”. In Chinese and Korean immigrants whose first exposure to English occurred between the ages of 3 and 39 years of age, it was shown that the ages between 3 and 7 were the most sensitive, so much so that their English speaking fluency was indistinguishable from native English speakers. Similarly, proficiency in high levels of fine motor skill necessary for music is best achieved if trained by age 7. For swimming the optimal or most efficient age to begin learning has been shown to be 5.5 years. Simonton reported that the greatest composers who started music lessons at a younger age took less time to hone their skills. In other words, the training was more efficient. The above insights should be tempered by research showing sensitive periods are not brief, sharply defined, or irreversible. Some confusion in the literature exists, because the terms critical period and sensitive period are both used.
Critical periods should narrowly be applied to developmental changes that occur in the neural circuitry underlying behavior and are more fixed. Sensitive periods refer to temporal phases where environmental input can have a potent effect on habitual behaviors. The question of when to train specific motor skills is a“holy grail” in the early training of youth athletes. However, according to Anderson et al. “our understanding of when children are best prepared to profit from specific experiences and how to create that preparation is poor.” Nonetheless, the authors state, “motor skill learning must ultimately be considered within a developmental context if it is to be fully understood.”