It's time now to take a look at the timing of the natural occurring accelerated growth that are believed to be the windows of opportunity for selected motor performance abilities. In the background here, is the height velocity curve for girls that's in pink. And for boys, I've got it in blue. Now boys and girls differ in terms of the timing of their sensitivity windows because girls enter peak height velocity two years earlier than boys do. Now based on our current knowledge, the following is suggested as the optimal timing for training some of the key motor performance abilities, and we will start with Physical literacy. Physical literacy refers to the child's competence performing fundamental movement skills, such as walking, and running, and jumping, and throwing and moving through water and moving through air. And it also includes the fundamental precursors of sports skills. Such as catching on the run, kicking while running, running and then jumping over a hurdle with a three step rhythm in between. Physical literacy has a large sensitivity window from birth, all the way through to 11 to 12 years of age while the brain is enlarging to its adult size. The accelerated brain development periods begin between 6 to 8 years and 10 to 12 years are potentially lucrative periods where the fundamental motor skills appear most sensitive to training. It appears that children must acquire the mature fundamental movement patterns by the time they're 10 to 12 years old if they desire to perform at the elite level in sports as an adult. Now coordination mechanisms improve between zero to seven years of age largely due to the enhanced motor unit recruitment potential and other factors that we discussed in the previous module. Neurological development is a significant factor in improved coordination. A child's natural aerobic capacity grows significantly between 11 to 13 years for females, and 11 to 15 years for males. Training can potentially enhance the natural increase in aerobic capacity during this sensitive period by adding an additional stimulant. For the growth related changes in the cardiovascular system. And these are the capillaries surrounding the muscles, the energy production capacity of the muscle cell, and the aerobic enzymes in the muscle cell. The optimal window for trainability of strength for girls is immediately after peak height velocity coinciding with the onset of menarche. And for boys it's 12 to 18 months after the peak high velocity. Improved strength before the growth spurt is due to the effect of a better developed neuromuscular system and the subsequent coordination resulting in an enhance and more synchronous recruitment of the muscle fibers. Before puberty, the recommendation is to train strength by focusing on the neuromuscular system by using body weight, an Olympic lifting technique just using sticks, nothing else. Stimulating muscle hypertrophy becomes a priority after puberty by using the traditional strength training techniques. And for speed, for boys the first speed window occurs between ages seven to nine years. And the second window occurs between the ages of 13 to 16 years. For girls, the speed window occurs slightly differently, between the ages of six to eight years, and the second window occurs between the ages of 11 to 13 years. Now the first speed window of improvement for both boys and girls, corresponds to the brain and nervous system growth and this appears to be the best time to train the neuromuscular component of speed such as agility and quickness in change and direction. And the second window corresponds to the following two phenomenon. The first is the increase in the muscle substrates and enzymes needed for anaerobic energy which is needed for speed and is also due to the maturation of the muscle tendon sensors that improves the leg stiffness we talked about earlier and the coordination. Now, remember that coordination may decline during the early phase of the growth spurt. And if this occurs, a reduced focus on motor skill development will avoid training incorrect motor patterns. The highest natural gains in speed occurs at and around maximum height velocity, suggesting full maturation of the muscle tendon sensors has occurred. Now in terms of skill, the window for optimal skill training occurs between five to 11 years for girls and six to 12 years of age for boys. And this again, corresponds to the expansion of the brain growth towards it's adult size. According to brain theory the child will benefit from as many different skill experiences possible and this will stimulate the neuro connections allowing for greater motor learning capacity. Now, flexibility, the optimal window here is for both genders occurs between the ages of six to ten. Now you need to pay special attention to flexibility during the growth spurt to ensure that adequate tendon length while the skeleton is lengthening also occurs. And finally we'll take a look at the speed strength windows or power. And the two windows of opportunity for speed strength are, seven to nine and 14 to 15 years for boys, and six to eight, and 12 to 13 years for girls. And this is a good time to train power and acceleration skills. The two windows of opportunity for speed strength are seven to nine and 14 to 15 years for boys. And six to eight and 12 to 13 years for girls. And this is a good time to train power and acceleration skills.