ADOLESCENT GROWTH AND MOTOR DEVELOPMENT Larry D. Isaacs

§10.1 DEFINING ADOLESCENCE  Most frequently, adolescence has been defined as a transitional period between childhood and adulthood.  According to the World Health Organization, adolescence would be expected to occur between the chronological ages of 10 to 18 years.  A more realistic global chronological age range would be in the vicinity of 8 to 19 years of age for girls and between 10 to 21 years of age for boys.

§10.2 THE ENDOCRINE SYSTEM: HORMONAL INFLUENCES ON AGENTS OF BIOLOGICAL CHANGE  The hallmark of pubertal initiation is the appearance of gonadotropin releasing hormone (GRH)  It is the hypothalamus - pituitary - gonadal axis which is responsible for most of the biological hallmarks associated with adolescence.

§10.3 SOMATIC PATTERNS OF CHANGE IN BODY SIZE AND IMPLICATION FOR MOTOR PERFORMANCE Stature  One of the most profound somatic changes to occur during adolescence is the rapid acceleration in stature.  Brought about by the many hormonal changes described earlier, this 2.5- to 3-years of rapid growth is referred to as the adolescent growth spurt.

 The term adolescent awkwardness has been used to refer to a period during the growth spurt  peak height velocity (PHV); maximum rate of growth in height that is accompanied by a temporary disruption in motor performance

Weight  Adolescence can bring about dramatic increases in body weight.  During the first 3 years of this period, boys add about 20 kilograms to their body weight and girls add about16 kilograms,

 Body mass index (BMI) :  This measure is valuable because it is related to body fatness and future health risks, including increased incidence of cardiovascular disease, diabetes, hypertension, hypercholesterolemia, and certain cancers.  BMI cannot be used to determine percentage of body fat.

Body Proportions During adolescence not all body segments growth at the same velocity nor do they grow in an absolute comparative manor. The comparison of biacromial breadth (shoulder width) to bicristal breadth (hip width). Changes in sitting height (trunk length) as a ratio with stature Arm length also appears to influence motor performance.

Muscular Strength Development  prior to puberty boys are about 10 percent stronger than girls 。  Gender differences in muscular strength become most apparent after puberty  During this time of development, boys become leaner and young girls begin to develop more body fat.

§10.4 DETERMINING DEVELOPMENTAL AGE AND MATURATIONAL STATUS Developmental age, however, is by far a better indicator of maturity than is chronological age. A set of predictable physiological parameters  Skeletal age -the most widely accepted assessment procedure for determining stage of maturation

 Age of menarche is an important event useful for estimating level of maturation, even though the event does not generally occur until relatively late in puberty.  Genitalia development is an ancillary method for rating level of biological maturation.

Maturation: Interrelationship with Motor Performance  Researchers recognize that physically advanced people generally perform selected motor tasks more proficiently than their less mature counterparts.  Early maturation, with its concomitant size and strength advantages, constitutes an asset positively associated with success in several sports

 Once the late-maturing person has reached a state of postpubescent development, he is generally larger and has more athletic success simply because he has had a longer growth period.