Chapter 15 Adolescent Growth, Puberty, and Reproductive Maturity © Gallahue, D.L., & Ozmun, J.C.. Understanding Motor Development. McGraw-Hill

Key Concept The Transition From Childhood to Adolescence Is Marked by a Number of Significant Physical and Cultural Events That, in Combination, Contribute Markedly to Growth and Motor Development

Adolescence Defined Biologic considerations (earlier start) Cultural considerations (later finish)

Adolescent Growth Genotype & Phenotype (genetic & environmental growth potential) Genotype (biology determines: final body measures, skeletal & sexual maturation, & body type) Phenotype (growth potential: body weight, skin folds, circumferences)

Height Adolescent growth spurt - Males (average start; Age 11, peak; 13, taper; 15, finish; 18) - Females (average start; Age 9, peak; 11, taper; 13, finish; 16) - Peak velocity (average 1 yr. gain 6-8 in (15-20cm) - Genotype drives height gain (figure 15.1)

Height (Cont.) Peak height velocity - Males (coincides with secondary sex characteristics) - Females (coincides with secondary characteristics but precedes menarche) Predicting adult height (table 15.1) Steroids and stature

Weight Peak weight velocity (due to >muscle mass, fat mass & ht.) - Males (close match with peak ht., Age 10 = 55% of final adult wt.) - Females (> increase in fat mass, by age 10 = 60% final adult wt.) - Phenotype drives weight gain (i.e. diet, exercise, lifestyle)

Heart and Lungs Heart (size >by ½) - Female resting rate = 62-63bpm Lungs (size >by ½) - Respiration rate decreases - Vital capacity increases, but is much greater for males

Pubescence Puberty: Onset of sexual maturation. (begins with growth spurt & secondary sex characteristics,culminates with reproductive maturity) - Females (average onset: age 9, early <8, late >13, secular changes) - Males (average onset: age 11, early <9, late >14, secular changes?) Culminating event (females = menarche, males = ejaculation)

Sexual Maturity Female menarche (USA average age; 12.5, Blacks; 12.1, Whites; 12.9, Asians; 12.3) - Early menarche (why? i.e. what is the mechanism) - Late menarche (why? i.e. what is the mechanism?) Sequence of puberty (table 15.2)

Female Sequence of Puberty Breast development (table 15.3) Pubic hair formation (table 15.3) Rapid height gains Axillary hair formation Menarche Acne

Male Sequence of Puberty Testicular growth (table 15.4) Pubic hair formation (table 15.4) Rapid height gains Axillary hair formation Facial hair formation Deepening of voice Acne

Pace of Puberty Pace (earlier onset, but same duration) What triggers gonadotropic hormones? - Genotype - Stress - Diet & nutrition - Exercise & percent body fat - Chronic illness & disease - Environmental toxins

Maturity Assessment Using Tanner stages - Advantages (valid, reliable, objective) - Disadvantages (embarrassment, social-cultural mores) Using subjective clues (height, facial & axillary hair, voice)

Concluding Concept Adolescent, Growth, Maturity, and Sexual Maturation Are Complex Processes Requiring Sensitive, Understanding and Nurturing Adult Support