Human Growth and Development Study Guide

Overview of Human Growth and Development

• Fundamental Premise: The human body is in a state of constant change, manifesting most rapidly after the onset of puberty. Key factors influencing these changes include daily nutritional intake and the type/amount of physical activity.

• Core Quote: "We are guilty of many errors and many faults, but our worst crime is abandoning the children, neglecting the foundation of life. Many of the things we need can wait. The child cannot." — Gabriela Mistral, $1948$.

• Importance of Education: Understanding growth and development allows practitioners to recognize how individuals respond to exercise demands across different life stages, acknowledging that children and adults learn new skills at varying rates.

The Four Key Components of Human Growth and Development

• Physical Development: Involves the growth and development of the body’s muscles, bones, energy systems, and nervous system.

• Cognitive Development: Refers to an individual’s capability to interpret and process information, alongside the introduction and establishment of self-concept or self-awareness.

• Social Development: Focuses on the development of relationships with peers, friends, relatives, adults, and members of the "outside world."

• Emotional Development: Refers to the ability to manage and regulate emotions including motivation, pleasure, empathy, fear, anxiety, and anger.

Conceptualizations of Age

• Chronological Age: Age measured strictly in years, months, and days; this is the standard societal use of the term.

• Skeletal Age: Determined by the physical maturity of the skeleton based on the degree of ossification (the conversion of soft tissue into hard bone). This is typically measured via an x-ray of the hand and wrist. Factors such as nutrition, diet, disease, and major bone injuries can cause skeletal age to lag behind chronological age.

• Developmental Age: Includes the interaction between physical, cognitive, social, and emotional development. It is expressed through an individual’s ability to perform specific tasks.

Patterns and Sequences of Physical Growth

• Cephalocaudal Sequence: Describes growth progressing from the head first, followed by the trunk, and then the extremities. Development occurs earliest in the brain and skull, followed by the heart, lungs, and other organs, and finally the limbs.

• Proximodistal Sequence: Describes movement patterns originating close to the center of the body developing earlier than those originating farther away.

• Stability and Movement:

  • Because the head develops fastest, an infant’s center of mass is higher, leading to relative instability (reason for crawling before walking).

  • As muscles in the legs, arms, back, and neck develop, the center of mass moves closer to the ground, increasing stability.

  • Humans typically become proficient in locomotor skills (running, jumping, hopping, skipping) before manipulation skills (throwing, kicking, dribbling).

Observable Growth Patterns and Critical Periods

• Growth Spurts: Height increases rapidly from birth to age $3$, and jumps again during teen years.

• Peak Height Velocity (PHV):

  • Girls: Reach PHV at approximately age $12$, with an average increase of $8\,cm$ per year.

  • Boys: Reach PHV at approximately age $14$, with an average increase of $10\,cm$ per year.

• Critical Periods: Phases such as the transition from childhood to puberty involve hormonal changes where bones are more susceptible to becoming denser. Healthy bone development at this stage helps prevent osteoporosis later in life.

The Four Main Stages of Physical Growth

• 1. Infancy/Toddler (Birth to $2-3$ Years):

  • Period of the most rapid growth relative to all other stages.

  • Birth weight typically doubles in $6$ months and triples in $1$ year.

  • Weight increases by approximately $300\,$ and height by $50\,$.

  • Brain weight increases rapidly; bones harden considerably.

  • Milestones: By age $2$, most master walking and begin running/kicking. By age $3$, children can balance on one foot and ride a tricycle.

• 2. Childhood ($4-10$ Years):

  • A relatively long period maintaining a rapid growth rate.

  • Mid-childhood ($6-10$ years) is a stabilizing period where bone and tissue growth align, creating a base for motor skills.

  • Requires unstructured, imaginative play for healthy development.

• 3. Puberty/Adolescence ($11-18$ Years):

  • Growth speeds up; marked by a pronounced growth spurt (most significant since infancy).

  • Usually occurs between ages $10-15$, typically earlier in females.

  • Pituitary gland secretes hormones causing sex organ development and capabilities for reproduction.

  • Average age for girls is $12-13$; average for boys is $13-14$. Girls are often taller/heavier than boys from ages $10-13$.

• 4. Adulthood ($18$ Years and Older):

  • Most physical growth is complete.

  • Potential changes: Weight gain, reduced oxygen capacity, increased blood pressure, increased resting heart rate, and weakening of stress-bearing joints (knees, hips).

  • CSEP ($2011$) Guidelines: Adults/seniors should accumulate at least $150$ minutes of moderate-to-vigorous aerobic activity weekly, plus strength activities at least $2$ days per week.

Jean Piaget’s Four-Stage Model of Cognitive Development

• Stage 1: Sensorimotor (Birth to $2$ Years):

  • Intelligence demonstrated through motor activity without symbols.

  • Knowledge based on immediate experience; development of object permanence (memory to recall objects) and early language.

• Stage 2: Pre-operational ($2-7$ Years):

  • Intelligence through symbols (letters, numbers, pictures).

  • Language, memory, and imagination grow significantly.

  • Linear thinking (start to finish) is possible, but reversed processes are not. Highly egocentric.

• Stage 3: Concrete Operational ($7-11$ Years):

  • Logical thinking develops; ability to solve hands-on problems.

  • Reversibility (operational thinking) is mastered. Egocentric thought decreases; empathy increases.

• Stage 4: Formal Operational ($11-15$ Years):

  • Ability to solve abstract problems using logic and symbols.

  • May return to egocentric patterns early in this stage.

Physical Activity and Brain Health

• Neuroplasticity: Cognitive research indicates brains can be rewired and reshaped.

• Biological Benefits of Aerobic Exercise:

  • Increases Brain-Derived Neurotrophic Factor (BDNF) for brain cell growth.

  • Stimulates neurogenesis (birth of new neurons).

  • Enhances brain plasticity by mobilizing gene expression.

  • Prevents brain tissue loss in aging adults.

• Key Research Findings:

  • Davis & co. ($2007$): $40$ minutes of daily aerobic exercise improved executive function in overweight children.

  • $2010$ Study: Physically fit children ($9-10$ years old) had larger hippocampi and performed better on memory tests.

  • Davis & co. ($2011$): $13$ weeks of aerobic exercise improved math skills and