DPT571: Lifespan Mobility & Motor Development

• The lecture discusses mobility through the lifespan, focusing on theory, influences, and the emergence of typical development, as part of the DPT571 Movement Science course in Spring 2024, taught by Dr. Pelletier.
• This course aims to provide the theoretical basis for typical motor development, state the influences on the development of humans, and understand the sequence of early motor development, including embryology, reflexes, and postural control.
• "Those who see things grow from the beginning will have the finest view of them." - Aristotle (384-322 BCE)

Developmental Theories

• Neural-Maturational
• Cognitive/Behavioral
• Dynamic Systems

Neural-Maturational Theories

• This theory follows a hierarchical structure.
• Key figures in this theory include Gesell, Bayley, and McGraw.
• It places emphasis on the normal sequence of development.
• Functional behaviors evolve as the central nervous system (CNS) matures.
• The CNS is seen as the driving force in development.

Behavioral Theories

• Major contributors to this theory are Pavlov, Skinner, Bandura, and Piaget.
• Changes in behavior occur as a result of environmental stimuli that reinforce specific actions, either positively or negatively.

Dynamic Systems Theories

• The ecological approach is a component of it
• Key figures include Bernstein, Thelen, Horak, Heriza, Shumway-Cook, and Woollacott.
• Development is nonlinear and influenced by both intrinsic and extrinsic factors.
• The process of development is emphasized over the end product.
• Contributing factors include genetics, nutrition, ethnicity, prenatal care, socioeconomic status, and trauma.
• Multiple systems work together to influence behavior.
• Developmental change is not a series of discrete stages but a series of states, varying in stability.
• No single element determines behavior or controls developmental change.
• Behavior is affected by individual, environmental, and task constraints.
• While Dynamic Systems theories are favored by many therapists, the predictable pattern of infant development makes maturational theories valuable.

Development of Early Reflexive and Postural Control

• Spontaneous Movements/Reflexes are categorized into:
  • Spontaneous Movements
  • Primitive Reflexes
  • Postural Reactions
  • Locomotor Reflexes

Spontaneous Movements

• These movements do not result from specific stimuli.
• They are nonspecific and generalized.
• Thelen (1985, 1995) studied spontaneous kicking in infants.
• Kicking patterns are rhythmical, not random.
• The ankle, knee, and hip move cooperatively.
• The timing resembles that of an adult step.
• Kicks are similar but not identical, with timing variability.
• Joints move in unison rather than sequentially.
• Co-contraction exists during infant kicking.
• Adult gait involves alternating flexion and extension.
• By the end of the first year, increased flexion/extension is observed.

Primitive Reflexes

• Up to 70 have been described.
• There is some controversy over the use of the term "primitive."
• These reflexes are important for survival during early infancy.
• Responses to external stimuli are specific and localized.
• The same stimulus elicits the same response each time.
• Examples include rooting, sucking, withdrawal, Moro, grasp, Babinski, ATNR, and STNR.
• Asymmetrical tonic neck: When the head is turned to one side, the arm and leg on that side extend.
• Symmetrical tonic neck: When the head is extended, the arms extend and the legs flex.
• Doll-eye: When the head is flexed, the eyes look up.

Postural Reactions

• Help infants automatically maintain posture in a changing environment.
• Types of reactions include:
  • Labyrinthine Righting
  • Optical Righting
  • Pull-Up
  • Parachute
  • Propping
  • Neck Righting
  • Body Righting

Locomotor Reflexes

• Include stepping, swimming, and crawling.

Role of Reflexes in Development

• Prenatal explanations include:
  • Structural—wired for survival
  • Functional—for fetal positioning.
• Postnatal explanations explain the role of reflexes in volitional movement.
• McGraw (1943) suggested that reflexes need to be inhibited by the CNS before voluntary movement can occur.
• Zelazo et al (1972) found that reflexes and voluntary movement are related.
  • Eliciting the stepping reflex daily for eight weeks results in
  • Increased stepping reflex and earlier onset of walking.
• Thelen (1983, 1991, 1995) showed that changing constraints can alter reflex integration.
• Increased limb weight without increased muscle strength may explain reflex integration.
• Adding weight to the limbs of 4-6 week old infants decreases stepping reflex.
• Older infants in chest-deep water show increased stepping reflex.
• Seven-month-old infants without reflex stepping can take steps on a treadmill. -Differing constraints, not maturation, may account for reflex integration.

Influences on Human Development

• Motor development includes internal, external, and maturation factors. Internal: heredity/genetics External: environmental, experiences, culture Maturation

Culture

• A system of learned behavior patterns is acquired through social interaction, shared by others, and influences the ability to interact.
• Encompasses ethnicity, and race.
• It greatly influences development.
• Environmental and cultural factors have motor development.
• Cultural/ethnic beliefs, traditions, and maternal handling affect motor skills
• Postural adjustments/control and maternal expectations, as well as social variations influence style of parents
• Survival, discipline, and the value placed on equipment and care affect it
• Social learning and socialization are critical for motor development.
• Motor experiences are vital for skill development and increased proficiency.
• Social and personality development influences include gender-typing, cultural aspects, moral implications, and family/peer issues.
• Socializing agents include family members, peers, teachers, and coaches.
• Social situations impacts it, such as environment, toys.
• How this impacts the movement system includes:
  • Endocrine
  • Nervous
  • Musculoskeletal
  • Integumentary
  • Pulmonary
  • Cardiovascular

Typical Motor Development - Embryology

• The stages of prenatal/postnatal motor development include:
  • Germinal Period at 0-2 weeks
  • Embryonic Period at 2-8 weeks
  • Fetal Period at 8-40 weeks
  • Infant development at Birth-2 years
  • Child development at 2 years-Adolescence
  • Adolescent development during the transition to maturity

Embryonic Period

• Lasts for six weeks.
• Organogenesis occurs, defining the cells.
• At three weeks, cells differentiate into three layers:
  • Ectoderm (outer)
  • Mesoderm (middle)
  • Endoderm.
• Endoderm forms the digestive/respiratory systems.
• Mesoderm forms the muscles, skeleton, circulatory, and reproductive systems, as well as the dermis.
• Ectoderm produces the CNS, PNS, eyes, ears, and outer skin.
• By the end of eight weeks, the embryo is distinctly human in appearance.
• The head becomes more round and erect but remains large.
• The neck becomes established, eyelids become more obvious, and the auricles of the ears begin to take shape.

Fetal Development

• Fetal Period: 8-40 weeks.
• Weeks 9-12: Sensory organs develop, with rapid fetal growth and increased movement.
• Weeks 13-16: Breathing and swallowing enhance tactile stimulation, supporting growth and coordinated limb movements.
• Week 20: Myelinization begins, and the fetus starts turning around.
• Week 28: Retina and light sensory system are developing.
• Week 32: Taste sensation is operable.
• Weeks 38-40: Myelinization continues through full term.

Skeletal Development

• Bones arise from the mesoderm layer.
• Skeletal system portions form during the first few weeks postconception.
• By the end of the embryonic period, the skeletal pattern has formed in cartilage and connective tissue, and ossification starts.
• Ossification consists of intramembranous and endochondral types.
• Replacement in bones happens to bones of different bony tissues.
• Two forms the skull and the bones of irregular shapes.
• 1 Formed like that form tissue membrane by depositing tissue.
• Most bones this in cartilage models that form.
• After conception of vessels and periosteum the surface infiltrates bloods
• 12 weeks, blood vessels increase and cartilage disintegrates

Specific Embryological Development of Limbs

• Limb buds appear at week 4.
• Upper limbs begin development 1-2 days prior to lower limbs.
• Buds consist of mesenchyme derived from mesoderm, covered by ectoderm.
• Ends of the bud develop into paddle-like hand or foot plates.
• Digital rays form in hands by the end of the sixth week, in feet by the seventh week.
• Apoptosis which occurs for the completion of digits occurs by of the eighth week.
• In the seventh week limbs will extend and rotate in opposite directions.
• Homogulous bodyparts are Radius/Ulna homologous to Tibia/Fibula; Great toe to Thumb
• Dermatomes are the During fifth week of development, peripheral nerves extend from limb plexuses into the limb bud

Muscle Development

Most muscle develops from the mesoderm The skeletal, smooth (gut and derivatives), smooth (pupil mammary, and sweat glands), and cardiac are all different types The steps for primary and secondary muscle are all found in figure 7-7

• Typical Developmental Sequence showcases typical fetal posture includes: Holds chin up, Holds chest up, Assists alone and assisted , Crawls and Walks.
• To properly understand this concept is important for multiple reasons including: This assists in progressing in Pediatric and Adult and assists with developmental impairments.
• As of current, it has been found this process is more than just the milestones, also taking the skill into skill.
• "Normal" varies individual-to-individual while "typical" sequence, it is important to note that development generally exhibits variable.

Important Caveats

• Development is unique from birth (childhood), genetics, environment and culture
• Some skip and remain normal.
• As more skills are mastered and developed.