Chapter 1: Fundamental concepts of motor development
In Life Span Motor Development, Haywood and Getchell (2019) introduce the concept of
constraints in motor development, emphasizing how various factors shape movement. “Karl
Newell (1986) suggested that movements arise from the interactions of the organism, the
environment in which the movement occurs, and the task to be undertaken” (Haywood &
Getchell, 2019, p. 6). This is what we call Newell’s model of constraints. To begin discussing the
progression of human motor movement abilities over the lifespan, we look at Newell’s model.
Looking at infancy and early childhood, each of the constraints plays an important role in the
child's motor development. For example, when a child is no longer being held in the mother's
arm and has transitioned to more ground time, we get an environmental change. Now that the
child is on the ground more often and getting stronger day-by-day, they begin to take advantage
of their abilities (individual constraints) and are no longer staying on their hands and knees but
begin to get their feet under them to stand. Now that the child has improved their ability to walk
with early walking characteristics, they begin to expand their boundaries to outside conditions,
resulting in them walking on grass more often, causing them to be unbalanced and having to put
more focus toward coordination, leading them to become more proficient walkers (Task
constraint).
Newell’s model of constraints explains how motor development is shaped by the
interaction of individual, environmental, and task constraints throughout life (in this case,
infancy). During infancy and early childhood, these constraints play an important role in both the
progression and variability of motor skills. As a child transitions from being held to spending
more time on the ground (environmental constraint), it provides new opportunities for
movement. As their strength and coordination improve (individual constraints), they begin to
progress from crawling to standing and eventually walking. However, variability in development
is evident as each child adapts differently based on their unique constraints. While all children
follow a universal sequence of motor development, factors such as strength, balance, and
exposure to different surfaces (task constraints) influence the pace and quality of their movement
skills. This interaction highlights how universality ensures a general pattern of motor milestones
while variability allows for individual differences in how and when these milestones are
achieved.
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Chapter 2: Theoretical Perspectives in Motor Development
Motor development has been studied through various theoretical lenses, with the
maturational perspective and the ecological approach being two of the most influential. The
maturational perspective emphasizes biological and genetic factors as the primary drivers of
development, whereas the ecological approach, particularly through the dynamical systems and
perception-action models, highlights the role of environmental interactions in shaping
movement. “Gesell believed that the biological and evolutionary history of humans determined
their orderly and invariable sequence of development” (Haywood & Getchell, 2019, p. 18).
The maturational perspective suggests that progression in motor development occurs as
the central nervous system matures. This means that motor skills follow a universal sequence;
because development is largely biologically driven, progression is seen as a natural unfolding of
motor skills over time. However, this view does not fully explain individual variability in motor
learning or adaptation to different environments. Over time, motor abilities regress due to agerelated biological changes and external constraints. The maturational perspective attributes
regression mainly to biological decline, such as muscle weakness, slower neural processing, and
reduced flexibility, which naturally occur with aging. This decline leads to reduced coordination
and balance, affecting activities such as walking, running, or fine motor skills.
The ecological approach, on the other hand, specifically the dynamical systems theory,
explains progression as an interaction of multiple factors, including individual constraints,
environmental conditions, and task demands. Unlike the maturational perspective, which sees
development as a fixed sequence, the perception-action approach highlights how children learn
movements by perceiving opportunities (affordances) in their environment. For example, as a
child learns to walk, they adjust their movements based on surface texture, obstacles, or support
from parents. This approach, however, provides a broader explanation, suggesting that regression
occurs due to changes in the interaction between the individual, environment, and task
constraints. For example, an older adult may experience individual constraints, but regression
may also be influenced by environmental constraints and task constraints. The perception-action
approach explains how older adults adjust their movements based on sensory decline, such as
modifying their walking patterns to accommodate reduced depth perception.
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Chapter 3: Principles of Motion and Stability
In motor development, stability and balance are essential components of movement
control and skill acquisition throughout the lifespan. Stability refers to the body's ability to
maintain equilibrium, while balance involves controlling the body's center of mass in relation to
its base of support (Haywood & Getchell, 2019, p. 38). As individuals progress through different
stages of motor development, their ability to maintain stability in both static and dynamic
conditions improve. For example, young children learning to walk often adopt a wide stance and
take short steps to enhance balance, whereas older adults, facing declines in strength and
coordination, adjust posture and foot placement to reduce the risk of falling. This shift highlights
the stability-mobility trade-off, which describes how increased stability often comes at the cost
of reduced mobility. In early development, children prioritize stability over mobility to establish
fundamental movement patterns such as standing and walking. However, as they gain confidence
and strength, they begin to emphasize mobility over stability, enabling them to develop more
efficient and dynamic movement skills such as running and jumping. In later adulthood, this
process often reverses, as individuals experience a natural decline in muscle strength, reaction
time, and balance control. To compensate, they rely more on stability-based strategies, such as
widening their stance, walking at a slower pace, or using assistive devices, demonstrating how
motor development is a continuous and adaptive process shaped by changes in individual,
environmental, and task constraints throughout life.
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Chapter 4: Early Motor Development
In Life Span Motor Development, Haywood and Getchell (2019) describe the appearance
and disappearance of reflexes as critical indicators of neurological maturity, guiding the
transition from involuntary movements to voluntary motor control. Reflexes, which
are automatic responses to specific stimuli, emerge at birth or shortly after and play an essential
role in early movement patterns. Examples such as the Moro reflex, rooting reflex, and stepping
reflex contribute to both survival and the development of foundational motor skills. However, as
the central nervous system matures, many primitive reflexes begin to disappear, allowing for
more controlled and voluntary movement patterns to take shape. For instance, the stepping
reflex, which causes infants to make stepping-like motions when held upright, naturally fades
after a few months but later re-emerges as part of independent walking development. This
transition highlights how reflexes serve as precursors to more complex motor abilities, preparing
the body for coordinated movement, strength development, and postural control.
As reflexes fade, they are replaced by motor milestones, which serve as key indicators of
voluntary movement progression. These milestones, such as lifting the head, rolling over, sitting
independently, crawling, and walking, follow a universal developmental sequence, but the timing
varies due to individual constraints (Haywood & Getchell, 2019). This shift from reflexive to
voluntary control reflects the gradual acquisition of strength, coordination, and neuromuscular
development, enabling purposeful actions. For example, an infant must first develop postural
control by lifting their head and sitting before progressing to more complex locomotor skills such
as crawling and walking. Although most infants achieve these milestones in the same order,
the rate of progression differs, influenced by factors such as muscle strength, sensory feedback,
and movement opportunities. This variation reinforces the interplay between universality and
variability in motor development, where all humans follow a general developmental pathway but
adapt differently based on individual, environmental, and task constraints.
Motor skills continue to refine through childhood, adolescence, and adulthood,
enhancing efficiency, coordination, and voluntary movement precision. However, as
individuals age, motor regression occurs due to declining muscle strength, slower neural
processing, and decreased sensory feedback. In healthy adults, reflexes remain largely
suppressed, but some primitive reflexes may resurface in later adulthood due to neurological
deterioration, particularly in individuals with conditions such as Parkinson’s disease or dementia.
Likewise, early motor milestones, such as balance, coordination, and locomotor abilities, may
gradually decline with age. For example, older adults often experience reduced postural stability
and walking difficulties stemming from weakened muscles, joint stiffness, and impaired sensory
processing. As a result, they may adopt more stable movement patterns, such as shorter strides,
wider stances, and slower walking speeds, mirroring the early stages of locomotor
development seen in infancy. This lifelong cycle of progression and regression highlights
the dynamic nature of motor development, continuously shaped by the interactions between
individual, environmental, and task constraints across the lifespan.
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Chapter 5: Development of Human Locomotion
In Life Span Motor Development, Haywood and Getchell (2019) describe the evolution of
walking and running across the human lifespan, emphasizing the interplay of individual,
environmental, and task constraints. The progression and regression of these motor abilities are
dynamic, shaped by a variety of factors throughout life.
Walking is one of the first major milestones in a child's motor development. Beginning
with early crawling, children gradually gain the strength and coordination necessary to stand and
eventually take their first steps. As children develop, environmental factors, like the surface they
walk on, influence the quality of their walking. For instance, children may struggle to walk on
uneven surfaces, such as grass, as they focus on maintaining balance, but with practice, they
adapt and improve their coordination. As they progress, children typically exhibit a fifty percent
phasing between the legs, where one leg swings forward as the other pushes off the ground,
allowing for a more fluid and coordinated gait. As individuals age, walking abilities can regress
due to changes in strength, balance, and flexibility. Older adults, for example, may experience a
reduction in walking speed or stability, which can lead to a higher risk of falls, reflecting a
decline in motor abilities due to aging.
Running, another key motor skill, also shows a clear progression. In childhood, as
children grow stronger and more coordinated, they transition from walking to running, typically
exhibiting early running patterns such as short strides and limited arm swing. Over time, with
practice and environmental exploration, running becomes more efficient and refined, and adults
can run with greater speed and fluidity. However, as people enter middle and late adulthood,
running abilities often decline, with older adults experiencing slower speeds and diminished
endurance. This regression is influenced by both physiological changes, such as muscle atrophy
and joint stiffness, and environmental factors like decreased opportunities for physical activity.
The progression and regression of walking and running highlight the importance of Newell's
model of constraints in motor development. Throughout the lifespan, individual, environmental,
and task constraints interact to shape movement abilities, demonstrating the balance between
universal milestones and individual variability. Whether it's a child taking their first steps or an
elderly person navigating a park, these movements are influenced by a dynamic blend of internal
and external factors.
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Chapter 6: Development of Ballistic Skills
Ballistic skills, such as throwing, are fundamental movements that undergo
significant development and potential regression throughout a person's life. In Life Span Motor
Development, Haywood and Getchell (2019) investigate these changes, with a particular focus on
overarm throwing and throwing for accuracy. These skills, seemingly simple, are complex motor
patterns influenced by individual, environmental, and task constraints.
Throwing for accuracy involves a nuanced interplay of motor control and coordination.
It's not simply about generating force but about directing that force with precision. Consider a
child learning to throw a ball at a target. Initially, their movements might be uncoordinated,
involving the whole body in a rather chaotic manner. However, with practice and feedback, they
begin to refine their technique, learning to dissociate trunk rotation from arm movement and to
time the release of the ball more effectively. This progression is not always linear. As Haywood
and Getchell would likely point out, throwers might even revert to earlier developmental stages
when prioritizing accuracy over force. We see this every day, like when someone lobs a beanbag
in cornhole.
Overarm throwing, a cornerstone of many sports and recreational activities, exhibits a
clear developmental sequence. Early overarm throwing is characterized by restricted arm action,
with the movement primarily occurring at the elbow. As individuals mature, they incorporate
more of their body into the throw, utilizing trunk rotation, weight transfer, and a coordinated arm
swing to generate greater force and velocity. The observation of children playing catch vividly
illustrates this progression. The younger ones rely heavily on their arms, while older children and
adolescents display a more fluid and integrated movement pattern. It's interesting that most
fundamental motor skills, like overarm throwing movements, are naturally acquired as children
play and move around by themselves.
It’s important to acknowledge that the development of throwing skills isn’t solely about
progression. Regression can occur due to factors such as injury, decreased physical activity, or
age-related decline. An athlete recovering from a shoulder injury, for instance, might need to
relearn proper throwing mechanics, potentially displaying less advanced movement patterns
during the rehabilitation process. Similarly, older adults might experience a decline in throwing
velocity and accuracy due to reduced muscle strength and coordination.
In essence, the lifespan development of throwing skills, whether for accuracy or power,
mirrors the broader principles of motor development. It's a dynamic process shaped by the
continuous interaction of individual capabilities, environmental conditions, and the specific
demands of the task.
References
Haywood, K. M., Haywood, K., & Getchell, N. (2019). Life Span Motor Development. Human Kinetics.
OpenAI. (2025). ChatGPT (March 6 version) [Large language model]. https://openai.com
Fleisig, G. S. (1999). Phases of the overhand throw. Journal of Biomechanics, 32(12), 1371-1375.
https://doi.org/10.1016/S0021-9290(99)00104-8