Reconceptualizing and Operationalizing Seefeldt's Proficiency Barrier: Applications and Future Directions

Abstract

In 1980, Seefeldt introduced the concept of a motor skill "proficiency barrier" that provides a conceptual basis for understanding the importance of a motor skill barrier as it relates to critical public health initiatives. While the intent of Seefeldt's proficiency barrier hypothesis had great potential to advance the field of motor development, the notion of a proficiency barrier was not empirically tested. Instead, this concept lay dormant for several decades. The purpose of this paper was to expand upon Seefeldt's proficiency barrier concept in greater detail by addressing the following questions: (1) what constitutes a motor proficiency barrier? (2) how do we assess/measure the existence of a proficiency barrier? and (3) how do we break through the proficiency barrier in order to maximize the likelihood of participation in health-enhancing levels of physical activity later on in life? We conclude with a future research suggestion to explore the existence of the proficiency barrier.

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Vol.:(0123456789)
Sports Medicine
https://doi.org/10.1007/s40279-020-01332-6
REVIEW ARTICLE
Reconceptualizing andOperationalizing Seefeldt’s Prociency Barrier:
Applications andFuture Directions
AliBrian1 · NancyGetchell2 · LarissaTrue3 · AnDeMeester1 · DavidF.Stodden1
© Springer Nature Switzerland AG 2020
Abstract
In 1980, Seefeldt introduced the concept of a motor skill “proficiency barrier” that provides a conceptual basis for under-
standing the importance of a motor skill barrier as it relates to critical public health initiatives. While the intent of Seefeldt’s
proficiency barrier hypothesis had great potential to advance the field of motor development, the notion of a proficiency
barrier was not empirically tested. Instead, this concept lay dormant for several decades. The purpose of this paper was to
expand upon Seefeldt’s proficiency barrier concept in greater detail by addressing the following questions: (1) what constitutes
a motor proficiency barrier? (2) how do we assess/measure the existence of a proficiency barrier? and (3) how do we break
through the proficiency barrier in order to maximize the likelihood of participation in health-enhancing levels of physical
activity later on in life? We conclude with a future research suggestion to explore the existence of the proficiency barrier.
Key Points
A proficiency barrier may impede the developmental
transition between stability and mobility.
Most children will develop a minimal level of compe-
tency with motor skills (e.g., stability patterns) with
free play and little instruction. To break through the
proficiency barrier, children need structured movement
experiences early to learn mobility patterns. We suggest
mobility patterns are culturally promoted whereas stabil-
ity patterns are more species-typical.
We challenge the readership to explore empirically test-
ing the existence of the proficiency barrier.
1 Introduction
Over the past 30years, an alarming upward trend in obesity
rates has occurred, almost tripling since 1975 [1]. During the
same period, daily physical activity rates have dropped sub-
stantially and sedentary behavior has increased [2]. Equally
alarming, but far less recognized, is a secular decline in
motor competence levels in young children over the past sev-
eral decades. For example, Brian and colleagues [3] reported
Ali Brian and Nancy Getchell are co-lead authors with equal
contributions
* Ali Brian
brianali@mailbox.sc.edu
1 Department ofPhysical Education, University ofSouth
Carolina, 1300 Wheat St., Columbia, SC, USA
2 Department ofKinesiology andApplied Physiology,
University ofDelaware, Newark, DE, USA
3 Department ofKinesiology andDance, New Mexico State
University, LasCruces, NM, USA

A.Brian et al.
that 77% of a sample of children ages 3–5years from across
the US were at or below the 25%tile with approximately 30%
of children demonstrating profound developmental delays
(< 5%tile) in their gross motor skills. However, policymak-
ers and practitioners have been slow to make the connection
between physical activity and motor competence. We argue,
the failure to make this link occurs by addressing the need
to increase physical activity in isolation from the context of
activity from a holistic, developmental perspective (i.e., how
well they move) [4, 5].
In essence, only focusing on promoting a greater “amount
of time” in moderate-to-vigorous physical activity (MVPA)
without regard to how individuals move when they are active
and why they are motivated to sustain PA behaviors is prob-
lematic when considering that child development is a com-
plex and dynamic process [5–8]. Recent longitudinal and
other meta-analysis data speak to the potential long-term
impact that developing motor competence has on PA [9, 10],
multiple aspects of health-related fitness [11–13], weight
status [12, 14, 15], and other critical aspects of child devel-
opment [7, 16, 17]. Thus, failure to acquire ‘adequate’ levels
of competence in a broad variety of motor skills in childhood
could partially explain and parallel the secular decline in
physical activity and fitness, and the rise in obesity levels
across childhood, adolescence, and into adulthood. Unfor-
tunately, the term “adequate” currently has not been empir-
ically defined. However, in 1980, Seefeldt introduced the
concept of a motor skill “proficiency barrier” that provides
a conceptual basis for understanding the importance of suf-
ficient motor competence levels as an integral part of physi-
cal activity as it relates to critical public health initiatives.
1.1 History andPotential Importance
ofaProciency Barrier?
Seefeldt [18] proposed that motor development occurred via
progression through developmental periods that were repre-
sented in a conceptual model (see Fig.1). Level 1 consists of
reflexes (e.g., palmar grasp, Babinski, startle) and postural
reactions generally situated in infancy (e.g., rolling, sitting
up, pulling up to stand) and is followed by a period framed
within early childhood (i.e., 2–5years old) that is linked
to the acquisition of ‘fundamental motor skills’ (e.g., run-
ning, jumping, throwing, catching), which are precursors
to activities that require more skill-specific adaptations for
games and sports (e.g., baseball, soccer, tennis). Seefeldt
placed a proficiency barrier between the fundamental motor
skill development period in early childhood and transitional
skills during middle childhood into adulthood. Transitional
skills assist with the transition from basic patterns to con-
text-specific use of skills in games and activities such as
lead up activities (throw-and-catch volleyball), small-sided
games [small dimensions, slower speeds, fewer players], and
non-sport specific skills (e.g., jump rope). Seefeldt noted,
“The proficiency barrier is placed between the ‘fundamen-
tal’ and ‘transitional’ skills because our work has shown that
children who are deprived of learning the fundamental skills
have difficulty when they attempt to learn the transitional
motor skills (pp. 316)” (italics added). In 1986, Hauben-
stricker and Seefeldt suggested the proficiency barrier may
also have implications later in childhood with respect to par-
ticipation in activities that require vigorous physical effort
as successful and sustained participation would demand
competency in various motor skills inherently integrated in
a broad spectrum of activities (e.g., games and sports) [19].
While the intent of Seefeldt’s proficiency barrier hypothesis
had great potential to advance the field of motor develop-
ment, the notion of a proficiency barrier was not empirically
tested. Instead, this concept lay dormant for several decades.
Thus, one focus of this paper will be to operationalize (i.e.,
to put something to use or into operation) the proficiency
barrier, specifically focusing on its potential importance in
the public health domain and as it relates to other aspects of
child development.
Malina [20] recently revisited Seefeldt’s concept using
the proficiency barrier as one of the top ten questions that
researchers should address to combat the continued trend
in childhood obesity. Malina suggested that there may
be a level of movement competence above which a child
would be more likely to engage in various physical activi-
ties, including sport, and below which a child would be
less likely to engage in such activities,” (pp 164). Malina
followed with, “Is there a critical level of movement pro-
ficiency (competence) that facilitates physical activity and
sport participation (in children and adolescents)?” (pp 164).
Fig. 1 Seefeldt’s original conception of the proficiency barrier.
Adapted with permission from Seefeldt V. Developmental motor pat-
terns: implications for elementary school physical education. Psy-
chology of motor behavior and sport—1979 [18]

Operationalizing Seefeldt’s Proficiency Barrier
Two recent studies have explored the proficiency bar-
rier concept relating motor competence levels to aspects
of health. Stodden etal. [21] tested for a proficiency
barrier using a product-oriented composite skill battery
including throwing and kicking speeds and jumping dis-
tance to predict normative levels (i.e., good, fair, or poor)
of health-related fitness levels in young adults. Only 2.5%
(2 out of 65) 18- to 25-year-old adults who were classified
as “low-skilled” (i.e., the lowest 35%tile of the sample)
were classified as having “good” health-related fitness
(≥ 60%tile based on normative fitness data). 97.5% of
participants classified as high-skilled (> 60%tile) dem-
onstrated at least “fair” (i.e., ≥ 36%tile) fitness. While the
findings did not definitively identify a proficiency bar-
rier, the very low percentage of individuals in the lowest
third of motor competence that demonstrated fair fitness
levels (2.5%) is consistent with predicted outcomes of a
proficiency barrier.
Similar results were found in a more recent study
where researchers tested a specific barrier of “at risk for
developmental delay” (< 25%tile based on a normative
assessment of twelve motor skills) and examined its capa-
bility to predict the likelihood that children in middle and
late childhood (7–12years old) would participate in at
least 60min of moderate-to-vigorous physical activity
per day [22]. Children with more advanced skill levels
(i.e., > 65%tile of motor competence) were 2.5 times more
likely to meet the MVPA guideline than lower skilled
children (i.e., < 65%tile). Specific to the proficiency bar-
rier concept, < 12% (29 out of 248) of children at or below
the 25% tile met the MVPA guidelines.
Data from these two studies, although limited in their
capability to definitively identify a proficiency barrier,
offer compelling insight and a novel strategy to inves-
tigate the impact of motor skill development on various
health-related variables across childhood. Additional
research is needed to systematically examine attributes
of skill development that not only can be linked to further
skill advancement and a potential proficiency barrier, but
also may be linked to other critical child development
variables (e.g., self-concept, weight status). The purpose
of this paper was to expand upon Seefeldt’s proficiency
barrier concept by reconceptualizing the notion of a
proficiency barrier and attempting to operationalize it
with a focus on the public health and child development
domains. Specifically, we address the following ques-
tions: (1) what constitutes a motor proficiency barrier?
(2) how do we assess/measure the existence of a profi-
ciency barrier?; and (3) how do we break through the
proficiency barrier in order to maximize the likelihood of
participation in health-enhancing levels of physical activ-
ity later on in life?
2 Question 1: What Constitutes aProciency
Barrier?
One demarcation point that may define a proficiency bar-
rier, or a dichotomous separation in motor competency
levels, may exist at the point at which children transi-
tion their movement emphasis from movement stability
(i.e., prioritizing the maintenance of a stable, upright
posture) to mobility (i.e., maximizing movement capa-
bility and performance) in a variety of intra-task devel-
opmental sequences [23]. That is, a proficiency barrier
may exist at a point of transition along a developmental
trajectory between movement pattern coordination strat-
egies designed to facilitate an underlying goal of either
stability or mobility. Promoting increased mobility (vs.
stability) inherently involves many critical underlying
aspects of learning and development including percep-
tuomotor integration, motivation, practice, intrinsic and
augmented feedback, self-perceptions, as well as a myriad
of potential goals (e.g., environment exploration for an
infant, increased speed of movement, increased center
of mass [COM] translation capability to transfer energy
through the kinetic link system for object projection tasks).
If a proficiency barrier exists, children will not progress
within a number of different specific skill developmental
sequences (i.e., demonstrate higher developmental levels
in different action components over time that promote
mobility). In other words, children continue to demon-
strate lower developmental levels in multiple skills over a
long period of time.
However, while our suggestion that mobility vs. sta-
bility may be one critical differentiation point in skill
development, it is not our intent to minimize the inherent
complexities involved in the development of motor coor-
dination and control, nor is it our intent to provide a one-
size fits all approach to operationalize a dichotomous skill
competence barrier. We have chosen to use the locomotor
skill of walking as an exemplar to illustrate the stabil-
ity vs. mobility idea, as it is the first independent bipedal
locomotor skill acquired throughout the lifespan, while
also noting that many different locomotor skills (e.g., run-
ning, hopping, skipping, etc.) demonstrate similar devel-
opmental progressions in stability to mobility coordination
strategies. From a holistic perspective, the development
to more advanced levels of walking promotes increased
physical activity via the expansion of children’s capabili-
ties for exploration of their physical environment. For a
new walker, controlling postural stability in order to main-
tain balance is the most difficult challenge to overcome in
order to move independently on two feet. Walking requires
the ability to continuously move the center of mass for-
ward over an alternating base of support (i.e., alternating

A.Brian et al.
balance on one foot). If movers cannot maintain an upright
posture while repetitively shifting the COM forward (i.e.,
cyclical dynamic balance) over their base of support while
responding to reactive forces generated by their own move-
ments and changing environmental conditions, they will
not effectively and efficiently maximize forward move-
ment. A “stability” strategy of limb configurations maxi-
mizes overall body stability (e.g., shorter stride, wider
base of support, arms in a high guard position and lower
center of gravity), which in turn minimizes the odds of
falling while limiting walking speed [24–26]. A stability
strategy reflects the goal of maximizing a stable, upright
posture at the expense of walking speed. Many locomotor
skills in their earliest forms, such as hopping and gallop-
ing, share similar upper and lower body configurations that
optimize stability. The transition to a more advanced and
efficient mobility strategy, facilitated by practice, maxi-
mizes COM forward movement and minimizes horizon-
tal COM translation with longer strides and oppositional
coordination with the upper extremities. Similar advance-
ments in coordination strategies for other locomotor skills
are required to be successful in many activities that require
advanced mobility patterns and represent Seefeldt’s notion
of advancement across the proficiency barrier to more
transitionary skills.
2.1 Are Skills Species‑Typical orCulturally
Promoted?: APreliminary Discussion
Historically, it was assumed that the process of motor skill
acquisition in infancy and childhood occurred automatically
through maturation of the central nervous system [27–29].
According to this maturational perspective, early motor
skills emerged over time in a species-specific, orderly pro-
gression with limited impact from the environment during
infancy and childhood. McGraw’s 1935 longitudinal study
on Johnny and Jimmy examined the role of heredity and
environment on motor behavior, which challenged the matu-
rational perspective [30]. McGraw distinguished between
species-typical (i.e., phylogenetic) motor skills, those nat-
urally occurring skills essential for basic functioning and
survival, and culturally promoted (i.e., ontogenetic) skills,
whose development was based on individual experiences.
This early motor development research shed light on the
importance of experience in motor skill acquisition. Further,
it arguably set the stage for a shift away from a maturational
perspective, and also indirectly provides the rationale for a
proficiency barrier framework. Children will often be able
to perform many motor skills in a rudimentary form (i.e.,
fundamental) without practice or instruction, using body
configurations that increase body stability. However, cul-
turally promoted skills, often used in sport contexts, require
individuals to generate force (run faster, jump higher, kick
or throw a ball farther or faster). In essence, the notion that
instruction and practice under different environmental condi-
tions is necessary to advance from stability to mobility strat-
egies speaks to the idea of species-typical versus culturally
promoted skill development.
2.2 Stability Strategies may be More
Species‑Typical orInnate; Mobility Strategies,
More Culturally Promoted, orLearned
The suggestion that the adoption of stability strategies may
be more species-typical (innate to and more consistent
across humans) than culturally promoted (learned through
experiences and more varied across humans) supports the
idea that most children develop stability strategies without
much external instructional support (e.g., [31]; see Sect.4.2
for more detail). Following the logic of Bernstein [32], early
learners often constrain or ‘freeze’ joint movement to limit
the number of moving segments (degrees of freedom) to
accomplish a movement goal. This freezing of limb move-
ments can be observed in early forms of many motor skills as
a means of simplifying movement control, but limits the sys-
tem’s capability and flexibility to respond to perturbations
that challenge stability and balance [33]. Continuing from
our previous example, early walkers constrain degrees of
freedom by taking short steps that minimize lower extremity
joint ranges of motion and trunk rotation, which maximizes
the period of double foot support. Furthermore, a “high
guard” position (e.g., holding arms out at shoulder level)
of the upper extremities is maintained in order to minimize
lateral excursions of the COM, concurrently decreasing the
need for large reactive forces created during forward move-
ment with each step [25, 34, 35]. The initial coordinative
pattern results in a variable COM translation path in both
the anterior–posterior and medial–lateral directions. Using
a stability strategy for locomotion contributes to the capa-
bility to maintain an upright posture while moving, but also
drastically limits the overall velocity (i.e., both speed and
directional goals) of locomotion. When addressing the pro-
gression of different locomotor patterns across childhood,
the transition from a quadri- (i.e., crawling) to bi-pedal pat-
tern (walking), and then from walking to running represent
potential different transition “barriers” that may be linked to
physical activity levels and other child development factors.
Similar stability strategies that constrain degrees of free-
dom also can be identified within foundational forms of sev-
eral locomotor skills, such as running [36, 37], hopping [38,
39], and jumping [40, 41] (Figs.2, 3, 4). Specifically, the
use of the high guard arm position is again utilized in less
advanced patterns of both hopping and running to maintain
postural stability at the expense of performance (i.e., trans-
lation of the body in the anterior direction). Even when the
high guard arm position (i.e., increased shoulder abduction)

Operationalizing Seefeldt’s Proficiency Barrier
is no longer used in walking, this strategy is employed when
individuals push the transitionary skill boundary towards
greater mobility in more complex skills (e.g., running) [42,
43]. High guard also is employed in less advanced hopping,
in which only the stance leg action promotes forward move-
ment of the COM at the earliest developmental levels [44].
Fig. 2 Developmental sequences for running. Adapted with permission from Haywood and Getchell [50]
Fig. 3 Total body developmental sequences for Jumping Adapted with permission from Haywood and Getchell [50]. Also adapted with permis-
sion from Clark and Phillips [40]
Fig. 4 Hopping developmental sequences Adapted with permission from Roberton and Halverson [80]. Also adapted with permission from Rob-
erton and Halverson [44]

A.Brian et al.
These coordination patterns optimize stability in that they
are reactionary and reflexive movements that serve to main-
tain upright posture. As they appear to be ubiquitous across
locomotor skills in early childhood, we suggest they are
species-typical in that overt instruction is not demanded for
the demonstration of these rudimentary movement patterns.
Advancing from more rudimentary coordination patterns
to those that maximize mobility requires the shift from pri-
marily reactionary and stability-based movements to inten-
tional performance-enhancing movements. Transitioning to
culturally promoted movement patterns requires that individ-
uals explore the boundaries of their stability strategies and
may initially promote a high degree of variability in move-
ment patterns and performance. This exploration occurs by
voluntarily testing movement capabilities via increasing
effort and force production in upper and lower extremity
movements that serve to project the body. Increased force
production may increase the angular velocity and range of
motion across multiple joints, leading to changes in the
speed and/or directionality of the overall movement. These
initial attempts to increase effort and the overall resultant
speed of movement may occur in lower and/or upper extrem-
ity and can promote a general destabilization of the existing
rudimentary coordination patterns. This destabilization leads
to highly variable limb movements and potentially decreased
stability (i.e., loss of balance).
Decreased stability, in the transition to a more highly
advanced coordination pattern, is a necessary function of
development noted by an increase in the overall output of
the system (e.g., movement speed) and may result in the
individual falling or completely stopping the movement pat-
tern temporarily so as not to fall. A risk vs. reward poten-
tial in destabilizing movement is necessary to advance to a
different coordination pattern and next level of movement
performance. For example, when hoppers shift away from
stability coordination patterns, increases in force produc-
tion serve as a catalyst to “release” constrained limbs and
reorganize the system into a new coordination pattern (e.g.,
arms pump in opposition or semi-opposition to each other
vs. a high guard position). Somewhat similar in the devel-
opment of hopping is a coordination pattern between the
non-support leg and arm movements that demonstrate an
opposing anterior–posterior coordination pattern with the
non-support leg and the contralateral upper extremity. The
emergence of a new coordination pattern is generally associ-
ated with an increased speed of COM translation (i.e., body
projection) and produces a system that is able to hop faster
and/or higher with a greater flight phase or hopping distance
[45]. In a less advanced coordination pattern the non-support
leg is suspended in front of the body (i.e., relatively fixed
hip flexion and knee flexion) while the arms demonstrate
a variable coordination pattern (e.g., high guard or bilat-
eral winging movements). These less advanced movements
do not promote any additional projection capabilities in the
anterior/posterior plane and thus, the stance leg is the only
aspect of movement promoting forward movement of the
system. Both of these less advanced movements demonstrate
a lack of rhythmical opposing contralateral coordination pat-
terns (i.e., anterior and posterior directions) that would pro-
mote mobility. As the phenomenon of stability to mobility
coordination strategies is demonstrated across all bipedal
locomotor skills, we propose it as a testable proficiency bar-
rier in this broad category of skill development.
Interestingly, some of these same stability/mobility tran-
sitional movement features also are present in some levels in
object control skills that demonstrate increased COM trans-
lation across advancing developmental levels. For example,
in throwing, increased COM translation speed parallels
increases in step, trunk, humerus, and forearm development
levels [46, 47], as well as increases in ball speed. When
contrasting the most rudimentary coordination pattern of
throwing to the most advanced pattern, a clear distinction
can be made with respect to the transition from a bilateral
dominated stability stance and limited upper extremity
movements (i.e., no step, limited trunk rotation and lim-
ited movements) to a unilateral stance and where the COM
reaches anterior translation speeds of greater than 2m/s [46].
In addition, highly advanced throwing also demonstrates
bilateral opposition in the upper extremities that is associ-
ated with high velocity trunk and arm segmental speeds as
the entire body mass is projected forward while simultane-
ously rotating upon a fixed unilateral stance position. Thus,
the transition from a stability posture (i.e., bilateral stance
with limited trunk and upper extremity speed and range of
motion movements) to a highly dynamic unilateral stance
with upper extremity bilateral opposition mirrors the transi-
tion from stability to mobility movement strategies demon-
strated in locomotor skills. The same general developmental
continuum also is seen in the skill of kicking [48].
2.3 The Stability–Mobility Trade O: What
Facilitates Motor Skill Acquisition andTransition
fromRudimentary, Stability Strategies toMore
Advanced Mobility Strategies?
The development of complex coordination patterns across
time does not occur in a linear and straightforward manner as
noted in the above-mentioned classifications of stability vs.
mobility movement descriptions. In order to advance move-
ment patterns across the barrier from stability-promoting,
species-typical patterns to more culturally promoted pat-
terns that support enhanced mobility, multiple environmen-
tal stimuli are required [49]. The emergence of more highly
advanced coordination patterns evolves across many hours
and potentially years of practice and diverse learning expe-
riences that are facilitated by various forms of instruction

Operationalizing Seefeldt’s Proficiency Barrier
(e.g., teaching and modeling) and feedback (e.g., intrinsic
and augmented). However, the relative simplicity of the
aforementioned anatomical and biomechanical stability vs.
mobility explanations aligns with the dichotomous explana-
tion of an overall movement system “barrier” that must be
overcome in order to advance to higher levels of coordi-
nation and performance that will serve to promote lifelong
participation in the plethora of activities that involve these
skills.
3 Question 2: How Do We Assess/Measure
theExistence ofaProciency Barrier?
One potential strategy to measure the stability versus mobil-
ity profile would be to use the component developmental
sequences approach [50] (Table1, Figs.2, 3, 4). The sug-
gested use of developmental sequences, which outline
ordinal levels of movement for specific body components,
can delineate a specific skill barrier (i.e., a barrier being
a measurable dichotomous distinction) from a qualitative
perspective (e.g., the transition from a level 1 to a level 2
may be a measurable mobility/stability transition point) and
speaks to a dynamical systems framework with distinct order
parameter differentiation [51]. Further, it can help identify
a general proficiency barrier when children demonstrate
lower developmental levels in a wide variety of skills. Other
process-oriented assessments may also be useful in this man-
ner as there are specific critical elements that may speak to
a specific transition point as well. Specifically, the Test of
Gross Motor Development (TGMD) or others like it (e.g.,
Get Skilled Get Active [52]) assessments have “present or
absent” critical elements. Measuring skill levels with assess-
ments that demonstrate specific qualitative coordination
pattern differences (see Table1, Figs.2, 3, 4) can then pro-
mote the creation of stability versus mobility profiles to test
against the likelihood of achieving health-enhancing levels
of physical activity, fitness, weight status, and participation
in sports and games.
Product-oriented assessments would inherently have
greater difficulty differentiating a mobility/stability bar-
rier as they provide continuous/scaled data. However, this
process could entail comparing product scores against a
process-oriented assessment for comparison or predic-
tion [54]. Process- and product-oriented assessments that
have normative levels also provide another means to note
a potential proficiency barrier in their classification of risk
for developmental delay (e.g., < 15th or < 25th percentiles)
that may not be linked to specific skill movement patterns,
yet provide comprehensive skill level classifications. This
process would be more difficult in the sense that these lev-
els are variable depending on how percentiles are used for
classification purposes (e.g., different states use different “at
risk” levels or cultural differences). Thus, our initial thought
of using developmental sequences provides a means to non-
arbitrarily test for a potential barrier in both general and spe-
cific skills as well as within established test batteries that can
be linked, not only to critical public health outcomes, but
also to other product-oriented skill classifications that would
align with this dichotomous divide in qualitative coordina-
tion patterns. We have provided a table to provide examples
of how stability and mobility profiles may be assessed (see
Table1, Figs.2, 3, 4). Coincidentally, both papers that have
initially addressed the possibility of a barrier [21, 22] have
used process (i.e., TGMD normative levels associated with
“at risk” for developmental delay) as well as product scores
(throw/kick speed and jump distance) to “test the waters”
of the proficiency barrier as they relate to health-related
outcomes.
4 Question 3: How Do We Break
Through theProciency Barrier
inOrder toMaximize theLikelihood
ofParticipation inHealth‑Enhancing
Levels ofPhysical Activity Later oninLife?
4.1 Shifting fromStability toMobility Does
Not Occur ‘Naturally’ butRequires Practice
andExperience
Motor development research during early childhood casts
light on the importance of experience in acquiring more
advanced motor skills and sets the stage to shift away from
a maturational perspective towards an approach that better
supports the role of learning in skill development (i.e., cul-
turally promoted experience). Newell’s constraints model
Table 1 Suggested profiles for stability and mobility
See Figs. 2, 3 and 4 for a description of each movement. For a
description of the Test of Gross Motor Development-3 (TGMD-3)
items, please refer to the TGMD-3 manual [53]
Action Developmental
sequences
TGMD-3
Stability Mobility Stability Mobility
Run 0–7 8
Leg 1 or 2 3
Arms 1, 2, or 3 4
Jump
Total body 1, 2 3, 4 0–5 6–8 arms do not
have to fully
extend
Hop 0–7 8
Leg 1, 2, 3, 4
Arm 1, 2, 3, 4 5

A.Brian et al.
[55] provides conceptual framework whereby motor skill
development results from repetitive and progressive practice
in various environments over time; these experiences inter-
act along a growth and maturation continuum resulting in
advancing movement patterns. Although the role of growth
and maturation in motor skill development plays a specific
role in skill development across childhood and adolescence,
the age-related, but not age-dependent, notion of develop-
ment [56] specifically embodies the impact of experience
(i.e., ontogeny) to move beyond the proficiency barrier. Con-
sider the argument by Langendorfer and Roberton [31] that
rudimentary levels of the developmental sequence for throw-
ing may be species-typical, in that most individuals could
reach this level of throwing with relatively minimal practice.
They reasoned that most individuals required a considerable
amount of practice to reach the most advanced developmen-
tal levels of over arm throwing, thus making advanced skill
development culturally promoted. Cast in a more general
way, the acquisition of some fundamental motor skills such
as walking and throwing require minimal practice to demon-
strate rudimentary forms of the motor skill (e.g., adopting a
stability coordination strategy). These skills can be consid-
ered species-typical in that they exist independent of country
or culture [57]. Soon after acquiring these rudimentary, sta-
bility phase movement patterns, specific experiences guide
further improvement in skill (e.g., shifting from stability to
mobility strategies) and demonstration of advanced levels
requires significant amounts of practice based on the context
in which the skill will be used [54]. Thus, in order to break
through a proficiency barrier, children need to engage in
practice and skill-specific experiences consistently through-
out childhood in a positive, yet challenging learning environ-
ment [58–62].
4.2 Intervention Works Very Well When it Starts
During theEarly Years
Mobility strategies are learned and occur through context-
specific experiences and practice only, which is critical for
promoting the shift from stability to mobility movement
strategies [54, 63–65]. Requiring context-specific practice
to learn motor skills is contrary to the common standard of
practice suggesting 30–60min of daily free play (recess)
provides adequate experiences and opportunities for young
children to develop fundamental motor skills [66, 67]. How-
ever, we do not wish to minimize the importance of free
play as it provides children with the opportunity to explore
their environment, socialize with peers, and a myriad of
other important developmental attributes. Thus, we suggest
providing both structured and context-specific unstructured
opportunities for children to learn to move. Unfortunately,
results from emerging data shows that more children are at
risk for developmental delay or actually demonstrate delay
in many fundamental motor skills [3, 68–70]. When exposed
to developmentally-appropriate instruction context-specific
physical activities, young children can continually advance
their motor skills with a dose of as little as six hours across
six weeks [54, 64, 71]. Thus, from a constraints perspec-
tive, providing continued and sequential mobility-specific
instruction for a variety of skills and adequate supplemental
experiences in the early years will promote the advancement
of movement skills so children have a better chance of break-
ing through the proficiency barrier.
Specifically for locomotor skills, instruction and experi-
ences that target the exploitation of neuromuscular mecha-
nisms (i.e., stretch–shortening cycle) that promote the rapid
transition from eccentric to concentric contractions in the
lower extremity kinetic chain (i.e., plyometric movements)
will promote COM translation in both horizontal and verti-
cal dimensions of movement (i.e., flight phase and increased
speed of COM translations). Promoting instruction and envi-
ronmental design that emphasizes speed of movement (e.g.,
faster, quicker) and/or larger excursions of the COM in vari-
ous locomotor activities (e.g., bigger, higher) as opposed to
focusing on instruction that only emphasizes positioning
and movements that attempt to mimic what advanced level
coordination patterns “look like” (e.g., body segment posi-
tional instruction that attempts to specify opposition in both
the lower and upper extremities) promotes moving beyond
stability and maintaining balance to moving the entire body
in a way that facilitates an unstable new coordination pat-
tern. This enhanced strategy for instruction has been noted
in developmental literature to promote advanced skill levels
(e.g., promote increased force or effort) [48, 72] as well as
progressions of locomotor movement drills (i.e., plyomet-
rics) in sport performance-based training [73]. The empha-
sis on effort-based movement promotion also is embedded
within the context of many games and activities (e.g., races
or timed performance) and can be easily promoted via
appropriate environmental design of tasks.
Attempts to perform at a more advanced level with an
emphasis on higher effort trigger the exploitation of multiple
biomechanical and neuromuscular function principles. First,
linear (COM) and rotational energy (across joints) is gener-
ated and transferred through multiple body segments via a
closed kinetic chain mechanism across multiple segments
with increased force production [48]. Increased force pro-
duction is promoted via the exploitation of elastic muscle/
connective tissue contributions within the context of rapid
eccentric/concentric muscle actions where energy is initially
generated during preparatory eccentric movements (e.g.,
preparatory jumping movements of arms and the lowering
of the COM) and is transferred via subsequent concentric
movements. Highly skilled individuals, as compared to
less skilled individuals, effectively incorporate more seg-
ments into their movement patterns and utilize kinetic chain

Operationalizing Seefeldt’s Proficiency Barrier
principles more effectively to maximize energy transfer [46,
47, 74] and increase performance.
In addition, promoting this global transition to more
explosive faster movements may trigger, without explicit
instruction, perturbations in upper extremity actions that
also serve to destabilize the “stability” coordination dynam-
ics between the upper and lower extremities and promote
more advanced “mobility” coordination strategies between
the upper and lower extremities (i.e., beginning opposition
between the upper and lower extremity movements). While
this strategy may initially promote a loss of balance and sta-
bility in bipedal posture as well as the coordination between
the upper and lower extremities (e.g., loss of balance and
decreased performance), this perturbation in system dynam-
ics is necessary to initiate the transition to more advanced
mobility strategies. This strategy to promote a more
advanced coordination pattern, and ultimately increased
performance, is akin to identifying and exploiting a control
parameter (i.e., terminology used in motor control language)
that functions to destabilize existing coordination patterns
(i.e., the current order parameter) and foster the emergence
of a new pattern. It is important to understand and effectively
translate these principles into instruction across multiple
developmental periods (i.e., across childhood and adoles-
cence), but with developmentally appropriate instructional
and training strategies. For example, instructional informa-
tion and intervention settings will look quite different in
early childhood practices, with fundamental motor skill ter-
minology (i.e., step with opposition, move to the beat) being
used, as opposed to adolescence where long-term athletic
development (LTAD) language (e.g., dynamic stretching
[stretch while moving], plyometrics [explosive, fast, jump-
ing movements]) may be more appropriate in a sport setting.
Overall, the skills promoted in early childhood and advanced
training for sport are similar (i.e., various forms of jumping,
hopping, skipping, etc.) with a similar intent of promoting
enhanced mobility strategies (i.e., advanced skill patterns
and technique) and ultimately, performance.
5 A Shift fromaProciency Barrier
toBarriers Towards Prociency: Future
Directions andRecommendations
What underlying changes occur as a function of practice?
Seefeldt [18] suggested a “period of readiness” or sensitiv-
ity to practice in children between the ages of 4 and 7years
old. Theoretically, gross motor intervention should be more
effective during the early years than during middle-to-late
childhood. However, what is occurring, neurologically, that
supports ease of learning during early years as opposed to
greater challenges with initial skill learning/skill improve-
ment in later years? We recognize the extent to which
degrees of neuroplasticity support ease and depth of skill
learning is relatively unknown. Thus, we recommend future
investigations explore the role that neuroplasticity plays in
motor skill development and also the differential effects of
gross motor intervention across childhood and adolescence.
Future examinations should build upon the preliminary
studies that provide evidence to support that children with
motor skill levels below the proficiency barrier are indeed
less likely to be physically active [22], physically fit [15, 21]
and maintain a healthy weight [14, 15]. As more children are
demonstrating low levels of motor competence [3] that is
linked to mobility strategies of movement and developmen-
tal delay, future intervention studies should also examine if
there is a specific dose of intervention/practice needed to
overcome potential delay and advance beyond a potential
proficiency barrier. Thus, future research should examine the
mediational role of growth and maturation in overcoming a
proficiency barrier [75].
Rudimentary or intermediate motor skill levels which fall
below the proficiency barrier may show differential effects
for children who mature later than those with normal or early
maturation. Finally, future studies should continue to test the
potential existence of a proficiency barrier through multiple
measures and across time, both by cohort and longitudinal
observational studies. Recently, Getchell etal. [76] offered
suggestions for conducting rigorous motor development
studies. Among those suggestions were cross-sequential
designs where researchers can assess initial age, longitudi-
nal effects, and do so across multiple age-bands. Within a
cross-sequential design, we suggest using dependent meas-
ures such as meeting physical activity recommendations,
frequency of sport, type of sport (e.g., recreational vs com-
petitive), and game engagement, to test how stability versus
mobility profiles predict the likelihood of engagement and/
or meeting recommendations.
Future research also should test the proficiency barrier
hypotheses across a wide-variety of age, sex, gender, eth-
nicity, race, location, socioeconomic status, disability-type,
and body weight status to capture the greatest amount of
generalizability. Overall, providing a framework to explore
testing of the proficiency barrier hypothesis is important to
effectively measure the potential impact that a proficiency
barrier may have on multiple public health issues and other
developmental outcomes.
6 Implications forPractice andMotor
Learning
Improving skill development through practice during the
early years will promote a stronger foundation of skill upon
which children can continue positive developmental trajec-
tories of skill learning. Conversely, those who do not have

A.Brian et al.
these early experiences are not necessarily barred from
acquiring motor skills. However, individuals without early
experiences with fundamental motor skills may require
much more practice than a child with early experiences in
order to achieve an advanced skill level. In addition, with-
out early, developmentally-appropriate experiences, children
would be limited in their ability to explore alternative, con-
text-specific movement solutions that enhance mobility in
more complex (e.g., sport related) movement settings. As a
result, they maintain their stability strategy as the safest and
most secure manner to perform the desired skill, ultimately
limiting their ability to successfully participate in activities
that require advanced skill performance.
The requirement for significantly more practice to transfer
from rudimentary skill level to advanced motor skill learning
amplifies the notion that a proficiency barrier is difficult to
overcome. Notably, the increasing amount of practice nec-
essary for advanced motor skill learning needs to occur, as
currently there is little emphasis on structured motor experi-
ences during the early years, reduced time in free play, and
also decreasing number of practice opportunities for novice
performers since many sport-related programs become more
competitive with advanced age groups. In essence, if a child
lacks the skills to successfully participate in games, sports
and recreational activities in the early years, opportunities
to learn skills dwindle across time, making it more difficult
to overcome this barrier to lifelong participation.
7 Conclusion
The impasse that we have reached in the obesity epidemic,
as well as declines in gross motor development and fitness,
and surging rates of sedentary behaviors requires that we
must look for new ways to understand what drives the prob-
lem. We can no longer suggest simplistic solutions (con-
tinuing to ignore the role of motor development) for this
complex issue (e.g., increase physical activity to decrease
adipose tissue), particularly in light of the fact that global
rates of obesity continue to grow. Motor skill development
will play a critical role in both the quality and quantity of
physical activity individuals engage in across the lifespan.
To this end, we posit that a proficiency barrier is an impor-
tant consideration for addressing the development of physi-
cal activity behaviors and that children must transcend this
barrier in multiple skills in order to move in more energeti-
cally demanding patterns [77, 78] inherent in a variety of
activities across childhood and adolescence.
In conclusion, we reconceptualized and expanded upon
Seefeldt’s (1980) hypothetical proficiency barrier model by
situating the divide between stability and mobility coordi-
nation patterns that relate not only to skill development and
performance, but also to future health-related behaviors.
The early years are the ideal time for children to learn and
develop a wide-variety of fundamental motor skills through
structured and unstructured, developmentally-appropriate
experiences in safe and positive environments. If children
are successful during the early years, they will be more
likely to learn advanced level, mobility-enhancing levels
in a variety of motor skills. Motor skills are not birthday
presents with acquisition occurring purely as the result of
maturation [79]. Rather, in order to overcome a hypothe-
sized proficiency barrier, children need to practice skill in a
developmentally appropriate and mobility promoting envi-
ronment, which should be specifically designed to allow for
individual levels of development. The mechanism by which
children transition from stability to mobility strategies is
through motor skill learning and practice. We emphasize that
this transition does not occur naturally, but requires skill-
specific practice and experiences. Without adequate prac-
tice, secular decline in motor skill competence is imminent
[3] and may lead to further secular decline in PA, fitness
and increasing obesity levels. An appropriate foundation of
coordination and control that facilitates successful participa-
tion in a variety of health-enhancing physical activities also
serves to augment aspects of self-concept (e.g., perceived
competence, self-efficacy and self-worth) that also support
future development of positive trajectories of overall health
and well-being.
Compliance with Ethical Standards
Conflict of interest Ali Brian, Nancy Getchell, Larissa True, An De
Meester and David Stodden declare that they have no conflicts of inter-
est relevant to the content of this review.
Funding No sources of funding were used to assist in the preparation
of this article.
Ethics approval Not applicable.
Consent to participate Not applicable.
Consent for publication All authors provided consent for publication.
Availability of data and materials Not applicable.
Code availability Not applicable.
Author contributions AB, NG, and DS wrote the first draft of the man-
uscript. AB, NG, DS, LT, and AD revised the original manuscript. All
authors read and approved the final manuscript.
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