Effects of swimming intervention on motor competence and dynamic balance in children at risk for developmental coordination disorder: a pre-post intervention study

Developmental Coordination Disorder (DCD) affects approximately 5-6% of school-aged children, presenting significant motor skill impairments that can persist into adulthood if not addressed. Aquatic-based swimming programs have emerged as a promising avenue for supporting motor development in children facing neurodevelopmental motor challenges. However, robust evidence specifically evaluating structured swimming interventions for DCD-related motor impairments has been limited until now. A recent study, conducted by researchers in Chengdu, China, aimed to fill this gap by investigating the pre-post changes in motor competence and dynamic balance among children identified as being at risk for DCD, following a structured 10-week breaststroke swimming program.

The research, published in Frontiers in Psychology, involved 14 children (9 boys, 5 girls) with an average age of 8.25 years. These participants, identified through a school-based screening process as being at risk for DCD, underwent a comprehensive 10-week intervention. The program comprised 20 sessions, each lasting 60 minutes, conducted twice weekly. Motor competence was assessed using the Movement Assessment Battery for Children-Second Edition (MABC-2), while dynamic balance was evaluated using the Y-Balance Test Lower Quarter (YBT-LQ). Both assessments were administered before the intervention began and immediately after its conclusion.

Key findings from the study revealed statistically significant positive changes in motor competence. The MABC-2 Total Test Score showed a substantial increase from pre- to post-intervention, indicating an overall improvement in motor skills. Notably, the Aiming and Catching subdomain exhibited particularly strong gains, suggesting enhanced hand-eye coordination and ball-handling abilities. While the Balance subdomain of the MABC-2 did not reach statistical significance, the improvements observed in overall motor competence and specific skill areas offer preliminary evidence of the swimming program’s potential benefits.

In terms of dynamic balance, the Y-Balance Test Lower Quarter results demonstrated improvements across several reach directions. After accounting for multiple comparisons, four out of the six reach directions showed statistically significant gains, with medium-to-large effect sizes. These improvements were observed in both the left and right anterior and posteromedial reach directions, suggesting enhanced postural control and stability in these movement planes.

The study reported a remarkable 100% retention rate among participants, with no adverse events recorded. This high level of engagement and safety underscores the feasibility and acceptability of the structured swimming intervention in this cohort. The researchers noted that the program’s design, including its progressive complexity, standardized coaching cues, and consistent pool conditions, likely contributed to its successful implementation.

Implications of these findings suggest that structured aquatic programs, such as the breaststroke swimming intervention studied, may offer a valuable complementary approach for supporting motor development in children at risk for DCD. The water’s buoyancy and resistance can create a unique environment that may facilitate repeated practice of motor skills with reduced physical demand and enhanced sensory feedback. However, the study’s authors emphasize that these results are preliminary and derived from a single-group design. Further controlled trials are needed to establish causal efficacy and to determine the long-term durability of these observed improvements.

Background: Understanding Developmental Coordination Disorder

Developmental Coordination Disorder (DCD) is a neurodevelopmental condition that affects a significant portion of the pediatric population, impacting their ability to perform everyday motor tasks. Children with DCD often struggle with activities such as writing, playing sports, dressing, and navigating their environment. This can lead to frustration, low self-esteem, reduced physical activity, and social isolation. The condition is not attributed to intellectual disability, neurological impairment, or other developmental disorders, but rather to difficulties in the planning and execution of movements.

The prevalence of DCD, estimated at 5-6% of school-aged children, highlights the widespread need for effective interventions. Without appropriate support, these motor challenges can persist into adolescence and adulthood, continuing to affect daily functioning and life choices. Identifying and implementing accessible and engaging interventions is therefore a critical public health and educational priority.

The Aquatic Environment as a Therapeutic Modality

The water’s unique physical properties have long been recognized for their therapeutic benefits. Buoyancy reduces the effects of gravity, lessening the impact on joints and making movement less taxing. This can be particularly advantageous for individuals with motor impairments, allowing for a greater range of motion and reduced risk of falls. Water resistance, on the other hand, provides a consistent and graded challenge to muscles, promoting strength and endurance. Furthermore, the hydrostatic pressure of water offers continuous sensory input, which can enhance proprioception and body awareness.

For children with DCD, these characteristics can create an optimal environment for motor learning. The reduced fear of falling, coupled with the increased sensory feedback, may allow children to practice complex movements more effectively and with greater confidence. Swimming, as a whole-body activity that inherently involves coordination of limbs, breathing, and balance, is a natural fit for leveraging these aquatic benefits.

Study Design and Methodology

The study, conducted in Chengdu, China, from September 2025 to January 2026, employed a single-group pre-post intervention design. This approach allowed researchers to observe changes within the same group of participants before and after the intervention. While this design is valuable for exploring potential effects and feasibility, it does not allow for definitive conclusions about causality due to the absence of a control group.

Participant Recruitment and Screening:
A multi-stage screening process was implemented to identify children at risk for DCD. Initially, 234 Grade 1 to Grade 3 students from a primary school in Chengdu were assessed. Classroom teachers identified students exhibiting persistent motor difficulties in daily school activities. This pragmatic approach helped narrow down the pool of potential participants. Out of this group, 90 candidates underwent formal assessment using the MABC-2. Children scoring below the 16th percentile on the MABC-2, and who fell within Age Band 2 (7-10 years), were classified as being at risk for DCD and invited to participate. This yielded a final cohort of 14 children (9 boys, 5 girls) with a mean age of 8.25 years. The proportion of identified at-risk children (5.98%) aligned with the known prevalence of DCD, lending credibility to the screening outcome.

The 10-Week Breaststroke Swimming Program:
The intervention was meticulously structured over 10 weeks, involving 20 sessions of 60 minutes each, held twice weekly. An experienced coaching team delivered a standardized curriculum designed to progressively increase complexity and intensity. The program was broken down into five developmental phases:

• Phase 1 (Week 1): Aquatic Adaptation: Focused on water comfort, breathing control, and voluntary facial submersion.
• Phase 2 (Weeks 2-3): Lower Limb Mechanics: Concentrated on the fundamental kicking techniques for breaststroke.
• Phase 3 (Weeks 4-5): Leg-Respiration Integration: Emphasized coordinating leg movements with breathing patterns.
• Phase 4 (Weeks 6-8): Upper Limb Technique: Introduced arm stroke mechanics and synchronization with breathing.
• Phase 5 (Weeks 9-10): Full Stroke Synthesis: Integrated all components into complete breaststroke execution, culminating in a performance assessment.

This structured approach, detailed in a manualized format, aimed to ensure reproducibility and intervention fidelity. The chosen dose of 20 sessions was considered sufficient for motor learning while remaining feasible for families.

Outcome Measures:
The study utilized two established assessment tools to measure changes:

• Movement Assessment Battery for Children-Second Edition (MABC-2): This test assesses motor performance across three domains: Manual Dexterity, Aiming and Catching, and Balance. It is widely used to identify motor impairments in children aged 3-16 years. For this study, Age Band 2 (7-10 years) was administered. Scores are converted to standard scores and percentile ranks, with lower scores indicating greater motor impairment. The MABC-2 has demonstrated good reliability and validity.

• Y-Balance Test Lower Quarter (YBT-LQ): This test evaluates dynamic balance by requiring participants to stand on one leg and reach as far as possible with the other leg in three directions: anterior, posteromedial, and posterolateral. Reach distances are normalized to leg length. The YBT-LQ is known for its high test-retest and inter-rater reliability. It provides insights into an individual’s ability to maintain balance during functional movements.

Statistical Analysis:
Statistical analyses were conducted using R software. Paired-samples t-tests were used for normally distributed data, and Wilcoxon signed-rank tests were applied for non-normally distributed data to compare pre- and post-intervention scores. Effect sizes were calculated using Cohen’s dz for paired samples and r for Wilcoxon tests, with established benchmarks for interpretation (small, medium, large). To address the issue of multiple comparisons, the Holm-Bonferroni procedure was applied to the MABC-2 and YBT-LQ outcomes separately, ensuring control of the family-wise error rate.

Detailed Results: Unpacking the Improvements

The detailed results of the study offer a nuanced view of the intervention’s impact:

Motor Competence (MABC-2):

• Total Test Score: The median MABC-2 Total Test Score increased significantly from 9 to 16 post-intervention. This represents a median change of 5.50 points, with a large effect size (r=0.72), and remained statistically significant after adjustment for multiple comparisons (adjusted p=0.021). This indicates a general improvement in overall motor skills.
• Aiming and Catching: This subdomain saw the most pronounced improvement, with the median score rising from 25 to 50. The median change of 25.00 points, accompanied by a large effect size (r=0.78), was statistically significant even after adjustment (adjusted p=0.014). This suggests that the swimming program positively impacted skills related to hand-eye coordination and projectile manipulation.
• Manual Dexterity: While there was a numerical increase in the median score from 5 to 7 (median change 0.5), this did not reach statistical significance after adjustment for multiple comparisons (adjusted p=0.100), although it approached significance unadjusted (p=0.050) with a moderate effect size (r=0.52).
• Balance: The MABC-2 Balance subdomain showed a median score increase from 25 to 37 (median change 0.00), but this change was not statistically significant (adjusted p=0.100) with a moderate effect size (r=0.45). The high variability in this domain was noted, suggesting individual differences in how children responded to the balance-related aspects of the swimming intervention.

Dynamic Balance (Y-Balance Test Lower Quarter):

• Left Leg:
  • Anterior Reach: Improved significantly, with a mean change of 3.26 cm (95% CI: 0.80-5.71), a large effect size (dz=0.77), and remained significant after adjustment (adjusted p=0.045).
  • Posteromedial Reach: Showed a significant increase of 2.16 cm (95% CI: 0.59-3.72), a large effect size (dz=0.79), and was statistically significant after adjustment (adjusted p=0.045).
  • Posterolateral Reach: Demonstrated a numerical improvement of 1.60 cm (95% CI: 0.19-3.01) with a moderate effect size (dz=0.66), but did not remain statistically significant after adjustment (adjusted p=0.058).
• Right Leg:
  • Anterior Reach: Exhibited a substantial improvement of 4.18 cm (95% CI: 1.31-7.05), a large effect size (dz=0.84), and was statistically significant after adjustment (adjusted p=0.045).
  • Posteromedial Reach: Increased by 3.30 cm (95% CI: 1.04-5.55), a large effect size (dz=0.85), and remained statistically significant after adjustment (adjusted p=0.045).
  • Posterolateral Reach: Showed a numerical improvement of 2.17 cm (95% CI: -0.09-4.43) with a moderate effect size (dz=0.55), but did not reach statistical significance after adjustment (adjusted p=0.059).

The consistent improvements in anterior and posteromedial reach directions across both legs suggest a targeted benefit of the swimming intervention on certain aspects of dynamic balance.

Feasibility and Practical Considerations

The 100% retention rate and absence of adverse events are critical indicators of the intervention’s feasibility. This suggests that the structured, twice-weekly swimming program was well-tolerated and engaging for the children and their families within the study’s context. The researchers highlighted that the program was delivered in a temperature-controlled pool by trained coaches following a standardized manual. This level of structure and support is crucial for replicability and success.

The findings, while promising, come with caveats. The study was conducted in a specific urban setting in China, and the participating school may draw from a diverse community. However, without detailed demographic data on cultural or ethnic backgrounds, it is difficult to generalize these findings to broader populations. The practical implications for schools or communities lacking dedicated aquatic facilities or trained personnel are also important to consider. For such settings, alternative land-based or lower-resource interventions might be more appropriate.

The observed median change in the MABC-2 Total Test Score (5.50 points) is noteworthy as it falls near the upper limit of the published minimal detectable change (MDC) range for the MABC-2. This suggests that the improvements observed may be clinically meaningful and potentially surpass measurement error. However, the absence of a universally defined minimal clinically important difference (MCID) for MABC-2 interventions means this interpretation should remain cautious.

Limitations and Future Directions

The researchers acknowledge several limitations that temper the conclusions drawn from this study:

• Single-Group Design: The absence of a control group means that observed improvements cannot be definitively attributed to the swimming intervention alone. Maturation, practice effects from repeated testing, and other environmental factors could have contributed to the changes.
• Sample Size and Selection: The small sample size of 14 children, recruited from a single school, limits the generalizability of the findings. The initial teacher-based screening might have preferentially identified children with more pronounced motor difficulties, potentially introducing selection bias.
• Diagnostic Specificity: Participants were classified as "at risk for DCD" based on MABC-2 scores rather than a formal DSM-5 diagnostic process. Functional impairment in daily activities and co-occurring neurodevelopmental conditions were not formally assessed, which may limit direct comparison to clinically diagnosed DCD populations.
• Exploratory Nature of Secondary Outcomes: While multiplicity adjustments were made, several subdomain and directional analyses remained exploratory. The study was not powered specifically for these secondary outcomes.
• Short Follow-Up Period: The study only assessed immediate post-intervention changes. The long-term durability of these improvements remains unknown.

To address these limitations, future research should incorporate randomized controlled trials with appropriate control groups, larger and more diverse participant samples, and extended follow-up periods. The inclusion of functional outcome measures beyond standardized motor assessments is also crucial to understand the real-world impact of interventions. Furthermore, research investigating predictors of treatment response could help personalize interventions for children with DCD.

Conclusion: A Promising Step Forward

This study provides preliminary, feasibility-informed evidence that a structured 10-week breaststroke swimming program can lead to positive pre-post changes in motor competence and dynamic balance in children identified as being at risk for Developmental Coordination Disorder. The most significant improvements were observed in overall motor skills (MABC-2 Total Test Score), aiming and catching abilities, and several aspects of dynamic balance assessed by the Y-Balance Test Lower Quarter. The high retention rate and absence of adverse events underscore the program’s feasibility and acceptability.

While these findings are encouraging, they should be interpreted cautiously due to the study’s single-group design and other methodological limitations. The results strongly advocate for further controlled investigations to confirm the efficacy and long-term benefits of structured swimming interventions for children with DCD. Such research will be vital in guiding the development of evidence-based recommendations for incorporating aquatic programs into broader intervention strategies for this population.