Developmental coordination disorder (DCD) is characterized by marked impairments in the development of motor coordination, which affects the performance of manipulation, locomotion and balance skills, in a general or specific way. It significantly affects a child’s participation in activities of daily living (ADL) and school (ADS) (Smits-Engelsman et al., 2025; Tamplain et al., 2024; Farhat et al., 2024; Landgren et al., 2021; Magalhães et al., 2011; Miller et al., 2021; Sugden et al., 2008; Kirby and Sugden, 2007; Zoia et al., 2006; Sugden et al., 2006). It is a complex condition of as yet unknown cause, whose diagnosis is based on symptoms that are recurrent and independent of culture, race and socioeconomic status (Gao et al., 2024; Blank et al., 2019; Smits-Engeslman et al., 2012; Lingam et al., 2009; Kadesjo and Gillberg, 1999).

Its incidence in the school-age child population is 6% (American Psychiatric Association, 2013), which already makes it one of the most frequent disorders in childhood (Zwicker et al., 2012; Wann, 2007), and the majority of children identified with DCD continue to present motor disorders in adolescence and adulthood (McQuillan et al., 2021; Poulsen et al., 2008; Sugden et al., 2008; Zoia et al., 2006; Sugden et al., 2006; Cantell et al., 2003).

Developmental coordination disorder has been a subject of interest to researchers who aim to understand its cause, improve diagnosis and investigate the effects of intervention programs (Gao et al., 2024; Ayyash and Preece, 2003). Studies examining the effects of intervention programs on DCD have looked at a variety of aspects, such as the influence of different developmental disorders (comorbidities) on the results of the programs (Watemberg et al., 2007); the response of DCD subgroups to interventions (Green et al., 2008); comparison between individual application and group application (Hung and Pang, 2010); the effects of graded exergames on fitness performance (Smits-Engelsman et al., 2021), and comparison between teacher-guided and parent-guided programs (Sugden and Chambers, 2003; Rintala et al., 1998).

Moreover, examining the efficacy of different perspectives of motor interventions for children, Smits-Engeslman et al. (2012) concluded that interventions approaches from a task-oriented perspective yields stronger effects than process-oriented approaches and Ghorbanzadeth et al. (2024) that the combination of the teaching games for understanding (TGFU) and sport education (SE) teaching method is the best method for improving the motor proficiency of DCD children compared to teaching games for understanding TGFU, SE, and linear methods.

In general, the results of these studies have shown that intervention programs have the potential to improve the motor performance of children with DCD, reducing primary impairments (e.g., disorders with motor skills related to manipulation, stabilization, and locomotion) and possibly secondary impairments (e.g., negative consequences on self-esteem, self-concept, perception of competence, and social relationship). However, while in Polatajko et al. (1995) and Eliasson et al. (2003) the effects on short-term motor performance were not resistant to time, in two other studies (Sugden and Chambers, 2003, 2006) they remained in the post intervention long term tests. In this sense the results concerning the maintenance of these effects over time are still controversial.

Nonetheless, with the exception of one exploratory study, the studies that have investigated the effects of intervention programs on the DCD population have only used the terrestrial environment (clinics, school gyms and the home) and little is known about the maintenance of these effects on motor performance after the intervention has ended, i.e., over time. On the other hand, the aquatic environment has been the most used environment in studies that have investigated the effects of intervention programs for people with atypical development (cerebral palsy, autistic and visually impaired) and its effects have been studied frequently (Ogonowska-Slodownik et al., 2024; Zhao et al., 2024; Vodakova et al., 2022; Dimitrijevic et al., 2012; Getz et al., 2012; Jorgic et al., 2012; Pan, 2011, 2010; Fragala-Pinkham et al., 2008).

A study conducted by Jorgic et al. (2012), for example, evaluated seven children with cerebral palsy, aged between 8 and 10 years, who only underwent aquatic intervention over a period of 6 weeks. The results indicated significant improvements in the performance of walking, running and jumping skills. Another study just investigating the effects of aquatic intervention on the motor performance of children with cerebral palsy was carried out by Dimitrijevic et al. (2012). The participants were 27 children aged between 5 and 14 years old, divided into two groups – control and experimental. The intervention was applied for 6 weeks. The results showed that the motor performance of the experimental group, i.e., the one that underwent aquatic intervention, was superior to that of the control group. However, the effects obtained as a result of the intervention were not maintained over time.

The researchers argued that the effects of aquatic intervention are enhanced by the specific properties of this environment. The viscosity combined with the hydrostatic pressure favors muscle strengthening without damaging the tissues or causing too much tension on specific parts of the body. They also state that the hydrostatic pressure exerted on blood vessels causes an increase in respiratory and circulatory activity and an increase in muscle tone, making motor performance more efficient (Getz et al., 2012; Fragala-Pinkham et al., 2008). Also noteworthy is the important role of buoyancy in supporting the joints and stabilizing the body. The more a body is immersed, the greater the action of buoyancy and, consequently, the lower the overload exerted by the action of gravity (Getz et al., 2006, 2012; Pan, 2011).

By analogy, we understand that the aquatic environment also has the potential to enhance the effects of interventions on the motor performance of children with DCD. However, we found only one study that investigated the effects of aquatic intervention on this population. Hillier et al. (2010) selected 12 children with DCD between the ages of 5 and 8 years and divided them into two groups – control (non-intervention) and experimental. Intervention was applied for 6 weeks, with one session per week, and addressed specific tasks of static balance, ball skills and walking/running.

No significant differences were found from pre-test to post-test. These results indicate that the aquatic intervention program had no significant effects on children with DCD. However, these results should be interpreted with caution as the intragroup analysis revealed that the experimental group decreased by 20% (3.9 points) their total score on the MABC test, indicating that motor performance improved after the intervention, while the control group increased by 14% (2.6 points), indicating impairments in motor performance. According to the researchers, although no significant differences were observed between the groups, those results lend clinical significance to the aquatic intervention program for the motor performance of children with DCD.

It is also important to consider the reduced number of weekly sessions (1) and the short period of application of the intervention (6 weeks), as intervention studies carried out in the terrestrial environment indicate that the weekly frequency combined with longer periods of application of the program are important variables (Polatajko et al., 1995; Eliasson et al., 2003; Sugden and Chambers, 2003).

Considering the information above, we would like to emphasize that knowledge about the effects of aquatic intervention on children with DCD, as well as about the maintenance of these effects over time, is still scarce. As for land-based intervention, all of the studies show positive effects on motor performance. However, the results concerning the maintenance of these effects over time are still controversial. We therefore believe that there is a need to advance our knowledge of this subject, for which we have set ourselves the following research questions: (1) Are there effects of aquatic and land-based interventions on the motor performance of children with DCD? (2) Do these effects persist over time? and (3) Do the effects of aquatic and land-based interventions bring motor performance values closer together between children with DCD and those with typical development? Hereto, the following objectives were pursued in this study: (1) to test whether the effects of aquatic and land-based interventions influence the motor performance of children with DCD; (2) to check whether these effects persist over time; and (3) to investigate whether the effects of aquatic and land-based interventions are capable of narrowing the gap in motor performance between children with DCD and those with typical development.

The research questions posed were: (1) Are there effects of aquatic and land-based interventions on the motor performance of children with DCD? (2) Do these effects persist over time? and (3) Do the effects of aquatic and land-based interventions bring motor performance values closer together between children with DCD and those with typical development?

With regard to the first question, the results allowed us to answer in the affirmative, i.e., that the terrestrial and aquatic interventions had a positive influence on the motor performance of children with DCD.

Results involving the motor performance scores do not indicate a significant difference between the T-DCD and A-DCD groups but revealed between the T-DCD and C-DCD groups. T-DCD group showed significant results immediately after the end of the intervention. As the three DCD groups (A-DCD, T-DCD and C-DCD) started from the same performance level, it can be inferred that the difference found between the T-DCD and C-DCD groups was due to the land-based intervention. For the time factor, differences were found between the pre-test and the other times, i.e., post-test, 3 months-post-test and 6 months-post-test. These effects were of great magnitude, suggesting that there was clinical significance for the T-DCD group over time. This result indicates that there was an improvement in motor performance over time, with no distinction between groups.

Taken together, these results reinforce the evidence on the effectiveness of land-based interventions for children with DCD (Green et al., 2008; Niemeijer et al., 2007; Watemberg et al., 2007; Sugden and Chambers, 2003, 2006; Schoemaker et al., 2003; Pless et al., 2000; Kaplan et al., 1993).

On the other hand, the analysis involving the motor performance scores revealed no significant difference between the A-DCD and C-DCD groups. The beneficial effects of the aquatic intervention found for the A-DCD group were not enough to differentiate it statistically from the control group (C-DCD). We suggest that considering the intervention environment, it is possible that the improvement in motor performance in skills performed in the aquatic environment is not completely transferred to the performance of equivalent motor skills in the terrestrial environment, requiring a longer time for this improvement to take effect, as the results here have shown. Transfer, for example, is a subject of research in the area of Motor Learning (Schmidt and Young, 1987; Holding, 1976).

As mentioned, the results of the present study showed that no differences were detected between the T-DCD and A-DCD groups. However, the T-DCD group showed significant results immediately after the end of the intervention and when the magnitude of the effect was analyzed, it showed effects ranging from large to small over the course of the evaluations compared to the A-DCD group. We believe that this result reinforces the argument that the children in the A-DCD group found it difficult to transfer motor skills developed in the aquatic environment to equivalent ones performed on land.

The results of this study are in line with those of Hillier et al. (2010), who also found no significant difference between the experimental and control groups after aquatic intervention, although they did observe an increase in the motor performance score in 50% of the children in the experimental group. In the same way, in our study, with the groups starting from the same level, as evidenced by the magnitude of the effect sizes found, the children in the A-DCD group showed greater improvements in motor performance over time than those in the C-DCD group. This confirms the clinical significance of the aquatic intervention mentioned by Hillier et al. (2010).

Beyond that, maybe because the number of sessions was higher, our results go further than those found by Hillier et al. (2010). In the present study the A-DCD group showed significant intra-group effects in motor performance after the intervention, as well as in the 3- and 6-months post-tests.

Summarizing, this study showed that both land-based and aquatic interventions were effective in improving the motor performance of children with DCD. Moreover, although the results do not indicate a significant difference between the T-DCD and A-DCD groups, we observed a slight superiority of the land-based intervention over the water-based one.

The second question arises because we assume, however, that the effectiveness of an intervention is only confirmed if the effects are maintained over time. This was in fact observed in the present study because differences were found between the pre-test and the other times, i.e., post-test, 3 months-post-test and 6 months-post-test. These results indicate that the effects were maintained over the 6 months following the intervention for both experimental DCD groups.

Studies looking at the maintenance of the effects of interventions are rare (Smits-Engeslman et al., 2012). We believe that our study makes it possible to advance knowledge regarding land-based interventions, since it was found that the effects were maintained in evaluations after the end of the intervention. The design of this study, specifically with regard to the length (4.5 months or 18 weeks) and with three sessions a week complies with the recommendations in the literature, specifically involving the planning of intervention programs (Sugden et al., 2006; Pless and Carlsson, 2000). By comparison, the interventions in the studies by Polatajko et al. (1995) and Eliasson et al. (2003) comprised a reduced number of weeks (5 and 9, and 8, respectively), which we believe may have influenced the failure to maintain the effects achieved with these interventions.

Specifically, concerning aquatic intervention and children with DCD, we found no studies focusing on the maintenance of effects after intervention. In this respect, the results of the present study, showing the effectiveness of aquatic intervention for individuals with DCD (intragroup significant differences), also represent an advance in this field of research.

In relation to the third question of the study, with regard to the Z score, no differences were detected between the T-DCD and A-DCD groups. We therefore consider that the aquatic intervention showed similar benefits to the land-based intervention in terms of its tendency toward the reference for children with typical development.

In turn, the analysis of the Z score showed that the T-DCD group differed from the C-DCD group in terms of its approximation to the reference for children with typical development 6 months after stopping the intervention. It should be noted that these groups started from the same performance level, i.e., before the intervention they both differed equally from the benchmark for children with typical development. The results show that the T-DCD group was closer to the reference. These effects were of great magnitude, attesting to the clinical significance of the terrestrial intervention.

The analysis of the Z score showed that also the A-DCD and C-DCD groups differed in terms of how close they were to the reference for children with typical development 6 months after the intervention. This was not the case with the C-DCD group. It should be noted that these groups started from the same performance level. As with T-DCD, the results show that the A-DCD group was closer to the reference. However, only the A-DCD group showed a trajectory toward the reference group which began shortly after the intervention and became similar to it after 6 months. These results strengthen claims about the potential of the aquatic environment to help children with motor disorders of different etiologies (Zhao et al., 2024; Ogonowska-Slodownik et al., 2024; Pan, 2011; Hillier et al., 2010; Fragala-Pinkham et al., 2008; Getz et al., 2006, 2007); by extension, they have also shown that children with DCD without access to intervention tend to experience maintenance or worsening of their motor disorder (Cantell et al., 1994; Geuze and Borger, 1993; Losse et al., 1991; Gillberg et al., 1989).

Taken together these results suggest that, in relation to the reference, in functional terms, in the same way as for T-DCD, the A-DCD group became distanced from the C-DCD group. In this sense, although the land-based intervention enabled performance similar to that of typically developing children more quickly, the results suggest that the T-DCD and A-DCD groups got similarly close to the typical reference, which indicates similarity in their effectiveness in bringing the motor performance of children with DCD closer to that of children with typical development.

The results presented here serve as a warning, as they reinforce that without intervention, the difference between the developmental trajectory of children with DCD in relation to that of typical children can continue throughout adolescence and into adulthood (Payne and Ward, 2019; Tal-Saban and Kirby, 2018; Tal-Saban et al., 2012, 2014; Missiúna et al., 2007; Taylor et al., 2007; Henderson and Henderson, 2002; Cantell et al., 2001, 2003), negatively interfering with their development and quality of life (Cavalcante-Neto et al., 2025; Khairati et al., 2024; Nobre et al., 2023; Draghi et al., 2021; Zwicker et al., 2018; Liberman et al., 2013; Tal-Saban et al., 2012; Wagner et al., 2012; Zwicker et al., 2012; Bejerot et al., 2011; Hill et al., 2011; Rivilis et al., 2011; Engel-Yeger and Kasis, 2010; Missiúna et al., 2007; Sigmundsson et al., 1998).

Finally, they reinforce the statement by Tal-Saban et al. (2012) that regardless of the severity of the motor disorder, children with DCD need help to bring their developmental trajectory closer to that of children considered to have typical development.

In short, aquatic and terrestrial interventions were similar in terms of their effectiveness for children with DCD, as both equally benefited motor performance. It seems, then, that the environment in which the intervention takes place is not the main factor influencing improvements in children with DCD. In this study, the aquatic and terrestrial interventions were equivalent in terms of duration – 4, 5 months/18 weeks/54 lessons. Following existing recommendations, the weekly frequency was three sessions for both interventions (Sugden and Chambers, 2003, 2006; Pless and Carlsson, 2000). In addition, the thematic content developed in the sessions was equivalent.

Considering these specificities, the results of this study allow us to state that the effectiveness of the aquatic intervention and the land-based intervention are equivalent in terms of the benefits related to the motor performance of children with DCD.

We conclude that both aquatic and land-based interventions have positive effects on the motor performance of children with DCD and that these effects are not only maintained over time, but also bring the motor performance of children with DCD closer to that of children with typical development. However, we would point out that the land-based intervention proved to be effective immediately after it ended, while the aquatic intervention took longer to prove its effectiveness. In short, motor intervention, regardless of the medium in which it takes place, aquatic or terrestrial, is effective in treating children with DCD.

Based on these results and conclusions, future studies should be carried out with the aim, for example, of investigating the effects of aquatic intervention in relation to the skills specific to each of the subsections of the motor battery of the MABC-2 test. It is possible that aquatic intervention, due to the properties of the environment, particularly favors stabilization skills, for example. Another question that calls for future research concerns the interactions between the subtype of DCD, the severity of the disorder and the environment (aquatic or land-based), with regard to the outcome of the intervention.